MARIA FRANCA BRIGATTI - personale UniMoRe

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MARIA FRANCA BRIGATTI

PROFESSORE FUORI RUOLO Esterno
Dipartimento di Scienze Chimiche e Geologiche - Sede Dipartimento di Scienze Chimiche e Geologiche

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Pubblicazioni

2022 - The significance of iron ooids from the middle Eocene of the Transylvanian Basin, Romania [Articolo su rivista]
Papazzoni, C. A.; Cavalazzi, B.; Brigatti, M. F.; Filipescu, S.; Foucher, F.; Medici, L.; Westall, F.; Ferretti, A.
abstract

The middle Eocene ironstone of the Transylvanian Basin, Romania, provides new insight into the genesis and paleoenvironmental significance of ferruginous ooids. An horizon at the base of the Ca ̆pus" Formation in north-western Romania, well known for the spectacular nummulite banks there exposed, documents a peculiar association of large foraminifera within a matrix dominated by millimetric Fe-ooids. These red- brownish Fe-ooids are well evident through the whitish colour of the carbonatic host matrix. An inte- grated analysis of the ooids, carried out by Environmental Scanning Electron Microscopy, Micro-X-ray Diffraction and Raman spectroscopy, allowed its detailed chemical and mineralogical characterization. Ooids are mostly composed of continuous concentric cortical layers of goethite interlayered by a few thin layers of phosphatic phases, whereas nuclei are made of ferruginous grains. No evidence of biological activity was detected in the cortex of the ooids to support a bio-mediated genesis. The occurrence of this ironstone testifies the existence of ferruginous bottom waters in the Eocene tropical/sub-tropical shallow-marine settings of the central Neotethyan Realm. The limited extension of the iron source area suggests that also local (e.g., not global) events could have been able to trigger iron ooidal deposition throughout the Phanerozoic.

2021 - A time- and cost-saving method to check the point-to-point distribution of soil improvers [Articolo su rivista]
Malferrari, D.; Laurora, A.; Brigatti, M. F.; Di Giuseppe, D.; Faccini, B.; Coltorti, M.
abstract

Background: In recent times, also in compliance with several sustainable agriculture rules, the use of soil conditioners, such as zeolites, progressively increased. Zeolites are minerals characterized by unique physical-chemical properties, which make them able to control the mobility of water, ammonium and other cations in soils. As zeolites do not exhaust their properties over time, it would be appropriate to check for their correct distribution in the amended soil. Aims: We present an efficient and inexpensive method to measure the point-to-point amount of zeolite spread in the soil through the analysis of a single (i.e., one peak) X-ray powder diffraction signal. Methods: The procedure requires the preparation of a calibration curve using known quantities of non-amended soil, zeolite and of an internal reference standard. The amount of zeolite is calculated by comparing the intensities of the selected signal in unknown sample with its analogue in the calibration curve. Results: The method returned a small underestimation (about 12 weight %) of the measured values compared to those expected which depend nearly exclusively on the valuation of the apparent density of the soil, whereas it is not affected by the type and number of phases present in the soil and in the amendant. Conclusions: The proposed method allows to check for the regular distribution of zeolite in soil, but we are confident that it could also be conveniently generalized to all the applications that require the quantitative determination of mono or polyphasic crystalline materials within a complex mixture like soil.

2021 - Molecular structure and ammonia gas adsorption capacity of a Cu(II)-1,10-phenanthroline complex intercalated in montmorillonite by DFT simulations [Articolo su rivista]
Sainz-Diaz, C. I.; Castellini, E.; Escamilla-Roa, E.; Bernini, F.; Malferrari, D.; Brigatti, M. F.; Borsari, M.
abstract

A hydrated complex of 1,10-phenanthroline with Cu2+ cation was intercalated in the interlayer space of montmorillonite. This intercalation occurs initially by through a cation exchange mechanism in which the charge of the complex cation compensates the excess of the negative charge of the interlayer, then, once the cation exchange capacity (CEC) value has been reached, by direct adsorption of the sulfate salt of this complex (i.e. the cation together with its sulfate counterion). This material has showed interesting entrapping properties of gaseous phases and a peculiar chemical reactivity. However, the complete characterization and explanation of the formation of these materials is difficult with only experimental techniques. Hence, we used computational methods at atomic level to know how are the molecular structure of these complexes and their adsorption capacity of ammonia inside the interlayer confined space of montmorillonite for a better understanding of the experimental behaviour. First Principles calculations were performed based on Density Functional Theory (DFT). The intercalation of the phenanthroline-Cu(II) complex inside the nanoconfined interlayer of montmorillonite is energetically favourable in the relative proportion observed experimentally, being a cation exchange process. The further adsorption of the sulfate salt of the phenanthroline-Cu complex is also energetically possible. The adsorption of ammonia molecules in these montmorillonite-phenanthroline-Cu complexes was also favourable according with experimental behaviour.

2021 - The Copper Chemical Garden as a Low Cost and Efficient Material for Breaking Down Air Pollution by Gaseous Ammonia [Articolo su rivista]
Castellini, Elena; Bernini, Fabrizio; Sebastianelli, Lorenzo; Bighi, Beatrice; Ignacio Sainz-Diaz, Claro; Mucci, Adele; Malferrari, Daniele; Ranieri, Antonio; Gorni, Giulio; Marini, Carlo; Brigatti, Maria Franca; Borsari, Marco
abstract

Chemical garden (CG) from copper(II) sulfate, nitrate and chloride (CG CuSO4, CG Cu(NO3)2, CG CuCl2) were grown and characterized from the structural and compositional point of view using scanning electron microscopy, X-ray powder diffraction, elemental analysis, thermogravimetric analyses coupled with mass spectrometry, and DR (Diffuse Reflectance) UV-Vis-Nir spectroscopy. The main crystalline phases, controlled by the anion of the starting salt, were brochantite and kobyashevite for CG CuSO4, gerhardtite, rouaite and anthonyite for CG Cu(NO3)2, and atacamite for CG CuCl2. The materials were then exposed to ammonia vapors to test the effectiveness of their entrapping property. All materials proved to be very efficient and rapid in the uptake of ammonia which invariably results in the formation of a Cu(II)/NH3 complex. However, after a few tens of minutes, CG Cu(NO3)2 and CG CuCl2 release water and get wet, thereby resulting unsuitable for applications. Only CG CuSO4 keeps dry for at least 25 hours. This makes it a valid candidate for building devices for trapping ammonia and possibly other gases capable of interacting with Cu (II). The entrapment of ammonia by this material was also characterized by 1H and 29Si MAS-NMR XAS spectroscopies.

2020 - A new material based on montmorillonite and Cu(II)-phenanthroline complex for effective capture of ammonia from gas phase [Articolo su rivista]
Castellini, E.; Malferrari, D.; Bernini, F.; Bighi, B.; Mucci, A.; Sainz-Diaz, I. C.; Serrano, A.; Castro, G. R.; Brigatti, M. F.; Borsari, M.
abstract

The intercalation of [Cu(Phen)(H2O)2]2+ (CuPhen) in montmorillonite (Mt) produces a stable hybrid material that is very efficient in removing NH3 from gas phase even at extremely low pressures. The process was studied by elemental analysis, X-ray powder diffraction, thermal analysis coupled with evolved gas mass spectrometry and DR UV–Vis, NMR and X-ray absorption spectroscopy. The adsorption of CuPhen on Mt consists of two consecutive steps. During the first one, CuPhen intercalates alone into Mt through a cation exchange process, afterwards CuPhen and SO42− ions entry jointly into the mineral interlayer. The two-steps adsorption process is described by a VI-type isotherm, successfully fitted by two independent Frumkin isotherms. NH3 trapping is long-lasting, easy, fast even at extremely low gas pressure and reversible under mild conditions. Mt containing CuPhen always results well performant in removing ammonia from gas phase, but an appreciably higher adsorption capacity of NH3 is obtained when SO42− ion is absent from the interlayer. This hybrid montmorillonite is thus a promising material to be used in industrial or environmental contexts, as an efficient air-cleaner.

2020 - Interlayer-confined Cu(II) complex as an efficient and long-lasting catalyst for oxidation of H2s on montmorillonite [Articolo su rivista]
Castellini, E.; Bernini, F.; Sebastianelli, L.; Sainz-Diaz, C. I.; Serrano, A.; Castro, G. R.; Malferrari, D.; Brigatti, M. F.; Borsari, M.
abstract

Removal of highly toxic H2S for pollution control and operational safety is a pressing need. For this purpose, a montmorillonite intercalated with Cu(II)-phenanthroline complex [Cu[(Phen)(H2O)2]2+ (Mt-CuPhen) was prepared to capture gaseous H2S under mild conditions. This hybrid material was simple to obtain and demonstrated an outstanding ability to entrap H2S at room temperature, retaining high efficiency for a very long time (up to 36.8 g of S/100 g Mt-CuPhen after 3 months of exposure). Sorbent and H2S uptake were investigated by elemental analysis, X-ray powder diffraction measurements, diffuse reflectance (DR) UV–Vis and infrared spectroscopy, thermal analysis and evolved gas mass spectrometry, scanning electron microscopy equipped with energy-dispersive X-ray spectrometer, and X-ray absorption spectroscopy. The H2S capture was studied over time and a mechanism of action was proposed. The entrapping involves a catalytic mechanism in which [Cu[(Phen)(H2O)2]2+ acts as catalyst for H2S oxidation to S0 by atmospheric oxygen. The low cost and the long-lasting performance for H2S removal render Mt-CuPhen an extremely appealing trap for H2S removal and a promising material for many technological applications.

2020 - Tuning of halobenzenes uptake in montmorillonite from gas phase through a functionalization process involving Cu(II)-phenanthroline and heptanethiol [Articolo su rivista]
Castellini, Elena; Malferrari, Daniele; Bernini, Fabrizio; Bighi, Beatrice; Mucci, Adele; Sainz Diaz, Ignacio Claro; Serrano, Aida; Castro, German R.; Brigatti, Maria Franca; Borsari, Marco
abstract

In this paper, montmorillonite functionalized with a Cu(II)-phenanthroline complex (Mt-CuPhen) and then exposed to heptanethiol vapors (Mt-CuPhen-HPT) was tested for the capture of halobenzenes in gas phase. The treatment of Mt-CuPhen with heptanethiol vapors produced important compositional changes involving Cu(II) reduction, oxidation of thiol to disulfide and dehydration of the mineral interlayer space. Entrapping experiments were carried out on fluorobenzene, chlorobenzene and bromobenzene at 25 and 45°C. The hybrid material proved to be very efficient for all halobenzenes and especially for fluorobenzene. Observed performances are slightly affected by temperature. Halobenzene desorption occurred even at 100°C, a temperature quite lower than that required for decomposition of Mt-CuPhen-HPT. The Mt-CuPhen-HPT hybrid material, therefore, can be reused several times and requires low energy costs for regeneration. An alternative regeneration procedure based on disulfide removal has been proposed as well. Mt-CuPhen-HPT was extensively characterized before and after halobenzenes immobilization through elemental analysis, UV-Vis measurements, thermogravimetric analyses, FTIR, NMR and X-ray absorption spectroscopies.

2019 - Structural properties of adsorbent phyllosilicates rule the entrapping ability of intercalated iron-phenanthroline complex towards thiols [Articolo su rivista]
Castellini, E.; Malferrari, D.; Bernini, F.; Mucci, A.; Borsari, M.; Brigatti, M. F.
abstract

The interaction of volatile organic sulfur derivatives, such as 1-heptanethiol (C7H16S), with clay minerals treated with a μ-oxo Fe3+-phenanthroline 1:1 complex results strongly affected by crystal chemical properties of pristine mineral phases. In particular, two sepiolite clays with different structural features demonstrated significantly different ability to immobilize the Fe3+-phenanthroline complex at two pH values (pH = 5.4 and pH = 2.3). The most effective binding was obtained with sepiolite with higher structural disorder at pH 5.4. Accordingly, the resulting hybrid material showed also the greatest efficiency in removal of thiol in gas phase. A direct correlation can be established between the adsorption of the Fe3+-phenanthroline complex and the gas binding process at room temperature. In fact, 1-heptanethiol entrapping occurs via redox reactions between Fe3+ and a first thiol molecule to give the reduced Fe2+-phenanthroline complex and disulfide, followed by the binding of further thiols to the reduced metal centre. The extremely high amount of thiol immobilized by the hybrid material also suggests the co-presence of a catalytic mechanism that guarantees the reoxidation of Fe+2 to Fe+3 and the restoration of redox reactions with thiol. Investigation and conclusions were supported by the several experimental techniques: elemental analysis, X-ray powder diffraction analyses, UV–Vis measurements, FT-IR and NMR spectroscopies, thermogravimetric analyses.

2019 - Sulfur bearing and aromatic compound trapping by layered silicates: a great start for innovative technological applications [Abstract in Atti di Convegno]
Malferrari, D.; Bernini, F.; Bighi, B.; Borsari, M.; Brigatti, M. F.; Castellini, E.; Mucci, A.; Sebastianelli, L.
abstract

2019 - Trapping at the Solid-Gas Interface: Selective Adsorption of Naphthalene by Montmorillonite Intercalated with a Fe(III)-Phenanthroline Complex [Articolo su rivista]
Castellini, E.; Malferrari, D.; Bernini, F.; Sainz Diaz, C. I.; Mucci, A.; Sola, M.; Brigatti, M. F.; Borsari, M.
abstract

In this study, stable hybrid materials (Mt-Fe(III)Phen), made by the μ-oxo Fe(III)-phenanthroline complex [(OH 2 ) 3 (Phen)FeOFe(Phen)(OH 2 ) 3 ] 4+ (Fe(III)Phen) intercalated in different amounts into montmorillonite (Mt), were used as a trap for immobilizing gaseous benzene and naphthalene and their mono chloro-derivatives at 25 and 50 °C. The entrapping process was studied through elemental analysis, magic angle spinning NMR spectroscopy, thermal analysis, and evolved gas mass spectrometry. Naphthalene and 1-chloronaphthalene were found to be immobilized in large amount at both temperatures. Molecular modeling allowed designing of the structure of the interlayer in the presence of the immobilized aromatic molecules. Adsorption is affected by the amount of the Fe complex hosted in the interlayer of the entrapping hybrid materials. On the contrary, under the same conditions, benzene and chlorobenzene were not adsorbed. Thermal desorption of naphthalenes was obtained under mild conditions, and immobilization was found to be reversible at least for 20 adsorption/desorption cycles.

2018 - Chemical trapping of gaseous H⁠2S at high and low partial pressures by an iron complex immobilized inside the montmorillonite interlayer [Articolo su rivista]
Malferrari, Daniele; Castellini, Elena; Bernini, Fabrizio; Serrano Rubio⁠, Aida; Rafael Castro, German; Ignacio Sainz-Díaz⁠, Claro; Caleffi, Matteo; Brigatti, Maria Franca; Borsari, Marco
abstract

A stable hybrid material (Mt-Fe(III)Phen) formed by intercalation of the μ-oxo Fe(III)-phenanthroline complex [(OH⁠2)⁠3(Phen)FeOFe(Phen)(OH⁠2)⁠3]⁠4+ (Fe(III)Phen) in montmorillonite (Mt) is able to immobilize H⁠2S in gaseous phase with high efficiency even at extremely low pressures. DR UV–vis and I.R. spectroscopies, elemental analysis, X-ray powder diffraction, thermal analysis coupled with evolved gas mass spectrometry, and X-ray absorption spectroscopy show that the material has high adsorption capacity, performs fast H⁠2S trapping and is long-lasting. Moreover, even extremely low levels of H⁠2S can be removed easily and quickly from gaseous phase using a suitable amount of the trapping material. The immobilization mechanism likely involves a redox reaction between iron (III) and one S⁠2− ion, followed by the binding of a second S⁠2− ion to the metal centre. The process takes place at room temperature, is reversible for several cycles, and does not require pre-treatment of neither gaseous H⁠2S nor the adsorbent material. Therefore, this modified montmorillonite is a promising material to get rid of H⁠2S in processes of environmental interest and to obtain gaseous (and gasifiable) high quality hydrocarbons in fuels refineries.

2018 - Experimental and Theoretical Investigation of Intercalation and Molecular Structure of Organo-Iron Complexes in Montmorillonite [Articolo su rivista]
Sainz-Díaz, C. I.; Bernini, F.; Castellini, E.; Malferrari, D.; Borsari, M.; Mucci, A.; Brigatti, M. F.
abstract

The intercalation of the μ-oxo Fe(III)-phenanthroline 1:1 complex [(OH2)3(Phen)FeOFe(Phen)(OH2)3]+4 inside montmorillonite yielded a nanostructured material with strong and selective entrapping ability toward thiol molecules and hydrogen sulfide. In this work, experiments and computational molecular modeling by means of quantum mechanical calculations has been applied to study the molecular structure and interactions between this complex and the interlayer of montmorillonite. This approach allowed the identification of the geometrical disposition of the complexes inside the interlayer, the characterization of the hydration and coordination water molecules, and the explanation of the physico-chemical properties of these functionalized materials. The antiferromagnetic spin configuration of the Fe(III) ions results in the most stable state. Two conformers of the complex have been considered, having the phenanthroline rings in twisted or in parallel planes, respectively, and the transition of one conformer into the other has been explored by molecular dynamics simulations. The conformer with phenanthroline rings in parallel planes is found to be the favored species for intercalation in montmorillonite. Both experimental nuclear magnetic resonance analysis and adsorption isotherms are consistent with the modeling results. Different complex amount, equal and double of the cation exchange capacity (CEC) of montmorillonite, and hydration states inside the interlayer have been investigated reproducing faithfully the experimental d(001) spacing of the montmorillonite in the different conditions. The complex molecules intercalated over the CEC of montmorillonite adopt a disposition of the phenanthroline rings perpendicular to that of the complex already introduced by cation exchange.

2017 - Baseline studies of The Clay Minerals Society Source Clay montmorillonite STx-1b [Articolo su rivista]
Castellini, Elena; Malferrari, Daniele; Bernini, Fabrizio; Brigatti, Maria Franca; Castro, German Rafael; Medici, Luca; Mucci, Adele; Borsari, Marco
abstract

For more than forty years, The Clay Minerals Society has dispensed a set of source clays which have enabled a large number of researchers to work on identical materials. Many of these source clays remained unchanged over the years but, conversely, other clays have gone out of stock and thus were replaced. This was the fate of montmorillonite STx-1a, which was replaced by STx-1b. Although STx-1a and STx-1b share many basic chemical and mineralogical features, some minor differences exist that can affect behavior. A baseline characterization of the source clay STx-1b, which was the objective of this study, was, therefore, necessary to provide researchers a tool useful not only for new investigation but also to compare new results obtained on STx-1b with literature data on STx-1a. This characterization was gained using traditional and advanced methods that include: 1) chemical composition (major and trace elements); 2) cation exchange capacity determination; 3) thermal analyses coupled with evolved gas mass spectrometry; 4) quantitative mineralogical characterization using powder X-ray diffraction and Rietveld-RIR (Reference Intensity Ratio) refinement; 5) X-ray absorption spectroscopy at the Fe K-edge; 6) diffuse reflectance ultraviolet-visible and infrared spectroscopies; 7) 29Si, 27Al, and 1H magic-angle spinning nuclear magnetic resonance measurements. According to this multi-analytical approach, the montmorillonite chemical formula is [4](Si7.753 Al0.247) [6](Al3.281 Mg0.558 Fe0.136 Ti0.024 Mn0.002) [12](Ca0.341 Na0.039 K0.061) O20 (OH)4.

2017 - Crystal chemical characterization and computational modeling of a μ-oxo Fe(III) complex with 1,10-phenanthroline clarify its interaction and reactivity with montmorillonite [Articolo su rivista]
Brigatti, Maria Franca; Díaz, Claro Ignacio Sainz; Borsari, Marco; Bernini, Fabrizio; Castellini, Elena; Malferrari, Daniele
abstract

This work provides a systematic study of the μ-oxo-di-fac-[triaqua-(1,10-phenanthroline-κ2N,N′)-iron(III)]bis(sulfate), [(OH2)3(phen)FeOFe(phen)(OH2)3] (SO4)2 (phen = phenanthroline). Crystal structure is determined by single-crystal X-ray diffraction data and refined to R = 0.039. The crystal structure is monoclinic (Z = 2), space group P21 with unit cell dimensions a = 8.5157(3), b = 17.6434(5), c = 9.9678(3) Å, β = 90.133(2)°, V = 1497.62(8) Å3. The triaqua(1,10-phenanthroline)iron(III) parts are linked through one oxo-bridge. Both Fe(III) cations show a distorted octahedral coordination. The single-crystal data are complemented by computational chemistry modeling at quantum mechanical level, X-ray powder diffraction at room and high temperature conditions and by thermal analysis. Molecular modeling suggests that the role of the crystallization water molecules is critical to establish the intermolecular interactions for the stability of the crystal structure.

2017 - Effective and Selective Trapping of Volatile Organic Sulfur Derivatives by Montmorillonite Intercalated with a μ-oxo Fe(III)-Phenanthroline Complex [Articolo su rivista]
Bernini, Fabrizio; Castellini, Elena; Malferrari, Daniele; Castro, German Rafael; Sainz Díaz, Claro Ignacio; Brigatti, Maria Franca; Borsari, Marco
abstract

The mu-oxo Fe(III) phenatithroline Complex [(OH2)(3)(Phen)FeOFe(Phen) (OH2)(3)](+4) intercalated in montmorillonite provides a stable hybrid material. In this study, the ability and efficiency of this material to immobilize thiols in gas phase, acting as a trap at the solid-gas interface, were investigated. Aliphatic thiols containing both hydrophilic and hydrophobic end groups were chosen to test the selectivity of this gas trap. DR-UV vis, IR, elemental analysis, thermal analysis and evolved gas mass spectrometry, X-ray powder diffraction, and X-ray absorption spectroscopy techniques were employed to characterize the hybrid material before and after thiol exposure and to provide information on the entrapping process. Thiol immobilization is very large, up to 21% w/w for heptanethiol. In addition, evidence was obtained that immobilization occurs through the formation of a covalent bond between the iron of the complex and the sulfur of the thiol. This provides an immobilization process characterized by a higher stability with respect to the method's based on physi-adsorption. Thiol immobilization resulted thermally reversible at least for 20 adsorption/desorption cycles. Unlike standard desulfurization processes like hydrotreating and catalytic oxidation which work at high temperatures and pressures, the present system is able to efficiently trap thiols at room temperature and pressure, thus saving energy. Furthermore,we found that the selectivity of thiol immobilization can be tuned acting on the amount of complex intercalated in montmorillonite. In particular, montmorillonite semisaturated with the complex captures both hydrophobic and hydrophilic thiols, while the saturated montmorillonite shows a strong selectivity toward the hydrophobic molecules.

2016 - An alternative method of calculating cleavage energy: The effect of compositional domains in micas [Articolo su rivista]
Brigatti, Maria Franca; Elmi, Chiara; Guggenheim, Stephen; Malferrari, Daniele; Poppi, Marco
abstract

Cell parameters and atomic coordinates for the true micas are varied to simulate layer deformation along the [001]* direction by an external force. The resulting (deformed) structures are then used to determine bonding forces and to calculate a maximum force component along the [001]*. Bonding forces are compared to experimental observations of bond lengths of the interlayer, octahedral, and tetrahedral sites. Calculated bonding forces are consistent with experimental observations that locate the cleavage plane along the interlayer. Because many studies have shown that the chemical composition of the cleavage surface often differs from the structure of the bulk, compositional variations were considered in determining cleavage energy. The chemical composition of the cleavage surface may produce a reduction in cleavage energy. This reduction in energy depends on various elements occurring in greater number at the cleavage surface than in the bulk. A reduction in cleavage energy occurs if there is a reduction in the interlayer site size, as measured by the area defined by the first-coordination basal oxygen atoms. In addition, a reduction in lateral cell dimensions and an increase in the bonding force between the basal oxygen atoms and the interlayer cation also results in a reduction in cleavage energy in the direction normal to the layer. Joins considered are phlogopite–annite, tetra-ferriphlogopite–tetra-ferri-annite, polylithionite– siderophyllite, muscovite–celadonite, and muscovite–paragonite. A lack of homogeneity in composition may produce preferential cleavage locations within the family of (001) planes. The cleavage energy appears to be greater for homogeneous synthetic micas compared to natural micas.

2016 - Pre-amyloid oligomers budding:a metastatic mechanism of proteotoxicity [Articolo su rivista]
Bernini, Fabrizio; Malferrari, Daniele; Pignataro, Marcello; Bortolotti, Carlo Augusto; DI ROCCO, Giulia; Lancellotti, Lidia; Brigatti, Maria Franca; Kayed, Rakez; Borsari, Marco; Del Monte, Federica; Castellini, Elena
abstract

The pathological hallmark of misfolded protein diseases and aging is the accumulation of proteotoxic aggregates. However, the mechanisms of proteotoxicity and the dynamic changes in fiber formation and dissemination remain unclear, preventing a cure. Here we adopted a reductionist approach and used atomic force microscopy to define the temporal and spatial changes of amyloid aggregates, their modes of dissemination and the biochemical changes that may influence their growth. We show that pre-amyloid oligomers (PAO) mature to form linear and circular protofibrils, and amyloid fibers, and those can break reforming PAO that can migrate invading neighbor structures. Simulating the effect of immunotherapy modifies the dynamics of PAO formation. Anti-fibers as well as anti-PAO antibodies fragment the amyloid fibers, however the fragmentation using anti-fibers antibodies favored the migration of PAO. In conclusion, we provide evidence for the mechanisms of misfolded protein maturation and propagation and the effects of interventions on the resolution and dissemination of amyloid pathology.

2015 - Effect of crystal chemistry and cation ordering on cleavage processes of dioctahedral micas: petrogenetic implications [Articolo su rivista]
Brigatti, Maria Franca
abstract

Knowledge of the atomic arrangement of the topmost surface of micas is basic for the understanding of a large number of surface phenomena and interacting processes on the Earth's crust. Crystal structure of micas at the surface shows relaxation and reconstruction phenomena such as variation of coordination number for the interlayer cation and compositional variation from the composition of the bulk. These evidences support the hypothesis that small interlayer cations cluster at the cleavage plane and that a lack of homogeneity of the layers constituting the mica structure may produce preferential cleavage locations.

2015 - Stepwise structuring of the adsorbed layer modulates the physico-chemical properties of hybrid materials from phyllosilicates interacting with the μ-oxo Fe+3-phenanthroline complex [Articolo su rivista]
Bernini, Fabrizio; Castellini, Elena; Malferrari, Daniele; Borsari, Marco; Brigatti, Maria Franca
abstract

The -oxo Fe+3-phenanthroline 1:1 complex [(OH2)3(Phen)FeOFe(Phen)(OH2)3]+4 (hereafter Fe+3Phen) was successfully immobilized on montmorillonite (Mt) and kaolinite (Kt) minerals. Adsorption data on both minerals described an adsorption isotherm of VI type and were successfully fitted using two independent Frumkin isotherms. The interaction between the complex and the minerals is strong and yields two stable hybrid materials: Kt-Fe+3Phen and Mt-Fe+3Phen. DR UV-Vis, elemental analysis, TGA-MSEGA, temperature-controlled XRPD techniques were used to characterize the structural properties of the hybrid materials. These investigations showed that the Fe+3Phen adsorption occurs stepwise via the formation of a bilayer structure. The first layer is the result of a cation exchange process involving the negative charges of the mineral while the second one probably forms through stacking interaction and/or sulphate ions bridging. XRD diffraction measurements show that in Mt the second layer formation is accompanied by a super- structuring of the interlayer that changes the thermal and chemical properties of the composite material. In particular, interesting catalytic properties are observed in Mt-Fe+3Phen samples, but they are completely suppressed with the formation of the Fe+3Phen bilayer structure.

2015 - Trioctahedral Fe-rich micas: Relationships between magnetic behavior and crystal chemistry [Articolo su rivista]
Brigatti, Maria Franca; Affronte, Marco; Elmi, Chiara; Malferrari, Daniele; Laurora, Angela
abstract

Six Fe-bearing mica samples with different Fe ordering, Fe2+/(Fe2++Fe3+) ratio, octahedral, and tetrahedral composition were studied. Four micas belong to the phlogopite-annite join (space group C2/m), two are Mg-rich annite and two are Fe-rich phlogopite, one is a tetra-ferriphlogopite (space group C2/m) and one is Li-rich siderophyllite (space group C2). Thus these samples had a different environment around the Fe cations and layer symmetry. These micas were characterized by chemical analyses, single-crystal X-ray diffraction, X-ray absorption spectroscopy, and magnetic measurements. In samples with Fe mostly in octahedral coordination, dominant magnetic interactions among Fe atoms are ferromagnetic, which reach a maximum at higher Fe2+/(Fe2++Fe3+) ratios. Samples with higher Fe2+/(Fe2++Fe3+) ratio are also characterized by higher values of the Curie-Weiss theta constant. Where Fe2+/(Fe2++Fe3+) ratios decrease, theta values also decrease. The Fe3+-rich phlogopite shows predominant Fe3+ in tetrahedral coordination and shows anti-ferromagnetic interactions with a negative value of the Curie-Weiss theta constant (i.e., theta = 25 K). Fe ordering in octahedral trans- and in one of the two cis-sites accounts for a greater theta value in Li-rich siderophyllite when compared to other samples showing similar octahedral Fe content. Our data suggest that Fe3+ cations and other non-ferromagnetic cations hinder long range magnetic ordering. This observation may produce for the different role of octahedral Fe magnetic interactions that can in principle develop along long Fe-rich octahedral chains, when compared to tetrahedral-octahedral interactions that are confined within the layer by the non-ferromagnetic cations of the interlayer. Spin glass behavior is indicated by the dependency of the temperature to produce maxima in the susceptibility curve. These maxima are related to the frequency of the applied AC magnetic field.

2014 - CRYSTAL CHEMISTRY AND SURFACE CONFIGURATIONS OF TWO IRON-BEARING TRIOCTAHEDRAL MICA-1M POLYTYPES [Articolo su rivista]
Elmi, Chiara; Brigatti, Maria Franca; Guggenheim, S.; Pasquali, Luca; Montecchi, Monica; Nannarone, Stefano
abstract

The aim of this paper is to explore the crystal chemical features of both the bulk and the uppermost surface layers of two trioctahedral Fe-rich mica-1M (space group C2/m) polytypes: a tetra-ferriphlogopite from an alkali-carbonatic complex near Tapira (Belo Horizonte, Minas Gerals, Brazil) and a Fe2+-bearing phlogopite also containing Fe3+ in tetrahedral sites from the Kovdor carbonatite-bearing alkaline-ultrabasic complex (Kola Peninsula, Russia). The chemical formulae are [XII](K0.99) [VI](Fe2+0.08 Fe3+0.15 Mg2.76 Ti0.01) [IV](Fe3+0.82 Si3.18) O10.37 (F0.24 OH1.39) and [XII](K0.94 Na0.06) [VI](Fe2+0.17 Fe3+0.05 Mg2.75 Mn0.01 Ti0.05) [IV](Fe3+0.16 Al0.84 Si3.00) O10.21 (F0.35 OH1.44) for tetra-ferriphlogopite and Fe-bearing phlogopite, respectively. The two minerals show a pronounced difference in tetrahedral composition, where Fe for Si substitution is at 20.5% in tetra-ferriphlogopite and at 4% in Fe-bearing phlogopite. Fe3+ substitution produces an increase of the tetrahedral sheet thickness and of mean tetrahedral edge lengths in tetra-ferriphlogopite with respect to Fe-bearing phlogopite. The tetrahedral rotation angle (α) changes remarkably from tetra-ferriphlogopite (α = 10.5°) to the Fe-bearing phlogopite (α = 8.5°), thus indicating a significantly greater tetrahedral ring distortion in the tetra-ferriphlogopite with respect to the Fe-bearing phlogopite. The interconnection between α and tetrahedral flattening angle () may indirectly suggest the variation of  due to Fe for Si tetrahedral substitution. Crystal chemical modifications at the mineral surface were investigated via X-ray Photoelectron Spectroscopy by comparing data related to the surface to data originating from the bulk. The local population at the anionic position can be obtained by considering that the binding energy of photoelectron peaks is dependent on the chemical state of atoms and their local environment. If oxygen is substituted by fluorine, the binding energy of Mg was observed to shift to higher values. By considering the Mg1s binding energies of tetra-ferriphlogopite and Fe-bearing phlogopite, Mg is preferentially coordinated to F and not to OH groups. This is consistent with higher BE values observed for Fe-rich phlogopite characterized by higher F content with respect to tetra-ferriphlogopite.

2014 - Crystal chemistry and surface configurations of two polylithionite-1M crystals [Articolo su rivista]
Elmi, Chiara; Brigatti, Maria Franca; Guggenheim, S.; Pasquali, Luca; Montecchi, Monica; Nannarone, S.
abstract

This paper explores the crystal chemical features of the bulk and the outermost (001) surface layers of two trioctahedral Li-rich mica-1M (space group C2) polytypes, i.e. a polylithionite (MLG-114) from Li-mica granitic pegmatite at St. Austell (SW England) and a Fe2+-rich polylithionite (Ch-140) from a rhyolite at Profitis Ilias, Chios Island, Greece. Structural formulae are [xii](K0.952Na0.019Rb0.019) [vi](Al1.034Li1.459Fe2+0.389Fe3+0.046Mn0.038Mg0.002Zn0.002Ti0.001) [iv](Al3+0.477 Si3.523)O10.081(F1.735OH0.184) and [xii](K0.992Na0.014) [vi](Al0.980Li1.028Fe2+0.787Fe3+0.022 Mn0.059Mg0.052Zn0.010Ti0.024) [iv](Al3+0.857Si3.143) O10.095 (F1.617 OH0.288) for MLG-114 and Ch-140, respectively. Each mineral is characterized by a high F content in the anion site and has tetrahedral and octahedral compositions related to the exchange vector [vi]Li-1[iv]Si-1 [vi]Fe2+ [iv]Al. Unit cell dimensions are a = 5.251(1), b = 9.066(2), c = 10.087(2) Å; β = 100.694(5)° for polylithionite MLG-114 and a = 5.282(1), b = 9.121(3), c = 10.080(3) Å; β = 100.764(5)° for Ch-140. Crystal structure refinements (agreement factors are R = 3.58% and R = 3.75% for MLG-114 and Ch-140, respectively) demonstrate that the [vi]Li-1[vi]Fe2+ [iv]Si-1[iv]Al exchange vector produces a decrease in the lateral dimensions of the tetrahedral and octahedral sheets. The decrease in basal oxygen distances results from the effect of the strain caused by the orientation of opposing tetrahedral sheets within a 2:1 layer. The decrease reduces the strain so that the basal oxygen plane can remain nearly planar. Changes in these dimensions via distortions of the tetrahedral basal-oxygen ring (α = 3.3° and α = 4.1° for MLG-114 and Ch-140, respectively) are limited. Octahedral M1 and M3 sites are similar in size and much larger than M2 and the mean electron count is M3 < M1 < M2 in MLG-114 and M1  M2 < M3 in Ch-140. Al preferentially occupies the M2 site, whereas Fe and Li are nearly disordered between M1 and M3 sites with a slight preference of Fe for the M1 site in MLG-114 and for M3 site in Ch-140. Element concentrations on the (001) surface, obtained through X-ray photoelectron spectroscopy (XPS) high-resolution spectra for Si2p, Al2p, Fe2p, K2p, Li1s, and F1s core levels, indicates that a greater amount of lithium and a smaller amount of potassium characterize the surface with respect to the bulk. The decrease in K content, commonly observed in micas, is related to its location on the cleavage surface, because the cation must be distributed equally between the two (001) surfaces generated upon cleavage. The increase in Li content on or near the (001) cleavage surface suggests a preference for cleavage near lithium-enriched regions. The surface structure of the polylithionite crystals suggests that Al, Li, and Fe cations maintain coordination features at the surface similar to the bulk. Silicon, however, which is generally in four-fold coordination, shows also a small number of [1]-fold coordinated components at a binding energy of 99.85 eV.

2013 - IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) [Articolo su rivista]
Galli, Ermanno; Brigatti, Maria Franca; Malferrari, Daniele; Sauro, Francesco; De Waele, Jo
abstract

2012-056 ROSSIANTONITE Al3(PO4)(SO4 )2(OH)2(H2O)14 Triclinic Space group: P1 a = 10.3410(5) b = 10.9600(5) c = 11.1446(5) Å α = 86.985(2) β = 65.727(2) γ = 75.064(2)º V = 1110.49(9) Å3 Z = 2

2013 - Open-field experimentation of an innovative and integrated zeolitite cycle: Project definition and material characterization [Articolo su rivista]
Malferrari, Daniele; Laurora, Angela; Brigatti, Maria Franca; M., Coltorti; D. D., Giuseppe; B., Faccini; Passaglia, Elio; Vezzalini, Maria Giovanna
abstract

This study is a part of the European LIFE +2010 Project "ZeoLIFE - Water pollution reduction and water saving using a natural zeolitite cycle". It characterizes the application of Italian zeolite-rich pyroclastic rocks (zeolitites) as soil conditioner. Laboratory experiments will be tested on an experimental field in the Codigoro area, Ferrara district (North-East Italy). The samples investigated are chabazite- and phillipsite-rich and are all collected in quarries from Central Italy: (1) Grosseto area (Sorano and Sovana); (2) Viterbo area (Farnese, Grotte Santo Stefano, Corchiano, Nepi), and (3) Rome area (Riano). All samples are characterized by more than 30 % of zeolite content, together with volcanic glass, feldspars, pyroxenes, and micas. The quantitative mineralogical characterization of soil samples from Codigoro shows variable proportions of quartz, illite, plagioclase, K-feldspar, calcite, dolomite, chlorite, serpentine, kaolinite, gypsum together with an amorphous residual. Collected data confirm that conditioning of soils with selected zeolitite can be extremely promising for a well evident improvement of the soil quality, and contribute to define a standard approach which can surely find a general application well above the boundaries of the selected area for the field test. © 2013 Accademia Nazionale dei Lincei.

2013 - Rossiantonite, Al3(PO4)(SO4)2(OH)2(H2O)10•4H2O, a new hydrated aluminum phosphate-sulfate mineral from Chimanta massif, Venezuela: Description and crystal structure [Articolo su rivista]
Galli, Ermanno; Brigatti, Maria Franca; Malferrari, Daniele; Sauro, F.; De Waele, J.
abstract

Rossiantonite, ideally Al3(PO4)(SO4) 2(OH)2(H2O)10·4H 2O, triclinic (space group P1̄), a = 10.3410(5), b = 10.9600(5), c = 11.1446(5) Å, α = 86.985(2), β = 65.727(2), γ = 75.064(2)°, V = 1110.5(1) Å3, Z = 2, is a new mineral from the Akopan-Dal Cin cave system in the Chimanta massif (Guyana Shield, Venezuela). The mineral occurs as small (≤0.15 mm) and transparent crystals in a white to slightly pink fine-grained sand, filling spaces between boulders of weathered quartz sandstone. Associated phases are gypsum, sanjuanite, rare alunite, quartz and micro-spherules of amorphous silica. Rossiantonite is colorless with a white streak and vitreous luster. The mineral is brittle with irregular to sub-conchoidal fracture and it shows a poorly developed cleavage. Rossiantonite is biaxial and not pleochroic, with mean refractive index of 1.504. The calculated density is 1.958 g/cm3. Electron microprobe analyses, with H2O measured by thermogravimetric analysis, provided the following empirical formula based on 28 O apfu: Al2.96Fe 0.03P1.01S2H30.02O 28. The five strongest lines in the X-ray powder diffraction pattern, expressed as d (Å), I, (hkl) are: 4.647, 100, (210); 9.12, 56, (100); 4.006, 53, (220); 8.02, 40, (110); 7.12, 33, (011). The crystal structure, refined using 3550 unique reflections to R = 0.0292, is built of PO4 and Al O6 polyhedral rings, creating complex chains parallel b by sharing the OH-OH edge belonging to the Al(3) polyhedron. Three symmetrically independent Al sites can be identified, namely: Al(1), Al(2), and Al(3). Tetrahedral sites, occupied by P, share all their apexes with AlO6 octahedra. Unshared octahedral apexes are occupied by water molecules. Four additional water molecules are placed in between the previously identified chains. Two oxygen tetrahedra, occupied by S atoms, are connected along the chains by means of weak hydrogen bonding. The rossiantonite structure shows similarities with minerals belonging to the sanjuanite-destinezite group.

2013 - Sodian muscovite-2M1: crystal chemistry and surface features [Articolo su rivista]
Elmi, Chiara; Brigatti, Maria Franca; Guggenheim, S.; Pasquali, Luca; Montecchi, Monica; Malferrari, Daniele; Nannarone, Stefano
abstract

his study explores crystal chemical features of a sodian muscovite from Antarctica, both in the bulk of the mineral and at the uppermost surface layers. These features may support a deeper comprehension of processes affecting mineral surface and mineral physical properties. The muscovite under analysis is characterized by limited celadonite and paragonite substitutions and shows the following chemical formula: [XII](K1.73 Na0.27) [VI](Fe2+ 0.14 Al3+ 3.77 Mg 0.07 Ti0.01) [IV](Al1.91 Si6.09) O20 (F0.11 OH3.89). The sample is monoclinic, 2M1 polytype, with symmetry C2/c and unit cell parameters a = 5.1969(1), b = 9.0138(3), c = 20.0835(7) A, and β = 95.763(2)°. The two tetrahedral sites, T1 and T2, present similar distances (>T1.O< = 1.643A and >T2.O< = 1.647 A) and distortion parameter values, evidencing a disordered distribution of Si and Al at tetrahedral sites. The tetrahedral ring is significantly distorted (α = 11.2°) and the tetrahedral basal oxygen atom plane is remarkably wavy (δz = 0.224 A).Crystal chemical modifications at mineral surface were investigated by X-ray photoelectron spectroscopy. The interlayer cation K is eight-fold coordinated both in the bulk and at the surface, and its amount decreases at the surface. Sodium substitutes K and its coordination at the mineral surface is six. This evidence, together with a significant Na increase at the surface, is consistent with Na clustering close to the cleavage plane.

2013 - Use of zeolitites from Central Italy in an integrated cycle aimed at water and chemical fertilizers saving (ZEOLIFE – LIFE+10ENV/IT/000321) [Abstract in Atti di Convegno]
Brigatti, Maria Franca; Laurora, Angela; Malferrari, Daniele; Passaglia, Elio; Vezzalini, Maria Giovanna
abstract

Introduction The project “ZEOLIFE - Water pollution reduction and water saving using a natural zeolitite cycle” has been conceived to test an innovative integrated zeolitite application having the aim to reduce the NH4 content in livestock effluents and correct agricultural soils, with improvement of the yield and economization of water for irrigation and fertilizers. This project leads to a reduction of fresh and groundwater pollution and avoids excessive exploitation of the water resource. For further details visit the website www.zeolife.it. The first goal of the project was to carry out a chemical and physical, as well as mineralogical characterization of several zeolitite samples, coming from different quarries located in Central Italy, in order to select the most suitable raw material to be used throughout the entire project. Samples from the following seven localities were analyzed: Sorano (Gr), Sovana (Gr), Farnese (Vt), Grotte Santo Stefano (Vt), Corchiano (Vt), Nepi (Vt), and Riano (Rm). All the mentioned localities are the closest to the experimental field (Codigoro, Ferrara); in each quarry non-marketable material, namely broken blocks or blocks with irregular shape and size, is available. This material represents an already available reserve of zeolitic tuff that best fit the purposes of this project. Besides the technological properties of the raw material, the final choice also took into account factors of environmental (e.g. carbon footprint) and economic (e.g, cost, full and immediate availability) concern. Experimental In order to obtain representative samples from each examined locality, an appropriate procedure was followed by picking out a total amount of 10 kg of raw material from different points of the quarries. The collected material was accurately ground, and repeatedly quartered until obtaining the needed sample amount. Quantitative mineralogical analyses were carried out using the Rietveld method via the General Structure Analysis System (GSAS) software package [1], combined with the Reference Intensity Ratio (RIR) method for the determination of the amorphous phase [2]. Whole rock chemical analysis was carried out on pressed pellets via a wavelength-dispersive X-Ray Fluorescence (XRF). Loss On Ignition (LOI) was determined by sample heating in a oven at 1100°C. CEC determination of exchanged Ca2+, Mg2+, Na+, and K+ cations was achieved via Atomic Absorption Spectrometer (AAS) measurements. Apparent density was determined as the ratio between the mass of ground sample which fills a measuring cup in loose conditions and the volume of the cup. Water retention was determined using a modified Campbell’s methods [3]. Results and discussion As demonstrated by plenty of experimental scientific works (e.g., [4] for a review), chabazite is very effective not only in NH4 uptake from swine manure, but also in successive controlled NH4 release in soils. Other zeolite species, such as phillipsite, have great potential for 244 NH4 adsorption and retention, but not the same capacity as chabazite in exchanging NH4 with circulating solutions and plant root systems in soils. A comparison between samples from studied quarries is reported in Fig. 1. As can be observed the Sorano zeolitite shows the best features (e.g., high zeolite content and high CEC).

2012 - Channel Sediment Characterization and Evaluation of the Potential Impact of Iron-Rich Phases on the Use of Sediments in Brick Production [Articolo su rivista]
Malferrari, Daniele; Laurora, Angela; Elmi, Chiara; Brigatti, Maria Franca; L., Medici; M. C., Zeqireja
abstract

Using data collected at both room temperature and higher temperatures, this study examined the mineralogy of, and iron coordination shell in, polluted sediments from drainage and irrigation channels. As a part of the study, mineralogical characteristics of iron phases of canal sediments were examined to determine if these sediments could be used in place of common clays for the production of bricks. While such use would reduce the impact of these wastes on the environment, an excess of iron in these sediments could affect some important features of bricks. Therefore, this study examined the oxidation state of iron as well as its structural location in the mineral matrix. X-ray powder diffraction, thermal analysis, and X-ray absorption spectroscopy were used to examine sediments and bricks manufactured from irrigation and drainage channels of the Po River region in northeast Italy. Results indicated that canal sediments can be used as row materials in clay brick production. In fact, the process temperature (950°C) that characterized brick production was similar to the temperature used for thermal treatment of polluted sediments in this study.

2012 - Magnetic behavior of trioctahedral micas with different octahedral Fe ordering [Articolo su rivista]
Pini, Stefano; Brigatti, Maria Franca; Affronte, Marco; Malferrari, Daniele; A., Marcelli
abstract

This contribution is finalized at the discussion of the magnetic structure of two samples, belonging to phlogopite–annite [sample TK, chemical composition IV(Si2.76Al1.24) VI(Al0.64Mg0.72 Fe1.452+ Mn0.03Ti0.15) (K0.96Na0.05) O10.67 (OH)1.31 Cl0.02] and polylithionite–siderophyllite joints [sample PPB, chemical composition IV(Si3.14Al0.86)VI(Al0.75Mg0.01 Fe1.032+ Fe1.033+ Mn0.01Ti0.01Li1.09) (K0.99Na0.01) O10.00 (OH)0.65F1.35]. Samples differ for Fe ordering in octahedral sites, Fe2+/(Fe2+ + Fe3+) ratio, octahedral composition, defining a different environment around Fe cations, and layer symmetry. Spin-glass behavior was detected for both samples, as evidenced by the dependency of the temperature giving the peak in the susceptibility curve from the frequency of the applied alternating current magnetic field. The crystal chemical features are associated to the different temperature at which the maximum in magnetic susceptibility is observed: 6 K in TK, where Fe is disordered in all octahedral sites, and 8 K in PPB sample, showing a smaller and more regular coordination polyhedron for Fe, which is ordered in the trans-site and in one of the two cis-sites.

2012 - Structure and Mineralogy of Clay Minerals. Bergaya and Lagaly ed. Handbook of Clay Science, Chapter 2. [Capitolo/Saggio]
Brigatti, Maria Franca; Galan, Emilio; Theng, Bkg
abstract

Phyllosilicates, and among them clay minerals, are of great interest not only for the scientific community but also for their potential applications in many novel and advanced areas. However, the correct application of these minerals requires a thorough knowledge of their crystal chemical properties. This chapter provides crystal chemical and structural details related to phyllosilicates and describes the fundamental features leading to their different behaviour in different natural or technical processes, as also detailed in other chapters of this book. Phyllosilicates, described in this chapter, are minerals of the (i) kaolin-serpentine group (e.g. kaolinite, dickite, nacrite, halloysite, hisingerite, lizardite, antigorite, chrysotile, amesite, carlosturanite, greenalite); (ii) talc and pyrophyllite group (e.g. pyrophyllite, ferripyrophyllite); (iii) mica group, with particular focus to illite; (iv) smectite group (e.g. montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite); (v) vermiculite group; (vi) chlorite group; (vii) some 2:1 layer silicates involving a discontinuous octahedral sheet and a modulated tetrahedral sheet such as kalifersite, palygorskite and sepiolite; (viii) allophane and imogolite and (ix) mixed layer structures with particular focus on illite-smectite.

2011 - Crystal chemistry and surface features of a 2M1 paragonitic muscovite [Abstract in Rivista]
Elmi, Chiara; Brigatti, Maria Franca; Pasquali, Luca; Montecchi, Monica; Nannarone, Stefano; Malferrari, Daniele
abstract

The paragonitic muscovite considered [XII](K1.722 Na0.251 Ba0.010) [VI](Fe2+0.140 Al3+3.769 Cr3+0.003 Mg0.074 Ti0.012 Mn0.002) [IV](Al1.897 Si6.103) O20 (F0.109 OH3.891) came from Antarctica, it is monoclinic, 2M1 polytype, with symmetry C2/c and unit cell parameters a = 5.1969(1), b = 9.0138(3), c = 20.0835(7) (Å) and β = 95.763(2) (°).By using a multi-analytical approach this study describes the crystal chemical features of muscovite determined both in the bulk and on the uppermost surface layers. The bulk structure was refined by single crystal X-ray diffraction and the final refinement yielded the following agreement factor R = 0.0299. The two tetrahedral sites, T1 and T2, present similar distances (<T1-O> = 1.643 Å and <T2-O> = 1.647 Å) and distortion parameter values, thus evidencing a disordered distribution of [IV]Si and [IV]Al in tetrahedral sites. Tetrahedral ring is significantly distorted (α = 11.2°) and the tetrahedral basal oxygen atoms plane is remarkably wavy (Δz = 0.224Å). tetrahedral ring distortion affects not only the topology of the cleavage plane, but also the coordination of the interlayer cation, which reduces from twelve to eight. Crystal chemical modifications at mineral surface were investigated via X-ray Photoelectron Spectroscopy (XPS), by comparing data related to surface to the ones characterizing the bulk. A peculiarity of muscovite from Antarctica is a limited Na for K interlayer substitution, which was found in the bulk as well as on the mineral surface. It is well known that in micas the coordination of the interlayer cation can vary from twelve to six, depending on the distortion of the hexagonal tetrahedral ring, as measured by  angle, as observed and predicted by Weiss et al. [1].The interlayer cation K (binding energy = 293.36 eV) is confirmed to be eight-fold coordinated [2]. Na (binding energy = 1071.02 eV) substitutes K both in the bulk and at the surface. Na coordination, at mineral surface, reduces from eight to six [3]. The six-fold coordination presented by Na is consistent with  ≈ 16°, which is typical for paragonite, whose interlayer is completely occupied by Na. Chemical composition at the surface was compared to bulk chemical composition obtained by electron microprobe analysis. This comparison highlights a decrease in K content, which can be explained by its location on the cleavage surface, since the cation is expected to be distributed equally along the two surfaces generated after cleavage, and an increase in Na which can be related to Na domains close to the cleavage surface.These aspects may relate muscovite cleavage processes to the presence of “defects”, or better in-homogeneities in layer crystal chemistry. This fact may thus suggest that Na content in paragonitic muscovite could not be only attributed to a solid solution mechanism, where this cation substitutes for K, but rather to the presence of Na-dominant clusters.

2011 - Crystal chemistry of Ti-rich fluorophlogopite from Presidente Olegario, Alto Paranaiba igneous province, Brazil [Articolo su rivista]
E., Schingaro; M., Lacalamita; F., Scordari; Brigatti, Maria Franca; G., Pedrazzi
abstract

Trioctahedral micas from kamafugitic lavas of Presidente Olegario (Brazil) are Ti-Fe-bearing fluorophlogopites. They were investigated using a combination of electron probe microanalysis (EPMA), single-crystal X-ray diffraction (SCXRD), and Mössbauer spectroscopy.EPMA data yielded the following ranges: Al2O3 (8.7–10.1 wt%), MgO (19.6–20.6 wt%), FeO (5.7–6.5 wt%), TiO2 (5.9–7.5 wt%), K2O (8.9–9.7 wt%), Na2O (0.4 –0.6 wt%), and fluorine (3.4–4.1 wt%). Mössbauer investigation indicated: VIFe2+ ∼ 60%, VIFe3+ ∼ 10%, IVFe3+ ∼ 30%. X-ray analysis indicated the 1M polytype, with cell parameters in the range a = 5.3208–5.3376, b = 9.2210–9.2464, c = 10.1227–10.155 Å, β = 100.157–100.194°. Structure refinements using anisotropic displacement parameters were performed in space group C2/m and converged to 2.01 ≤ R1 ≤ 3.51, 2.00 ≤ wR2 ≤ 3.51%.The micas have no VIAl3+ and Na is probably partitioned over both interlayer and octahedral sites. Major substitutions are OH− ↔ F−, and the Ti-oxy substitution: VIM2+ + 2(OH)− ↔ VITi4+ + 2O2– + H2↑. Accordingly, the structural features of the studied micas encompass those typical of both fluorophlogopites and micas affected by Ti-oxy substitution

2011 - Crystal chemistry of lizardite-1T from Northen Apennines Ophiolites (Italy) [Abstract in Rivista]
Laurora, Angela; Brigatti, Maria Franca; Malferrari, Daniele; Galli, Ermanno; Rossi, Antonio; M., Ferrari
abstract

This study investigates the crystal chemical features of six lizardite-1T crystals sampled in four ophiolitic outcrops (Pompeano, Sassomorello, Varana, and Santa Scolastica) in the Modena Apennines (Italy).Notwithstanding the extensive contributions already present in literature, this is the first study dealing with lizardites from Modena ophiolites. As evidenced by one of our samples, the whole rock composition affects lizardite composition, which results to be sensible to the overprint of secondary, metasomatic events. In our study, particular attention was devoted to the effects of octahedral Fe for Mg and of Si-1Al(Mg,Mn,Fe)2+-1 (Al,Cr,Fe)3+ exchange mechanisms on the structure. Our results suggest that Fe for Mg substitution induces an increase in the octahedral M-O4 length, and a decrease in the octahedral site distortion. Both these effects are also observed to influence unit-cell parameter c. The effect of the Si-1 Al(Mg,Mn,Fe)2+-1(Al,Cr,Fe)3+ substitution is a decrease in the M-O1 distance and a concomitant increase in the T-O1 distance.

2011 - Determination of Hg binding forms in contaminated soils andsediments: state of the art and a case study approachingabandoned mercury mines from Mt. Amiata (Siena, Italy) [Articolo su rivista]
Malferrari, Daniele; Brigatti, Maria Franca; Elmi, Chiara; Laurora, Angela
abstract

This paper, after an introduction about the state of the art in the methods for the evaluation of Hg chemical speciation,focuses on Hg polluted soils and sediments from Siele mining area (Piancastagnaio, Siena, Italy). In particular, the mineralogicalcomposition was evaluated via X-ray powder diffraction, total Hg was determined via inductively coupled plasma optical emissionspectroscopy on acid digested samples, and Hg binding forms were investigated both via sequential selective extraction andpyrolytic extraction. Solutions obtained via sequential selective extraction were checked for Hg content using inductively coupledplasma optical emission spectroscopy, whereas to carry out pyrolytic extraction a thermogravimetric analyser coupled with anevolved gas mass spectrometer was used. To our knowledge, this last method was never used for this purpose on natural samples.Experimental results enhance that: i) Hg detection via thermal analyses can qualitatively distinguish among different Hg compounds.ii) The temperature of Hg thermal release is affected by both the sample matrix and the Hg bond type. iii) Thermal analysesfail in the attempt of a quantitative determination of the evolved species; this goal is better achieved via the selective chemical leaching.iv) Most of the Hg is related to HgS-like bonds, thus pointing to the presence of very stable Hg compounds. v) Only in somesamples we found also organo-complexed Hg-like compounds and, in a limited amount, hydrosoluble Hg and/or Hg species solublein weakly acid environment. vi) No correlation between sampling point and both total Hg and/or Hg speciation was observed.

2011 - EMU Notes in Mineralogy - volume 11Layered mineral structures and their Application in Advanced Technologies [Curatela]
Brigatti, Maria Franca; A., Mottana
abstract

Layered mineral structures and their Application in Advanced Technologies

2011 - EMU School 2011 - Layered mineral structures and their applications in advanced technologies [Esposizione]
Brigatti, Maria Franca; A., Mottana
abstract

Scuola breve internazionale dedicata ai minerali a strati e alle loro applicazioni in ambito industriale, tecnologico e biologico. La scuola si rivolgeva a studenti, dottorandi e giovani ricercatori.

2011 - High-temperature vesuvianite: crystal chemistry and surfaceconsiderations [Articolo su rivista]
Elmi, Chiara; Brigatti, Maria Franca; Pasquali, Luca; Montecchi, Monica; Laurora, Angela; Malferrari, Daniele; Nannarone, Stefano
abstract

A multi-methodical approach has been appliedfor characterizing the bulk and surface crystal chemical featuresof a high-temperature vesuvianite crystal from skarns ofMount Somma-Vesuvius Volcano (Naples, Italy). Vesuvianitebelongs to the space group P4/nnc with unit cellparameters a = 15.633(1)A ° , c = 11.834(1)A ° and chemicalformula (Ca18.858 Na0.028 Ba0.004 K0.006 Sr0.005 h0.098)19.000(Al8.813 Ti0.037 Mg2.954 Mn0.008 Fe0.1142? Fe1.3753? Cr0.008B0.202)13.511 Si18.000(O0.261 F0.940 OH7.799)9.000. Structurerefinement, which converges at R = 0.0328, demonstrates astrong positional disorder down the fourfold axes, indicatingthat the Y1 site is split into two positions (Y1A and Y1B)alternatively occupied. However, because of X4 proximity toY1B and Y1A, X4 cannot be occupied if Y1B or Y1A are.OverallY1 occupancy (Y1A ? Y1B) reaches approximately0.5, as common in vesuvianite and occupancy of Y1B site isextremely limited. Moreover, T1 position, limitedly occupied,accommodates the excess of cations generally related toY position. A small quantity (0.202 apfu) of boron is sited atthe T2 site that, like T1, is poorly occupied. The determination of the amount of each element on the (100)vesuvianite surface, obtained through X-ray photoelectronspectroscopy high-resolution spectra in the region of the Si2p,Al2p, Mg1s, and Ca2p core levels, evidences that a greateramount of aluminum and a smaller amount of calciumcharacterize the surface with respect to the bulk. Althoughboth of these features require further investigation, we mayconsider the Al increase can be related to preferential orientationof Al-rich sites on the (100) plane. Furthermore, thesurface structure of vesuvianite suggests that Al, Ca, and Mgcations maintain coordination features at the surface similarto the bulk. Silica, however, while presenting fourfold coordination,shows also a [1]-fold small coordinated componentat binding energy 99.85 eV, due to broken Si–O bonds at thesurface. The presence of eight- and nine-coordinated Cacations is suggested by a large XPS feature resulting from themerging of Ca2p3/2 and Ca2p1/2 peaks at 348.45 and352.05 eV, respectively.

2011 - Layer charge location in 2:1 layer silicates as key factor for controlling pollutant dynamics in natural environments [Relazione in Atti di Convegno]
Brigatti, Maria Franca
abstract

2011 - Layer charge location in layer silicates and its implications [Abstract in Rivista]
Elmi, Chiara; Brigatti, Maria Franca; Malferrari, Daniele
abstract

Layer charge value and location are commonly considered key factors for predicting interaction of layer silicates with external agents, such as, for example, pollutants, bio-molecules, and, more generally, ionic complexes. Several methods are discussed in literature for the experimental determination of layer charge, always, however, giving an average value from the different micro-crystals used for the analysis. The most commonly used methods are: the structural formula method [1, 2], the alkylammonium method [3] and the potassium saturation method [4]. The purpose of this paper is to demonstrate that the determination of the average value of the layer charge can sometimes lead to inconsistent results, as not correctly representing the layer charge location at mineral surface. This goal was achieved by analyzing crystal chemical results obtained from different crystals of muscovite characterized by a different content of celadonitic substitution. Muscovite sometimes presents heterovalent substitutions both in tetrahedral (e.g., Al3+ for Si4+) and in octahedral sites (e.g., Mg2+, Fe2+, and vacancies for Al in octahedral sites). Our results seem to demonstrate that these substitutions can be ascribed to trioctahedral cells, all occupied by cations different than Al, in a dominating dioctahedral pattern, with cis-octahedral sites entirely occupied by Al and the trans-site vacant. This interpretation suggests that mean layer charge may not represent effective layer charge at mineral surface because it refers not to randomly distributed substitution, but to domains showing different chemistry which can be locally charge-neutralized. Furthermore, also distortion parameters which affect tetrahedral topology and that can also affect the formation of surface complexes, such as alpha angle and delta z oxygen plane flattening, can be different inside a same structure and locally not corresponding strictly to the determined mean value via single crystal diffraction.

2011 - PREFACE TO EMU Notes in Mineralogy 11: Layered Mineral Structures and their Application in Advanced Technologies [Prefazione o Postfazione]
Brigatti, Maria Franca; A., Mottana
abstract

non disponibile

2011 - Quantitative local structure determination in mica crystals: ab initio simulations of polarization XANES at the potassium K-edge [Articolo su rivista]
Xu, W.; Chen, D.; Chu, W.; Wu, Z.; Marcelli, A.; Mottana, A.; Soldatov, A.; Brigatti, Maria Franca
abstract

An attempt to refine the local structure of a layered structure such as mica is made by combining angle-resolved XANES (AXANES) and single-crystal X-ray diffraction (SC-XRD) experiments. Ab initio calculations of AXANES spectra of several tri-octahedral micas have been used to further interpolate experimental data and to deduce physico/chemical effects. Structural distortions have been found highly correlated with the compositional disordering that arises from electronic interactions between anions and cations, and extend the interlayer entering deep into nearby tetrahedral and octahedral sheets. Multiple occupations at the same atomic site have been investigated in detail both in the parallel and perpendicular components of AXANES spectra. Finally, the best fit obtained, computed in the framework of the multiple-scattering theory, is presented and the limitations of the muffin-tin potential in layered systems are briefly discussed.

2011 - Sessione J7 - I siti anionici nei fillosilicati: implicazioni cristallografiche, cristallochimiche e petrologiche [Altro]
Brigatti, Maria Franca; A., Mottana; A., Pavese; R., Sassi; F., Scordari
abstract

Sessione tematica tenutasi il 23 settembre 2011 all'interno del congresso Geoitalia2011 - VIII Forum Italiano di Scienze della Terra.

2011 - Sodium hexametaphosfate interactions with illite and montmorillonite: preliminary observation on thermal behavior [Abstract in Rivista]
Castellini, Elena; M., Bert; C., Berthold; Brigatti, Maria Franca; Malferrari, Daniele
abstract

The interaction of an efficient deflocculant, sodium hexametaphosphate (NaHMP), with two different illites (IMt-1 from Silver Hill, Montana USA and from Schwäbisch Hall, Würtenberg Germany) and two different Ca-montmorillonites (STx-1 from Gonzales County, Texas, USA and from Santa Rita, New Mexico, USA) was investigated.Adsorption measurements of the NaHMP anion were performed onNa-exchanged illite IMt-1 as a function of temperature by means of inductively coupled plasma technique (I.C.P.). The thermodynamic parameters of the adsorption process, together with an estimation of the maximum adsorbed amount on the Na-illite were obtained and compared to the corresponding data previously obtained for Na-kaolinite.The effect of NaHMP on the natural illites and montmorillonites was analyzed using different techniques. I.C.P. measurements of the concentration of P, Na, Si, Al, Ca, Mg, and K of the deflocculant solutions in contact with the clays were performed in order to detail the adsorption, dissolution and exchange phenomena which accompany the deflocculant activity.Thermal analysis (thermo-gravimetric, thermal-differential) and XRD measurements at non ambient temperature conditions were used to characterize the clay solid samples after the interaction with NaHMP.Thermo-gravimetric analyses indicate that NaHMP-treated illites and montmorillonites are less hydrated than natural samples, whereas the dehydroxilation reaction seems to be not influenced by the NaHMP treatment. Basal periodicity was measured via XRPD diffraction on (00l) oriented mounts of the air-dried samples in the temperature range 25 - 400°C (heating rate 2 °C/min) using a powder diffractometer equipped with an area detector. No significant variation of layer periodicity was observed, thus indicating that NaHMP molecules are adsorbed on the edge and/or in the interlayer without modifying natural layer periodicity.

2011 - Structure and mineralogy of layer silicates: recent perspectives and new trends [Relazione in Atti di Convegno]
Brigatti, Mf; Malferrari, D; Laurora, A; Elmi, C
abstract

Because of their many novel and advanced applications, there is increasing interest in layer silicates from the scientific and technical communities. Appropriate application of these minerals requires deep understanding of their properties and of the processes where they are involved. This chapter, by providing fundamental definitions and crystal structural and chemical data pertaining to layer silicates, aims to introduce this field to new researchers and technicians, by describing the fundamental features leading to different behaviours of layer silicates in different natural or technical processes. The subject addressed is vast and so the reader is referred in some cases to work already published. The focus here is on layer silicates for which detailed crystal structures are given in the literature and which are likely to be used in an applied way in the future. Layer-silicate minerals fulfilling these requirements are: (1) kaolin-serpentine group (e. g. kaolinite, dickite, nacrite, halloysite, hisingerite, odinite, lizardite, berthierine, amesite, cronstedtite, nepouite, kellyite, fraipontite, brindleyite, guidottiite, bementite, greenalite, caryopilite; minerals of the pyrosmalite series); (2) talc and pyrophyllite groups (e. g. pyrophyllite, ferripyrophyllite, willemseite); (3) mica group (i.e. some recent advances in crystal chemistry and structure of dioctahedral and trioctahedral micas); (4) smectite group (e. g. montmorillonite, saponite, hectorite, sauconite, stevensite, swinefordite); (5) vermiculite group; (6) chlorite group (e. g. trioctahedral chlorite such as clinochlore, di,trioctahedral and dioctahedral chlorites such as cookeite and sudoite); (7) some 2: 1 layer silicates involving a discontinuous octahedral sheet and a modulated tetrahedral sheet such as kalifersite, palygorskite and sepiolite; and (8) imogolite and allophane.

2011 - Textural study of metamorphic rocks by means of a conventional X-ray source [Abstract in Rivista]
Malferrari, Daniele; Brigatti, Maria Franca; Laurora, Angela; R., Sassi; F. P., Sassi
abstract

The aim of this study is the textural characterization of very low togreenschist facies metamorphic rocks by means of a conventional X-ray source, possibly establishing a relationship between the extent of morphological orientation of mineral grains and metamorphic degree.For a long time geologists investigated the morphological orientation of mineral grains in polycrystalline rocks by means of petrographic microscope equipped with a Universal stage. More recently diffraction of conventional X-ray sources as well as diffraction (or transmission) of hard X-rays, electrons and neutrons has been applied to these kind of study.However, whereas X-ray conventional sources can be regarded as a routine technology, hard X-ray, electron and neutron sources are only available in a few facilities around the world.Phyllosilicates such as smectite, illite, muscovite, chlorite and biotite play a key role in the textural characteristics of the mineral assemblages of rocks characterized by increasing metamorphic degree. The present study is focused on the variation of the X-ray intensities of selected reflections of these phases. In short, if a morphologic orientation of the grains of a certain phyllosilicate is present, a variation of the intensity of these reflections will be measured when the rock sample is rotated in a goniometer keeping constant both the incident beam angle and the position of the detector.The samples selected for the study are the following: 1) a Ms, Chl, Qtz, Pl fine grained metapelite from Frassenetto (UD, Italy) (very low grade metamorphism, Anchizone) with some detrital muscovite flakes recognizable by their coarser grain size; 2) Ms, Chl, Qtz, Pl fine grained metapelite from Chiadenis (UD, Italy) (low grade metamorphism, Epizone) with some detrital muscovite flakes recognizable by their coarser grain size; 3) a Ms, Chl, Ilm, Qtz, Pl layered phyllite from Villabassa (BZ, Italy) (Greenschist facies metamorphism, Ms-Chl-Bt), with crenulated main foliation and axial planes defining a second spaced foliation; 4) a Ms, Bt, Grt, Ilm, Qtz, Pl layered phyllite from Luson (BZ, Italy) (Greenschist facies metamorphism, Ms-Bt-Grt), with crenulated main foliation and axial planes defining a second spaced foliation.

2011 - The crystal chemistry of lizardite-1T from Northern Apennines ophiolites near Modena, Italy [Articolo su rivista]
Laurora, Angela; Brigatti, Maria Franca; Malferrari, Daniele; Galli, Ermanno; Rossi, Antonio; Ferrari, M.
abstract

We investigated the crystal-chemical features of six crystals of lizardite-1T sampled in four outcrops of ophiolite, atPompeano, Sassomorello, Varana, and Santa Scolastica, in the Modena Apennines, Italy. In spite of the extensive contributionsalready present in the literature, this is the first study dealing with lizardite from the Modena ophiolites. As is clear from one ofour samples, the whole-rock composition affects the composition of lizardite, which makes it susceptible to overprinting by latermetasomatic events. In our study, we paid particular attention to the effects of VIMg–1VIFe2+ and of IVSi–1 IVAl VI(Mg, Mn, Fe)2+–1VI(Al, Cr, Fe)3+ exchange mechanisms on the structure. Our results suggest that VIMg–1VIFe2+ substitution induces an increase inthe M–O4 length in octahedra and a decrease in the octahedral-site distortion. Both these effects are also observed to influencethe unit-cell parameter c. The effect of the IVSi–1 IVAl VI(Mg, Mn, Fe)2+–1 VI(Al, Cr, Fe)3+ substitution is to decrease the M–O1distance and concomitantly, to increase the T–O1 distance.

2010 - Crystal chemistry and structure of clay minerals [Altro]
Brigatti, Maria Franca
abstract

Sessione tematica organizzata nell'ambito del convegno IMA 2010 tenutosi a Budapest (Ungheria) dal 21 al 27 agosto 2010.

2010 - Crystal chemistry, surface morphology and X-ray photoelectron spectroscopy of Fe-rich osumilite from Mt. Arci, Sardinia (Italy) [Articolo su rivista]
Elmi, Chiara; Brigatti, Maria Franca; Pasquali, Luca; Montecchi, Monica; Laurora, Angela; Malferrari, Daniele; Nannarone, Stefano
abstract

Microprobe anal., single crystal X-ray diffraction, XPS, at. force microscopy, and X-ray absorption spectroscopy were applied on Fe-rich osumilite from the volcanic massif of Mt. Arci, Sardinia, Italy. Osumilite belongs to the space group P6/mcc with unit cell parameters a = 10.1550(6), c = 14.306(1) Å and chem. formula (K0.729)C (Na0.029)B (Si10.498 Al1.502)T1 (Al2.706 Fe0.2942+)T2 (Mg0.735 Mn0.091 Fe1.1842+)AO30. Structure refinement converged at R = 0.0201. Unit cell parameter a is related to octahedral edge length as well as to Fe2+ content, unlike the c parameter which does not seem to be affected by chem. compn. The detn. of the amt. of each element on the mineral surface, obtained through XPS high-resoln. spectra in the region of the Si2p, Al2p, Mg1s and Fe2p core levels, suggests that Fe presents Fe2+ oxidn. state and octahedral coordination. Two peaks at 103.1 and 100.6 eV can be related to Si4+ and Si1+ components, resp., both in tetrahedral coordination. The binding energy of Al2p, at 74.5 eV, indicates that Al is mostly present in the distorted T2 site, whereas the Mg peak at 1,305.2 eV suggests that this cation is located at the octahedral site. X-ray absorption at the Fe L2,3-edges confirms that iron is present in the mineral structure, prevalently in the divalent state and at the A octahedral site.

2010 - Effect of temperature on Hg-cysteine complexes in vermiculite and montmorillonite [Abstract in Atti di Convegno]
Malferrari, Daniele; Brigatti, Maria Franca; Marcelli, A.; Chu, W.; Wu, Z.
abstract

This work describes the influence of temperature on two Hg(II)-cysteine modified clay minerals with different layer charge (i.e.,vermiculite and montmorillonite) by using chemical analyses,thermal analyses coupled with evolved gas mass spectrometry(TGA-MSEGA), synchrotron-based X-ray absorptionspectroscopy (XAS), and X-ray powder diffraction (XRPD)techniques. These two latter techniques were applied onsamples heated “in situ” up to 900°C. Hg binds cysteine by thethiol group with Hg–SH bond lengths similar in both clayminerals, thus suggesting their independence from layer charge.On the contrary, the thermal behaviour of the adsorbedorganometallic complexes is strictly layer charge dependent, asevidenced by decomposition temperatures, which are commonlylower in montmorillonite than in vermiculite. Results from Xrayabsorption near edge structure (XANES) spectroscopyevidence a nearly completely Hg removal in montmorillonite attemperature values ranging from 600 to 700°C, unlike invermiculite where Hg is still present at these temperatures.

2010 - Effect of temperature on Hg-cysteine complexes in vermiculite and montmorillonite [Articolo su rivista]
Malferrari, Daniele; Brigatti, Maria Franca; Marcelli, A.; Chu, W.; Wu, Z.
abstract

This study describes the influence of temp. on two Hg(II)-cysteine modified clay minerals with different layer charges (i.e., montmorillonite and vermiculite) by using chem. and thermal analyses coupled with evolved gas mass spectrometry (TGA-MSEGA), synchrotron-based X-ray absorption spectroscopy (XAS), and X-ray powder diffraction (XRPD) techniques; these two latter techniques were applied on samples heated "in situ" up to 900 °C. Hg bonds cysteine by the thiol group with Hg-SH bond lengths similar in both clay minerals, thus suggesting their independence from layer charge. On the contrary, the thermal behavior of the adsorbed organometallic complexes was strictly layer charge dependent, as evidenced by decompn. temps., which were lower in montmorillonite than in vermiculite. Results from X-ray absorption near edge structure (XANES) spectroscopy evidenced nearly complete Hg desorption in montmorillonite between 600 and 700 °C, unlike in vermiculite where Hg was still present at these values.

2010 - Relationship between morphological preferred orientations and landslides [Abstract in Atti di Convegno]
Bortolotti, D.; Brigatti, Maria Franca; Elmi, Chiara; Malferrari, Daniele; Pattuzzi, Edda
abstract

Crystals orientation in polycrystalline natural compounds maybe either completely random or else follow preferred directions,which reflect physical processes in which the materials havebeen involved during the solidification and / or after the solidstate had been reached.The preferred orientation can be divided into two maingroups: i) preferred orientation of the crystal lattice (LPO,lattice preferred orientation) and ii) grains preferred orientation(i.e., morphological preferred orientations, MPO). Frequentlythere is a close relationship between these two groups.Geological processes that determine the formation of LPO are,for example, tectonic (regional) compressive movements; on theother hand MPO can be induced also by local stress (i.e.,gravitational movements). While tectonic (regional)compressive movements may produce LPO even on alreadylithified rocks, usually, MPO are induced only on not-lithifiedand incoherent rocks.The preferred orientation cab be observed: i)macroscopically (the rock structures) ii) microscopically, grainsorientation and morphological textures of the rock according tothe classic concept of optical microscopy, iii) with diffractionmethods (i.e., X-rays and neutrons diffraction), to study bothLPO and MPO when, this last, cannot be studied via opticalmethods because, for example, of a very small grain size.This research will investigate MPO via X-ray diffractiononly. We collected, and kept oriented, samples in severallandslide areas. In particular samples were collected both in theactive crumbling area and at the landslide margin. Sampleswere analyzed for texture using X-ray diffractometer equippedwith a phi-chi Eulerian cradle. We analyzed the preferredorientation of the hkl reflections: i) (001) and (060) in smectitiand illite; ii) (001) and (100) in caolinite; iii) (24-1) inplagioclase.Preliminary investigation demonstrated a direct correlationbetween the number of MPO and the amount of clay minerals.Texture measurements on samples collected in the crumblingarea agree with other morphological field measurements,providing, in addition to the main direction of the landslide, alsothe vertical module, thus probably defining the preferential pathfor interstitial fluids migration. Only in one case we couldobserve preferred orientation in a sample coming from a marginof a landslide, data which could testify a past movement (paleolandslide) or else a quiescent landslide.

2010 - Surface structure of natural muscovite [Abstract in Atti di Convegno]
Elmi, Chiara; Brigatti, Maria Franca; Malferrari, Daniele; Castro, G. R.; Ferrer Escorihuela, P.
abstract

The aim of this project is to study the atomic surface structure of a natural muscovite crystal thanks to the synchrotron radiation light and the grazing incidence X-ray diffraction (GIXRD).The muscovite studied [(K0.92Na0.08) (Al1.86Fe3+0.01Mg.0.07 Fe2+0.06Ti0.02) (Si3.03Al0.97) O10 F0.09 (OH)1.91] is monoclinic, 2M1 polytype, with symmetry C2/c and unit cell parameters a = 5.19690(10) b = 9.0138(3) c = 20.0835(7) (Å) and β = 95.763(2) (°).The muscovite structure was refined by single crystal X-ray diffraction and the final refinement yielded the following agreement factor R = 0.0299. The difference Fourier map shows a significant residual electron density (2.2-) close to the position related to M1 site, thus indicating that the excess of octahedral cations is located at M1. M1-O mean bond distance is 2.247(9) and M2-O distance is 1.929.Grazing incidence X-ray diffraction (GIXRD) was recently performed at SpLine at ESRF. This type of analysis is very useful to identify typical structural features of the surface, such as possible imperfections, relaxations or reconstructions. Usually, the atoms on surfaces, and sometimes those as deep as several layers down, assume positions different from their equilibrium positions in the bulk. Generally mineral surfaces will not be reconstructed unless they have been heated to temperature higher than 100 °C. In our case, the muscovite surface has been exposed to a delay of the first layer in order to study a freshly cleaned surface and data collected by GIXRD confirm that on muscovite surface only a relaxation occurs from an equivalent plane in the bulk. This is a common case for minerals with a low-symmetry structure as the feldspar surface.

2010 - The interlayer structure of trioctahedral lithian micas: An AXANES spectroscopy study at the potassium K-edge [Articolo su rivista]
Cibin, G.; Mottana, A.; Marcelli, A.; Cinque, G.; Xu, W.; Wu, Z.; Brigatti, Maria Franca
abstract

We recorded angle-dependent XANES (AXANES) spectra at the potassium K-edge for three compositionally intermediate polylithionite-siderophyllite trioctahedral 1M-micas using polarized synchrotron radiation. We evaluated the exptl. spectra for both their in-plane and out-of-plane component fractions of the elec. dipole contribution using the anal. formulas of Brouder (1990), referring to theory to ext. the origin of their multiple-scattering pathways of Natoli et al. (2003). This anal. was extended to a fourth lithian mica studied previously and allowed characterization of the local environment and ordering around the potassium atoms in the interlayer of the entire set of micas. The AXANES in-plane components are notably similar to the XANES spectra recorded on randomly oriented powders, provided these are oriented at the "magic angle". Most obsd. contributions arise from multiple-scattering interactions of the photoelectron ejected from the potassium absorber colliding with atoms located in the interlayer itself. Note that this includes not only interactions with other coplanar potassium and/or alkali atoms distributed along the interlayer plane, but also with their near- and next-nearest neighboring oxygen atoms which lie on the basal planes of the tetrahedral sheets facing the interlayer. By contrast, the AXANES out-of-plane component suggests that several multiple-scattering pathways cross the energetic and structural barrier represented by the tetrahedral sheets. They reach not only the X anions that are located on the upper level of the octahedral sheets, at the center of the open cavity in the tetrahedral sheet, but also the metal cations centering the octahedral sheet itself. Therefore, the out-of-plane components provide indirect information on the no. of independent octahedral sites, the cation oxidn. state, and the trans- vs. cis-orientation of the anionic sites.

2010 - The relationships of bulk structure, surface structure, chemistry, and physical properties of mineral phases with six- and eight-membered silicate rings [Abstract in Atti di Convegno]
Elmi, Chiara; Brigatti, Maria Franca; Pasquali, Luca; Montecchi, Monica; Nannarone, Stefano; Laurora, Angela; Malferrari, Daniele
abstract

The goal of this research is to better understand the relationship between chemical composition and atomic structure (both bulk and surface structure) of minerals having six-membered silicate rings, such as osumilite and eight-membered silicate rings, such as vesuvianite. Osumilite under investigation occurs in thin fissures within a rhyolite from the volcanic massif of Mt. Arci, Sardinia (Italy). Vesuvianite sample is from skarns of Somma-Vesuvius volcano (Italy) instead.The osumilite and vesuvianite bulk structures were refined via single crystal X-ray diffraction. Osumilite sample is hexagonal, with symmetry P6/mcc and unit cell parameters a = 10.1550(6) c = 14.306(1) (Å). The structural formula is (K0.729)C (Na0.029)B’ (Si10.498 Al1.502)T1 (Al2.706 Fe2+0.219 Mg0.075)T2 (Mg0.660 Mn0.091 Fe2+1.258)AO30. When compared to literature data [1], osumilite sample from Mt. Arci is characterized by a significantly high Fe2+ content (1.478 apfu).X-ray photoelectron spectroscopy (XPS) enabled the crystal chemical characterization of osumilite surface, where iron was still observed in its divalent state, thus confirming a similarity in osumilite surface and bulk chemical composition. A further evidence of Fe oxidation state at osumilite surface is provided from X-ray absorption spectroscopy (XAS) at Fe-L2,3 edge.Vesuvianite is a complex tetragonal silicate. Vesuvianite ideal formula is Ca19(Al,Mg)13(B, Si)18O68(OH, O, F)10 and crystallizes, generally, in the space group P4/nnc. Vesuvianite presents in nature two different structural type: a high temperature type (at about 1000 °C) and a low temperature type (at about 900 °C). To recognize which type of vesuvianite, our sample belongs to, we studied its thermal decomposition via X-ray powder diffraction method by using a Philips X’Pert PRO diffractometer equipped with X’Celerator area detector. Finally we could assure that our sample is a high temperature vesuvianite with high symmetry P4/nnc.Unlike osumilite, vesuvianite surface is very complex to study because of its roughness on given faces of the crystal. However we could obtain preliminary information on the chemical composition of the surface via XPS and subsequently compare these data to bulk chemical composition. Moreover, unlike osumilite sample, vesuvianite presents Fe in octahedral site both in divalent and trivalent state, as confirmed by XAS experiments performed at the L2,3 edge of iron.

2010 - Trioctahedral micas: relationships between crystal chemistry and magnetic behavior [Abstract in Atti di Convegno]
Affronte, Marco; Brigatti, Maria Franca; Malferrari, Daniele; Marcelli, A.; Pini, S.
abstract

This study is aimed at verifying the factors affecting magneticsusceptibility χ variation in micas in relation to: I) Fe content;ii) Fe2+/Fe3+ ratio; iii) occurrence of Fe in tetrahedral andoctahedral sites, outlining possible ordering effects.Other aspects considered in our study will involve: i)eventually observed variation in magnetic properties forsamples showing similar chemical composition, but occurringfrom different areas and different crystallization environments;ii) possible influence of strong magnetic anomalies overmagnetic properties of samples therein occurring.All these aspects were thus addressed by characterizingsamples belonging to phlogopite – annite, tetra-ferriphlogopite– tetra-ferri-annite and polylithionite – siderophylliteseries. Some samples, representative of the whole sample set,were then selected for magnetic susceptibility characterization.Some of them also required calorimetric analyses, in order tobetter describe and understand their behaviour.Other experimental methods used in this investigationinclude: electron microprobe, structure resolution by X-raysingle crystal methods, X-ray absorption spectroscopy, with aparticular attention to the understanding of the XANES region.Main results demonstrate that: i) magnetic phenomenaassociated with maxima of magnetic susceptibility could beobserved at low temperature (T<10 K) and weak magnetic field(10 Oe); ii) magnetic properties depend not only on the total Fecontent. Samples where Fe is mostly in octahedral coordinationare predominantly ferromagnetic, strongly depending on the[6]Fe2+/([6]Fe2++[6]Fe3+) ratio, which was observed to increasewith Curie-Weiss θ constant (ranging from 13 to 24 K and from4.4 and 5.2 K for samples showing higher and lower[6]Fe2+/([6]Fe2++[6]Fe3+) ratio, respectively). In tetra-ferriphlogopite,dominant interactions were observed to be antiferromagnetic,as shown by a negative Curie-Weiss θ constantvalue (-25 K). Furthermore Curie-Weiss constant (θ) and thetemperature value giving the maximum in the magneticsusceptibility (Tm) seem to be dependent not only on the meannumber of Fe atoms in octahedral coordination (Z) per unit cell,but also on its ordering. Tm linearly depends on severalstructural parameters as well, e.g., the tetrahedral rotation angle α.

2010 - Use of perlite in combination with clays for the production of low environmental impact filter for heavy metals polluted aqueous solution [Abstract in Atti di Convegno]
Marchetto, Patrizia; Brigatti, Maria Franca; Laurora, Angela; Malferrari, Daniele
abstract

The aim of this work is to prepare a relatively cheap mixture ofperlite (a volcanic rock with intermediate composition betweenrhyolite and dacite) and clays, effective in the retention of heavymetals even after treatments at relatively high temperatures. Theobtained product could be possibly reused and therefore notdisposed of as toxic waste. The perlite used in this study comesfrom Greek quarries and is provided by the company "PerliteItaliana”. Three different types of clay materials were used: 1) aclay material coming from the Argille Varicolori formation; 2) acommercial bentonite (supplied by Laviosa, Italy; 3) a standardmontmorillonite (STx-1, from the County of Gonzales, Texas,USA), to be used as reference materials.Column and batch tests were carried out on several differentmixtures of the previously described materials in order toevaluate the effective adsorption of Cd, Pb, and Zn fromaqueous solution. Pb, Zn, and Cd contents of the “polluted”mixtures were thus measured via inductively coupled plasmaoptical emission spectroscopy (ICP-OES) after acid digestion.The obtained results indicate that the mixture consisting ofVaricolori clay and perlite can be profitably used as adsorbentof metals in solution. Adsorption data are consistent with thoseexpected from theoretical calculations.The method chosen for the permanent inertization ofpolluted samples is thermal treatment, which, as evidenced bynumerous literature data, can lead to a chemically inert product,eventually suitable for reuse in construction. Before being fired,each mixture was added from opportune amount of kaoliniteand feldspar. Release tests were, thus, carried out on firedproducts using weakly acid solution (pH values between 5.5.and 6) as leaching media. Results, which are very encouraging,are reported in the Table 1.

2010 - What drives the distribution in nature of 3T vs. 2M1 polytype in muscovites and phengites? A general assessment based on new data from metamorphic and igneous granitoid rocks [Articolo su rivista]
Sassi, R.; Brigatti, Maria Franca; Gomez Pugnaire, M. T.; Peruzzo, L.; Tellini, F.; Sassi, F. P.
abstract

Petrol., chem., and polytype data are presented for dioctahedral potassic micas from K-feldspar-bearing metamorphic and igneous rocks of acidic compn. unaffected by high-pressure (HP) conditions. The paper aims to demonstrate that: (1) under non-HP conditions, in both metamorphic and igneous plutonic environments, a given bulk-rock compositional constraint imposes a more or less marked phengitic compn. to dioctahedral potassic mica; and (2) this muscovite crystallizes as 2M1, notwithstanding its phengitic compn. The samples (157 in no.) are from widespread provenances. We conclude that the growth of 3T polytype of muscovite is not a function of mica compn. This is consistent with the recent crystallog. knowledge on polytypism, cation ordering, elastic properties, and structural deformational mechanisms of muscovite, which address the stabilization of 3T with pressure.

2009 - Al-saturated phlogopite: charge considerations and crystal chemistry [Articolo su rivista]
Bujnowski, T. J.; Guggenheim, S.; Brigatti, Maria Franca
abstract

Factors controlling the crystal structure of phlogopite have been widely investigated; but the role of electrostatic interactions, for example, has received much less attention than other factors. The purpose of the present study was to perform a single-crystal refinement of an Al-satd. phlogopite and to use that refinement to supplement crystal-chem. analyses. The phlogopite investigated was from the Rumford quadrangle, Maine, and has the following chem.: (K0.81Na0.03)Σ = 0.84(Mg1.84Fe2+0.52Al0.45Mn0.02Ti4+0.07)Σ = 2.90(Si2.78Al1.22)Σ = 4O10(OH1.81,F0.05)Σ=1.86. The sample is a 1M polytype with C2/m symmetry and cell dimensions of a = 5.3220(4), b = 9.2170(7), c = 10.2511(8) Å, and β = 100.081(1)°. Hydrogen atoms were located and the crystal structure was refined to give parameters R1 = 0.0301 and weighted R2 = 0.0887. The octahedral M1 site was larger than the M2 (av. M1-O: 2.079 Å, av. M2-O: 2.062 Å) and the electron counts were equal (M1 = M2 = 14.8 e-); based on bond distances, which are more accurate than electron counts in detg. occupancy; this result is consistent with a slight preference of Mg for M2 and Fe2+ for M1. Thirty-five Al-rich, natural phlogopite-1M samples that are of (1) high metamorphic grade, and that have (2) total Al contents ≥ 1.27 atoms per formula unit (a.p.f.u.), (3) Fe3+ contents ≤ 0.11 a.p.f.u., and (4) Mn contents ≤ 0.10 a.p.f.u. along with the newly described phlogopite, exhibited crystal chem. trends related to increasing Al content. Octahedral substitutions of smaller, high-charge cations (i.e. Al) apparently decrease distortions in the octahedral sites and produce longer M2-O4 distances. In addn., VIFe-F avoidance apparently occurs in high Al-content samples, which are generally high in VIFe. The data set also shows that these samples have limited ordering among M sites (Fe2+ in M1 and Al in M2), an increase in β (99.96° to 100.32°) possibly caused by cation ordering and therefore size differences of M1 and M2, and interlayer (A) sites with A-Oouter distances that increase and A-Oinner distances that decrease with increasing Ti content. Computer models were used to simulate electrostatic interactions in phlogopite structures with variable Al concns. utilizing Pauling's electrostatic valency principle, which considers first-coordination electrostatic interactions. The model results were compared to the max. Al concns. in natural and synthetic phlogopite samples. Model results revealed no indications (e.g. a limit reached or a sudden change occurred) that charge satn./undersatn. of the apical oxygen atoms at Al contents equal to the max. in natural and/or synthetic samples causes instability that could not be balanced by bond-length variation. However, a cation of higher charge substituting at M1 (or M2) may result in higher electrostatic repulsions between the other octahedral sites. Thus, the Al3+ content in the octahedral sites may reach a max., with Fe2+ for Mg substitutions favored.

2009 - Approvvigionamento idrico e manutenzione delle infrastrutture idrauliche di bonifica: il problema dello smaltimento dei sedimenti dei canali [Relazione in Atti di Convegno]
Malferrari, Daniele; Pistoni, Roberto; Laurora, Angela; Brigatti, Maria Franca; Mantovani, E.; Tonelli, F.
abstract

Questo studio si occupa dell’inquinamento dei sedimenti provenienti dal fondo dei canali situati nella parte settentrionale delle province di Modena e Ferrara (Italia). L’accumulo dei sedimenti (20 mm/anno ca.) è dovuto al drenaggio e alla canalizzazione delle acque per l’irrigazione. Per mantenere i canali in piena efficienza, i sedimenti devono essere periodicamente rimossi; se la concentrazione degli inquinanti (metalli pesanti) è superiore ai limiti di legge, i sedimenti devono essere stoccati alla stregua di rifiuti industriali. Tuttavia al momento non vi è un sito adeguato ad ospitare questa enorme quantità di sedimenti, e le amministrazioni locali non sarebbero in grado di affrontare i costi dello smaltimento. Il presente studio si propone di: i) effettuare una caratterizzazione approfondita dei sedimenti, ossia di determinare la speciazione chimica degli inquinanti in essi contenuti, per mezzo di una procedura di estrazione sequenziale e di analisi EXAFS, ed in questo modo, di valutarne il reale impatto ambientale; ii) mettere a punto un sistema per inertizzare i sedimenti inquinati e, allo stesso tempo, cercare un modo per re-impiegarli. Le analisi chimiche e le estrazioni sequenziali rivelano che lo Zn è il più ubiquitario ed abbondante tra i metalli pesanti, mentre Cd e Hg sono presenti in quantità molto limitate. Tutti i metalli pesanti esaminati (Cd, Cr, Cu, Hg, Ni, Pb and Zn) non sono facilmente rilasciati (piccole quantità sono adsorbite sulla superficie o nell’interstrato della smectite) ma neppure formano molecole stabili a lungo termine; infatti, le estrazioni sequenziali e le analisi EXAFS rivelano che i metalli pesanti sono soprattutto legati alla superficie di ossidi e idrossidi ed alla sostanza organica.Dall’analisi mineralogica risulta che I sedimenti sono principalmente costituiti da quarzo e minerali delle argille (smentite, clorite ed illite). Ad eccezione della materia organica, la cui presenza può essere drasticamente ridotta semplicemente immagazzinando i sedimenti in ambiente ossidante (ad esempio in atmosfera), la composizione mineralogica (e chimica) dei sedimenti è adeguata alla produzione di piastrelle e, soprattutto, di laterizi. Per mezzo di numerosi test finalizzati ad ottimizzare le procedure di produzione di piastrelle e laterizi, sono stati ottenuti risultati incoraggianti. I test di rilascio (leaching per mezzo di soluzioni acide) rivelano che tutti I metalli pesanti sono sostanzialmente trattenuti (il valore più elevato è quello del Cr, da 0.5 a 1.5μg/g).

2009 - CRYSTALLOGRAPHIC FEATURES AND CLEAVAGE NANOMORPHOLOGY OF CHLINOCHLORE: SPECIFIC APPLICATIONS [Articolo su rivista]
G., Valdré; Malferrari, Daniele; Brigatti, Maria Franca
abstract

This work firstly investigates the relationships between clinochlore cleavage characteristics, in terms of nano-morphology and surface potential, and its average crystal chemistry and topology. Secondly, it shows that the structural features of clinochlore can be successfully used to condense, order and self assemble complex biomolecules, such as DNA. A natural IIb-4 clinochlore [ symmetry, unit cell parameters a = 0.53301(4); b = 0.92511(6); c = 1.4348(1) (nm); alpha = 90.420(3); beta = 97.509(3); gamma = 89.996(4) (°)] with chemical composition (Mg1.701 Fe2+0.245 Ti0.004 Al0.998 Cr3+0.052) Mg3 (Si2.939 Al1.015 Fe3+0.046) O10 (OH7.913 F0.087) was selected. The octahedral sites of the silicate layer (<M(1) - O> = 0.2080 nm and <M(2) - O> = 0.2081 nm) are equal and occupied by Mg, whereas the octahedral sites in the interlayer M(3) and M(4) (<M(3) - O> = 0.2088 nm and <M(4) - O> = 0.1939 nm) show different size and are mostly completely occupied by divalent (Mg and Fe2+) and trivalent (Al3+) cations, respectively.The clinochlore cleaved surface presents two types of patterns: (i) stripe type (about 0.40 nm in height, up to several micrometers long and ranging from some nanometers to a few microns in lateral size), and (ii) triangular-saped-type (about 0.40 nm in height). Both features may result either from interlayer sheets whose cleavage weak directions are related to the different M(3) and M(4) site occupancy, or from interlayer weak bonding along specific directions to the underneath 2:1 layer. The cleaved surface, particularly at the cleaved edges, presents high DNA affinity, which is directly related to an average positive surface and ledge potential.

2009 - Combined mineralogical and EXAFS characterization of polluted sediments for the definition of technological variables and constraints [Abstract in Rivista]
Brigatti, Maria Franca; Elmi, Chiara; Laurora, Angela; Malferrari, Daniele; L., Medici
abstract

An extremely severe aspect, both from environmental and economic viewpoint, is the management of pollutedsediments removed from drainage and irrigation canals. Canals, in order to retain their functionality over the time,need to have their beds, periodically cleaned from sediments there accumulating. The management of removedsediments is extremely demanding, also from an economical perspective, if these latter needs to be treated asdangerous waste materials, as stated in numerous international standards. Furthermore the disposal of such a largeamount of material may introduce a significant environmental impact as well. An appealing alternative is the recoveryor reuse of these materials, for example in brick and tile industry, after obviously the application of appropriatetechniques and protocols that could render these latter no longer a threat for human health. The assessment ofthe effective potential danger for human health and ecosystem of sediments before and after treatment obviouslyrequires both a careful chemical and mineralogical characterization and, even if not always considered in the internationalstandards, the definition of the coordination shell of heavy metals dangerous for human health, as afunction of their oxidation state and coordination (e.g. Cr and Pb), and introducing technological constraints oraffecting the features of the end products. Fe is a good representative for this second category, as the features ofthe end product, such as color, strongly depend not only from Fe concentration but also from its oxidation state,speciation and coordination. This work will first of all provide mineralogical characterization of sediments fromvarious sampling points of irrigation and drainage canals of Po river region in the north-eastern of Italy. Sampleswere investigated with various approaches including X-ray powder diffraction under non-ambient conditions, thermalanalysis and EXAFS spectroscopy. Obtained results, and in particular EXAFS spectra were used to define andoptimize the technological variables of the recovery process.

2009 - Crystal chemistry of trioctahedral micas in the top sequences of the Colli Albani volcano, Roman Region, central Italy [Articolo su rivista]
Laurora, Angela; Malferrari, Daniele; Brigatti, Maria Franca; A., Mottana; E., Caprilli; G., Giordano; R., Funiciello
abstract

Trioctahedral mica crystals are frequently found in the volcanoclastic products emplaced during the final stages of the activity of the Colli Albani volcano (Roman Region, central Italy). In the youngest phreatomagmatic deposits, mica is found either as a minor mineral phase in holocrystalline ejecta, scoriae, and coherent pyroclastics, or as loose mica phenocrysts in incoherent pyroclastics. Based on optical and electron microscope investigations, as well as crystal chemical and structural data, the micas selected for this study were divided into two groups, the first one encompassing brownish, Fe-rich crystals (type-A phlogopites, hereafter referred as t-A) with 0.68 < Mg/(Mg+Fetotal) < 0.85 and 0.062 < Tiapfu < 0.199, and the other one encompassing colorless, Mg-rich crystals (type-B phlogopites, hereafter referred as t-B) with Mg/(Mg+Fetotal) in excess of 0.85 and 0.007 < Tiapfu < 0.052. t-A phlogopites also show a tetrahedral ring cavity, overlapped tetrahedral hexagon area, and basal tetrahedron area greater than in the t-B phlogopites.From a petrological point of view, the textural and chemical variations of t-A phlogopites are compatible with fractional crystallization processes taking place within the magma chamber. t-B phlogopites show evidence of a Ti-oxy substitution mechanism, thus suggesting high fO2 conditions. Textural and paragenetic features observed in t-B phlogopite-bearing rock samples, indicate a genesis by thermal metamorphism of a siliceous dolomitic limestone with the input of a variable amount of a potassic magma, possibly the same from which the t-A phlogopites formed, with the exception of one sample, for which a different parental magma is suggested. Indeed, there is an almost continuous spectrum of crystal-chemical and structural parameters starting from t-B and evolving towards t-A phlogopites. The t-A phlogopites displays complex, apparently meaningless relationships in their crystal-chemical parameters, thus indicating interplay of several substitution mechanisms. They possibly formed in polybaric conditions, since their cell volumes differ, but the total size of the cations hosted in the octahedral sheet is the same.

2009 - Heavy metals in sediments from canals for water supplying and drainage: mobilization and control strategies [Articolo su rivista]
Malferrari, Daniele; Brigatti, Maria Franca; Laurora, Angela; Pini, Stefano
abstract

One of the most critical aspects of the maintenance of canals forwater supplying and drainage is the managingof deposited sediments, which must be periodically removed. Deposited sediments, if containinganthropogenic pollutants with a concentration exceeding specific law limits, must be stored as industrialwastes, thus raising additional economic and logistic problems to deal with. Our research considers pollutedsediments from an area close to the south side of Po river, in order to characterize heavy metalsassociated with different mineral species, thus defining effective treatments for their inertization, andsuggesting a possible process for their recycle. Our results demonstrate that the composition of thesesediments is suitable for the production of tiles and bricks. Several testswere thus performed to optimizesample treatment and other process parameters, finally giving very encouraging results. Releasing testson fired products reveal that all the heavy metals are well retained.

2009 - Layer charge and heavy metals structures in hydrated 2 : 1 silicates:state of the art and new advances on cadmium [Articolo su rivista]
Malferrari, Daniele; Brigatti, Maria Franca; Elmi, Chiara; Laurora, Angela; G., Valdre
abstract

This study will discuss how layer charge can affect chemical speciation and topology of heavy metals adsorbed to 2:1 layer silicates, by providing: i) an overview of literature data; ii) experimental data on Cd complexes adsorbed by 2:1 layer silicates with different layer charge (montmorillonite and vermiculite); iii) a comparison between our results and literature data. This study will also be supported by several different experimental techniques such as chemical and thermal analyses, X-ray powder diffraction and X-ray absorption spectroscopy.Based on our data Cd atoms were found to complex water molecules in both clay minerals and to show four-fold coordination in montmorillonite (CdO distances of 2.24 Å) and six-fold coordination in vermiculite (CdO distances of 2.16 and 2.28 Å). Furthermore our models clearly suggest that Cd mainly bonds to interlayer water, without neglecting the more limited, but still significant, Cd multinuclear surface complexes at the octahedral broken edges. Both clay minerals show H2O/Cd ratio, as evidenced by thermal analyses, drastically higher than expected from X-ray adsorption spectroscopy data, thus implying that most of the water molecules are only loosely coordinated to interlayer cations.

2009 - Mobilization of heavy metals from fluvial sediments (Tiepido river, Modena, Italy): mineralogical and chemical investigation to prevent potential environmental hazard [Abstract in Rivista]
Malferrari, Daniele; Brigatti, Maria Franca; Laurora, Angela; Venturini, S.
abstract

2009 - Natural Reserves as a tool for the recovery and exploitation of abandoned mining areas: Hg in soils and sediments from Pigelleto (Piancastagnaio, Siena, Italy) Natural Reserve [Abstract in Rivista]
Malferrari, Daniele; Brigatti, Maria Franca; Laurora, Angela; Zanerini, L.
abstract

2009 - Nomenclature for stacking in phyllosilicates: report of the Association Internationale pour l'Etude des Argiles (AIPEA) nomenclature committee for 2008 [Articolo su rivista]
Guggenheim, S.; Adams, J. M.; Bergaya, F.; Brigatti, Maria Franca; Drits, V. A.; Formoso, M. L. L.; Galan, E.; Kogure, T.; Stanjek, H.; Stucki, J. W.
abstract

Two recommendations are made in regard to the nomenclature for stacking in, first 2:1 and then 1:1, phyllosilicates. The first recommendation is meant to eliminate ambiguity in use of the adjective 'interlayer' for 2:1 layer phyllosilicates. It is recommended that the layer displacement for 2:1 layers be defined as the sum of the intralayer displacement and the interlayer displacement. Intralayer displacement and interlayer displacement are discussed and exactly defined. The term 'structure unit' of Bailey (1980) is the total assemblage of the layer plus interlayer. For 1:1 layers the layer displacement can also be defined as the relative lateral displacement between adjacent layers. However, Bailey (1988) termed this displacement 'interlayer shift'. To avoid confusion and to maintain parallelism with 2:1 layers the term 'layer displacement' should be used, instead of 'interlayer shift'. The terms 'adjacent layer displacement' and 'layer shift' are equiv. to 'layer displacement'.

2009 - Nomenclature for stacking in phyllosilicates: report of the association internationale Pour L'etude Des Argiles (Aipea) nomenclature committee for 2008 [Articolo su rivista]
Guggenheim, S.; Adams, J. M.; Bergaya, F.; Brigatti, Maria Franca; Drits, V. A.; Formoso, M. L. L.; Galan, E.; Kogure, T.; Stanjek, H.; Stucki, J. W.
abstract

2009 - Octahedral cation ordering and magnetic behavior of micas [Abstract in Rivista]
Pini, S.; Affronte, Marco; Brigatti, Maria Franca; Malferrari, Daniele; Marcelli, A.
abstract

2009 - Osumilite from Mount Arci (Sardinia, Italy): bulk and surface crystal chemistry [Abstract in Rivista]
Elmi, Chiara; Brigatti, Maria Franca; Pasquali, Luca; Montecchi, Monica; Laurora, Angela; Malferrari, Daniele; Nannarone, Stefano
abstract

This study is focused on osumilite crystal chemistry and on its surface chemical characteristics and properties. Osumilite belongs to the milarite mineral group. This mineral, with the ideal formula XIICIXB’2VIA2(T2)3IV(T1)12O30 crystallizes in the space group P6/mcc. T1 is mainly occupied by Si and to a smaller amount by Al, T2 is usually occupied by Al with Fe and little Mg, whereas A octahedron mostly contains Mg and Fe. The ring arrangement defines structural channels occupied by the twelve-coordinated C site which is characterized by the presence of alkaline cations (Na, K).The osumilite from Mt Arci (Sardinia) occurs in thin fissures and small cavities within a rhyolite from the volcanic massif of Mt. Arci, Sardinia. The mineral forms regular dark blue hexagonal prismatic-tabular crystals associated to trydimite and sporadic phlogopite crystals. The osumilite structure was refined by single crystal X-ray diffraction and the final refinement yielded the following agreement factors R = 0.0199. The sample studied is hexagonal, with symmetry P6/mcc and unit cell parameters a = 10.1550(6) c = 14.306(1) (Å). The structural formula is (K0.729)C (Na0.029)B’ (Si10.498 Al1.502)T1 (Al2.706 Fe2+0.219 Mg0.075)T2 (Mg0.660 Mn0.091 Fe2+1.258)AO30. In respect of data from literature [2], osumilite sample from Mt. Arci is characterized by a significantly high Fe content (1.478 apfu).In order to study the morphology of osumilite from Mt. Arci, an atomic force microscopy (AFM) filtered images of osumilite was performed. The (001) surface roughness of osumilite is about 0.40 nm, thus it confirms the presence of the channels defined by the double rings of tetrahedra. The distance between two dark areas, defining channel position, is 1 nm, which well agree with the unit cell parameter a value.X-ray photoelectron spectroscopy (XPS) analysis was carried out to measure chemical composition and quantity of each element on the osumilite surface. Higher resolution spectra in the region of Si2p, Al2p, Mg1s and Fe2p core levels were measured. From data collected, we could say that the osumilite surface is chemically well characterized and the elemental composition of surface totally corresponds to the bulk chemical composition. Moreover, comparing our results to data from literature we obtained also crystal chemical information on Fe, Mg, Si and Al high resolution spectra, compared to the crystal chemical characteristics of the bulk.In order to confirm the valence of Fe and the position of this element in the A site, X-ray absorption spectroscopy (XAS) was also made in the L2,3 edge of iron comparing data from literature.

2009 - Relationship between bulk and surface structure of muscovite [Abstract in Rivista]
Elmi, Chiara; Brigatti, Maria Franca; Malferrari, Daniele; Castro, G. R.; Ferrer Escorihuela, P.; Rubio Zuazo, J.
abstract

The aim of this project is to study the relationships between bulk and surface structure of a natural muscovite crystal.The muscovite studied [(K0.92Na0.08) (Al1.86Fe3+0.01Mg.0.07 Fe2+0.06Ti0.02) (Si3.03Al0.97) O10 F0.09 (OH)1.91] is monoclinic, 2M1 polytype, with symmetry C2/c and unit cell parameters a = 5.19690(10) b = 9.0138(3) c = 20.0835(7) (Å) and β = 95.763(2) (°).The muscovite structure was refined by single crystal X-ray diffraction and the final refinement yielded the following agreement factor R = 0.0299. The difference Fourier map shows a significant residual electron density (2.2-) close to the position related to M1 site, thus indicating that the excess of octahedral cations is located at M1. M1-O mean bond distance is 2.247(9) and M2-O distance is 1.929.Grazing incidence X-ray diffraction (GIXRD) was recently performed at SpLine at ESRF. This type of analysis is very useful to identify typical structural features of the surface, such as possible imperfections, relaxations or reconstructions of the surface [1]. Preliminary data collected by GIXRD could indicate that on muscovite surface a reconstruction could occur, but we need more reflections to be certain of this assumption. Some indirect evidence of surface modification of mica crystals may be suggested by a lower K content on mica surface than observed in the bulk, which is a rather common observation when subjecting micas to chemical analyses. K release can also be attributed to a variation of interlayer cavity topology at surface, as well as to a breaking of K-O bonding. This effect can play a significant role in determining surface charge in micas, either completely negative, or partly positive and partly negative, depending on K release.

2008 - Clinochlore structure and its surface interactions with organic molecoles [Relazione in Atti di Convegno]
Elmi, Chiara; Brigatti, Maria Franca; Malferrari, Daniele; Valdrè, G.; Castro, G. R.; Rubio Zuazo, J.
abstract

This study is focused on clinochlore crystal chemistry and on its surface interactions with biomolecules. Clinochlore, which is a chlorite, is formed by two different polyhedral units: (i) two tetrahedral sheets (T) sandwiching a Mg-rich octahedral sheet (O) and (ii) an octahedral Mg-, Al-rich, brucite-like, interlayer (B). The excess of negative charge of the TOT layer is neutralized by the positively charged B interlayer. Extensive hydrogen bonding provides structural cohesion between the TOT layer and the B interlayer.The clinoclhore studied is triclinic IIb-4 polytype, with symmetry C and unit cell parameters a = 5.3301(4) b = 9.2511(6) c = 14.348(1) (Å) α = 90.42(1) β = 97.51(1) γ = 90.00(2) (°). The chemical composition is [VI](Mg9.6Fe2+0.27Al2.01Cr0.09)[IV](Si5.86Al2.14)O20(OH)16.Measurements of surface reflectivity carried out at ESRF, Spanish beam line, suggest that biological molecules, such as nucleotides, can be adsorbed as (001) organized layer on the mineral surface. Furthermore AFM (Atomic Force Microscopy) and EFM (Electric Force Microscopy) studies suggest that clinochlore presents at the nanoscale, negative regions of exposed oxygens (tetrahedral sheets, lower layer) and positive regions of exposed hydroxyl groups belonging to the brucite-like which is about 0.5 nm thick [1]: the brucite-like layer is more effective in assembling the biological molecules rather than the exposed oxygen surface.

2008 - Crystal chemical modeling and XANES spectroscopy of potassium micas [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Malferrari, Daniele; Mottana, A.; Cibin, G.; Marcelli, A.; Cinque, G.
abstract

2008 - DNA interactions with clinochlore surface [Relazione in Atti di Convegno]
Valdrè, G.; Brigatti, Maria Franca; Malferrari, Daniele
abstract

2008 - Effect of temperature on Hg- and Hg-cysteine complexes in vermiculite and montmorillonite interlayer [Relazione in Atti di Convegno]
Malferrari, Daniele; Brigatti, Maria Franca; Elmi, Chiara; Marcelli, A.; Chu, W.; Wu, Z.
abstract

Presentazione orale

2008 - I suoli a mirtillo (Appennino Modenese) [Relazione in Atti di Convegno]
P., Marchetto; Laurora, Angela; Malferrari, Daniele; Brigatti, Maria Franca; Bosi, Giovanna
abstract

Lo scopo dello studio è di verificare se la crescente diffusione di falso mirtillo nei vaccinieti spontanei del territorio del Frignanp (Alto Appennino modenese) sia correlata con la variazione delle caratteristiche chimico-ficsiche del suolo.

2008 - Interlayer potassium and its neighboring atoms in micas: Crystal chemical modeling and XANES spectroscopy [Articolo su rivista]
Brigatti, Maria Franca; Malferrari, Daniele; Poppi, M; Mottana, A; Cibin, G; Marcelli, A; Cinque, G.
abstract

The aim of this work is to provide a detailed description of the interlayer site in trioctahedral true micas by combining crystal-chemical and spectroscopic evidence. Insights obtained are based on a statistical appraisal of crystal-chemical, structural and spectroscopic data determined on two sets of trioctahedral micas extensively studied by both X-ray diffraction refinement on single crystals (SC-XRD) and X-ray absorption fine spectroscopy (XAFS) at the potassium K-edge. Spectroscopy was carried out on both random powders and oriented cleavage flakes, the latter setting taking advantage of the polarized character of synchrotron radiation. Such an approach (AXANES) is shown to be complementary to crystal-chemical investigation based on SC-XRD refinement. However, the results are not definitive as they focus on few samples having extreme features only (e.g., end-members, unusual compositions, and samples with extreme and well-identified substitution mechanisms). The experimental absorption K-edge (XANES) was decomposed by calculation and extrapolated into a full in-plane absorption component and a full out-of-plane absorption component. These two patterns reflect different structural features: represents the arrangement of the atoms located in the mica interlayer space and facing tetrahedral sheets; is associated to multiple-scattering interactions entering deep into the mica structure, thus reflecting also interactions with the heavy atoms (essentially Fe) located in the octahedral sheet. The out-of-plane patterns also reflect somewhat the octahedral atoms electronic properties, such as their oxidation states (e.g., Fe2+ and Fe3+) and their ordering (e.g., trans- vs. cis-setting). Distinction between fluoro- and hydrous micas is also possible due to peculiar absorption features originating from the F vs. OH occupancy of the O4 octahedral site. Thus, combining structural and spectroscopic information is shown to be a practical method that allows, on one hand, assigning the observed spectroscopic features to precise structural pathways followed by the photoelectron within the mica structure and, on the other hand, clarifying on the amount of electronic interactions and forces acting onto the individual atoms at the various structural sites.

2008 - Kelvin probe and surface shear microscopy of layer silicates [Relazione in Atti di Convegno]
Valdrè, G.; Moro, D.; Malferrari, Daniele; Brigatti, Maria Franca
abstract

2008 - Magnetic behaviour of trioctahedral mica-2M1 occurring in amagnetic anomaly zone [Articolo su rivista]
Pini, Stefano; Affronte, Marco; Brigatti, Maria Franca
abstract

This work relates the crystal chemistry and the magnetic behaviour of a trioctahedral mica (chemical formula: K0.90Na0.01Ca0.01Ba0.01&0.07)(Al0.05Fe2+ 1.20Mg1.38Ti0.32Mn0.01&0.04)(Al1.12Si2.88)O10 (F0.27OH1.27O0.46); unit cell parameters: a = 5.345(2), b = 9.261(4), c = 20.189(8) A; b =95.075(8)º) from Minto Block (Ungava peninsula, northern Quebec, Canada), a region characterized by high magnetic anomalies. Crystallographic and X-ray absorption spectroscopy data suggest a prevalentdivalent oxidation state for Fe and a disordered Fe2+ distribution in the two octahedralsites M1 and M2. The realpart of magnetic susceptibility shows two peaks at ~5.2 K and 120 K. However, asdemonstrated by AC magnetic susceptibility measurements, the origin of the two effects is different: the peak position of the first one (i.e. the effect revealed at 5.2 K) is frequency-dependent, thus suggesting a spin-glass like behaviour. The effect at 120 K can instead be attributed to the occurrence of diluted phases in mica matrix, such as Fe oxides.

2008 - Modification of Hg complexes in layered silicates with temperature: an in situ XAS study [Articolo su rivista]
Malferrari, Daniele; Brigatti, Maria Franca; Marcelli, A; Chu, W; Wu, Z.
abstract

This work will address the thermal evolution (variation in oxidation state, disproportionation reactions) of Hg(II), adsorbed by two different layer silicates (montmorillonite and vermiculite) via XAS spectroscopy at increasing temperature. From the XANES analysis we could recognize significant structural differences between Hg-treated montmorillonite and vermiculite even at room temperature. At increasing temperature Hg is not easily removed from the silicate layer and it could be identified in layer structure up to T = 400 °C in montmorillonite and up to T = 700 °C in vermiculite. Furthermore, it is evident from EXAFS spectra collected at room temperature that Hg–H2O complexes are present in both montmorillonite and vermiculite, whereas the HgO form appears only in vermiculite.

2008 - Single-crystal X-ray studies of trioctahedral micas coexisting with dioctahedral micas in metamorphic sequences from Western Maine [Articolo su rivista]
Brigatti, Maria Franca; Guidotti, Cv; Malferrari, Daniele; Sassi, Fp
abstract

A crystal chemical study of thirteen biotite (twelve of 1M polytype and one of 2M1 polytype) and four muscovite samples were made. The biotite, coexists with the muscovite. Samples are from metamorphic terrains and from granitic and granodioritic bodies occurring in three areas of western Maine. The metamorphic mineral zones identified by mineral compatibilities are, for increasing metamorphic grade, the Lower Sillimanite Zone (LSZ), the Upper Sillimanite Zone (USZ) and the K-feldspar + Sillimanite Zone (K+SZ). The muscovite composition clusters near ideal muscovite and displays a small celadonite substitution and a small, but variable paragonite substitution. The biotite composition displays a ratio [vi]Mg2+ / [vi](Mg2+ + Fe2+) ranging from 0.26 to 0.54 and significant octahedral Al content from 0.48 to 0.72 apfu in metamorphic biotite samples and from 0.51 to 0.67 in those from granites).In trioctahedral micas from western Maine and especially in those with graphite, there is a greater number of interlayer vacancies than in common micas. Interlayer vacancies have an increase in interlayer cation – basal oxygen atom distances and a decrease in tetrahedral flattening angle tau, thus suggesting a reduced interlayer charge. With a few exceptions, tetrahedral rotation angle alpha is related to crystallization temperature. In particular alpha decreases with a temperature increase, and alpha is also related to octahedral chemical substitutions. Results tentatively suggest, for micas from metamorphic environments, a direct influence of genetic parameters (T and fO2) on mica crystal structure, and not just chemical composition.

2008 - The octahedral anionic site in micas: a comparison between fluorannite and annite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Caprilli, Enrico; Malferrari, Daniele; Mottana, A.
abstract

2008 - X-ray microdiffraction as a tool for single crystal structure refinement: a study on apatite crystals [Relazione in Atti di Convegno]
Medici, L.; Brigatti, Maria Franca; Malferrari, Daniele
abstract

Poster

2007 - CRYSTAL STRUCTURE AND CHEMISTRY OF PHYLLOSILICATES: SOME RECENT PERSPECTIVES AND NEW TRENDS [Relazione in Atti di Convegno]
Brigatti, Maria Franca
abstract

The study of phyllosilicates, in particular the microcrystalline species that constitute clay minerals, was widely addressed in recent literature (for a review, BERGAYA et al., 2006). Many works related to layer silicates are not only published on dedicated journals, such as Clay Minerals, Clays and Clay Minerals and Applied Clay Sciences but also on numerous magazines oriented toward Mineralogy, Petrology, Geochemistry, Applied Chemistry, Environmental Sciences, Food and Soil Science, Ceramics, Applied Physics, Enginery, Water Science and Biology. During the beginning of 2007 (from January to April) more than 1200 contributions were published on clay minerals, also including 340 patents. Among these works, many address, or recall, the structure and crystal chemistry of clay minerals to account for different features and properties, also depending from chemical and physical experimental or environmental conditions. The great attention and relevance devoted to the crystal chemistry and structure of clay minerals are counterbalanced by a remarkable experimental complexity, characterizing most aspects in this field of research, thus also accounting for a significant lack of chemical homogeneity in the information available.In particular single crystal approaches on clay minerals are limited, in our current technological frameset, not only by the microcrystalline dimensions, common for clay minerals particles, and by their association with other phases, but also by their hydration, lack of homogeneity from layer to layer and stacking faults. A further complexity is also associated to the interlamination of different phyllosilicates. During last decades, transmission electron microscopy, X-ray powder diffraction techniques, spectroscopic techniques and theoretical or modeling approaches allowed a rather accurate description of the stacking sequence, at least when the basal spacing for the constituting layers is significantly different. Many recent contributions addressed interlaminated phases where this latter constraint is not fulfilled, both via experiment and theoretical approaches. A first example is constituted by the stacking of trans-vacant and cis-vacant illite layers, where DRITS et al. (1998, 2006) suggested a simple identification criterion based on the presence of d110 reflection violating the individual layer symmetry. A second example is constituted by 7Å serpentine and 14Å chlorite (e.g., ŚRODOŃ, 1999; XU & VEBLEN, 1996; BANFIELD & BAILEY, 1996). Moreover significant question marks still apply for the detailed crystallographic and crystal chemical description of the constituting layer, especially for what concerns cation exchange, the formation of high temperature phases and the establishment of different interlayer complexes. The relevance of all the above mentioned fields of investigation is not only speculative, but also deeply applicative.This brief introduction clearly depicts a frameset where an inherent complexity is well evident for most of the crystal chemical and crystallographic investigations on clay minerals, together with their remarkable speculative and applicative impact. A complete description is outside the scope and time-constraint of this document, where some examples and hot-spots will be addressed, together with some, nowadays substantially obscure aspects, that technical progress may render viable for investigation in the near future. In more detail the points that will be addressed are listed below:1.An historic background and recent advances on the structural description of a well characterized clay mineral: kaolinite.2.Crystal chemistry and structure of dioctahedral and trioctahedral micas: some recent advances and implication on clay structure. 3.Layer charge location and interlayer complexes.

2007 - Crystal chemical modeling and XANES spectroscopy of K in interlayer site of micas [Abstract in Rivista]
Malferrari, Daniele; Brigatti, Maria Franca; Poppi, Marco; Mottana, A.; Cibin, G.; Marcelli, A.; Cinque, G.
abstract

A detailed description of the interlayer site in trioctahedral true micas is presented based on a statistical appraisal of crystal-chemical, structural, and spectroscopic data determined on two sets of trioctahedral micas extensively studied by both X-ray diffraction refinement on single crystals (SC-XRD) and X-ray absorption fine spectroscopy (XAFS) at the potassium K-edge. Spectroscopy was carried out on both random powders and oriented cleavage flakes, the latter setting taking advantage of the polarized character of synchrotron radiation. Such an approach (AXANES) is shown to be complementary to crystal-chemical investigation based on SC-XRD refinement. However, the results are not definitive as they focus on few samples having extreme features only (e.g., end-members, unusual compositions, and samples with extreme and well-identified substitution mechanisms). The experimental absorption K-edge (XANES) for potassium was decomposed by calculation and extrapolated into a full in-plane absorption component (sigma (sub ) ) and a full out-of-plane absorption component (sigma ). These two patterns reflect different structural features: sigma (sub ) represents the arrangement of the atoms located in the mica interlayer space and facing tetrahedral sheets; sigma is associated with multiple-scattering interactions entering deep into the mica structure, thus also reflecting interactions with the heavy atoms (essentially Fe) located in the octahedral sheet. The out-of-plane patterns also provide insights into the electronic properties of the octahedral cations, such as their oxidation states (e.g., Fe (super 2+) and Fe (super 3+) ) and their ordering (e.g., trans- vs. cis-setting). It is also possible to distinguish between F- and OH-rich micas due to peculiar absorption features originating from the F vs. OH occupancy of the O4 octahedral site. Thus, combining crystal-chemical, structural, and spectroscopic information is shown to be a practical method that allows, on one hand, assignment of the observed spectroscopic features to precise structural pathways followed by the photoelectron within the mica structure and, on the other hand, clarification of the amount of electronic interactions and forces acting onto the individual atoms at the various structural sites.

2007 - Crystal chemical modeling and XANES spectroscopy of the potassium interlayer in micas [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Malferrari, Daniele; Poppi, M.; Mottana, A.; Cibin, G.; Marcelli, A.; Cinque, G.
abstract

2007 - Crystal chemistry and structure of Lizardite-1T in serpentinite rocks from the Northern Apennine ophiolites (Modena Province). [Abstract in Rivista]
Laurora, Angela; Brigatti, Maria Franca; Ferrari, M.; Galli, Ermanno; Rossi, Antonio
abstract

2007 - Crystal chemistry of chlinoclore for biochemical assays [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Valdré, G.
abstract

2007 - Crystal chemistry of trioctahedral micas in alkaline and subalkaline volcanic rocks: A case study from Mt. Sassetto (Tolfa district, Latium, central Italy) [Articolo su rivista]
Laurora, Angela; Brigatti, Maria Franca; Mottana, A.; Malferrari, Daniele; Caprilli, Enrico
abstract

This work provides a crystal-chemical description of trioctahedral micas from volcanic rocks (lavas, tuffs, ignimbrites, and xenoliths) outcropping at Mt. Sassetto (Tolfa district, Tuscan Province, central Italy). Mica crystals vary in composition from ferroan phlogopite to magnesian annite. Heterovalent octahedral substitutions are mainly related to Al3+, Ti4+, and, only in a few samples, to Fe3+. The two main mechanisms regulating Ti inlet into the mica structure are the Ti-oxy [Ti-VI(4+VI)(Mg,Fe)(-1)(2+)(OH)(-2)O--(2)2-] and Ti-vacancy [Ti-VI(4+VI)rectangle(VI)(Mg,Fe)(-2)(2+)] substitutions. In these micas, Ti content is the predominant crystal-chemical parameter and significantly affects octahedral and interlayer topology as well. Micas with the highest Ti contents deviate from the expected fractional crystallization trend in the Ti vs. Mg/(Mg + Fe-tot) diagram, possibly as a consequence of a variation in intensive parameters (T, P, f(H2),f(O2),f(H2O)) during crystallization in the magmatic chamber. In micas with significant Fe3+ contents, the layer charge balance is accomplished by the following mechanisms: (Fe-32+VIFe23+VI)-Fe-VI rectangle, (Fe-12+VIFe3+)-Fe-VI(OH)(-)O--(2-), and (Fe-12+VIFe3+IVSi-14+IVAl3+)-Fe-Vi. These micas show mean electron counts greater for the octahedral M2 site than for M1, and unit-cell parameters significantly smaller than usual for other micas. Atmospheric weathering is unlikely to produce the observed Fe oxidation. The Fe3+-vacancy and Fe-oxy substitutions could represent secondary, re-equilibration effects related to post-eruptive water-rock hydrothermal processes (acid-sulfate alteration).

2007 - Crystal structure and chemical composition of Li-, Fe-, and Mn-rich micas [Articolo su rivista]
Brigatti, Maria Franca; Mottana, A; Malferrari, Daniele; Cibin, G.
abstract

We present in this paper the crystal chemical characterization of three (Fe, Mn)-rich lithian trioctahedral micas. The samples are from Hirukawa mine (Japan) (unit formula: [iv](Si3.425Al0.575)4.00[vi](Al1.002Ti0.002Cr0.001Fe0.379Mg0.005Mn0.173Li1.438)3.00 [xii](Ca0.002Ba0.001Na0.049K0.948Rb0.002)1.00 O10F2 ; unit-cell dimensions: a = 5.264(1), b = 9.086(2), c = 10.099(3) Å, β = 100.719(5)°, V = 474.6(2) Å3); from Mokrusha mine (Russia) (unit formula: [iv](Si3.304Al0.696)4.00 [vi](Al1.004Ti0.001Fe0.362Mg0.005 Mn0.306Li1.322)3.00 [xii](Ca0.012Ba0.001Na0.042K0.940Rb0.005)1.00 O10F2; unit-cell dimensions: a = 5.297(5), b = 9.133(7), c = 10.168(9) Å, β = 100.78(2)°, V = 483.2(7) Å3); and from Sawtooth Mountains (Boise County, Idaho, U.S.A.) (unit formula: [iv](Si3.105Al0.895)4.00 [vi](Al0.913Ti0.018 Fe0.456Mg0.031 Mn0.521Li1.061)3.00 [xii](Ca0.004Ba0.003Na0.048K0.924Rb0.021)1.00 O10F2; unit-cell dimensions a = 5.2984(3), b = 9.1461(6), c = 10.0966(7) Å, β = 100.818(4)°, V = 480.58(5) Å3). All crystals belong to 1M polytype with layer symmetry C12(1) and show M1 and M3 sites much greater than M2. Moreover mean electron count values are much more variable for M1 and M3 sites than for M2. Unlike sample from Sawtooth Mountains, tetrahedral mean bond lengths appear to be smaller for T1 than for T11 site in Hirukawa mine and in Mokrusha mine.When compared to samples from the zinnwaldite series, crystals under study show similar crystal chemical trends, thus hinting to similar effects produced on layer structure by Fe and Mn cations.

2007 - Crystal structure and crystal chemistry of fluorannite and its relationships to annite [Articolo su rivista]
Brigatti, Maria Franca; Caprilli, Enrico; Malferrari, Daniele; Mottana, A.
abstract

This contribution deals about the crystal chemical characterization of fluorannite from Katugin Ta-Nb deposit, Chitinskaya Oblast’, Kalar Range, Transbaikalia, Eastern-Siberian Region, Russia. The mineral chemical formula is (K0.960Na0.020Ba0.001) (Fe2+2.102Fe3+0.425Cr3+0.002Mg0.039Li0.085Ti0.210Mn0.057) (Al0.674 Si3.326) O10 (F1.060OH0.028O0.912). This mica belongs to 1M polytype (space group C2/m) with layer parameters a = 5.3454(2) Å, b = 9.2607(4) Å, c = 10.2040(5) Å, beta = 100.169(3)°. Structure refinement, using anisotropic displacement parameters, converged at R = 0.0384. When compared to annite, fluorannite shows a smaller cell volume (Vfluorannite = 497.19 Å3; Vannite = 505.71 Å3), because of its smaller lateral dimensions and its reduced c parameter. The flattening of the tetrahedral basal oxygen atoms plane decreases with F content, together with the A-O4 distance (i.e., the distance between interlayer A cation and the octahedral anionic position) because of the reduced repulsion between the interlayer cation and the anion sited in O4.

2007 - Effect of iron ordering on magnetic properties of 2:1 layer silicates [Relazione in Atti di Convegno]
Pini, Stefano; Brigatti, Maria Franca; Di Gioacchino, D.; Marcelli, A.; Tripodi, P.
abstract

2007 - Erratum: Summary of recommendations of nomenclature committees relevant to clay mineralogy: Report of the Association International pour l'Etude des Argiles (AIPEA) Nomenclature Committee for 2006 (Clays and Clay Minerals) [Articolo su rivista]
Guggenheim, S; Adams, Jm; Bain, D. C.; Bergaya, F; Brigatti, Maria Franca; Drits, Va; Formoso, Mll; Galan, E; Kogure, T; Stanjek, H.
abstract

ecently Kogure and co-workers published several papers reporting the stacking structures of various 2:1 layer phyllosilicates (e.g., aspidolite, Kogure et al., 2004; wonesite, Kogure et al., 2005; pyrophyllite, Kogure et al., 2006), mainly by using high-resolution TEM. However, there is ambiguity in wording that refers to the lateral displacement between two tetrahedral sheets across the interlayer regions. Zvyagin et al. (1969) used the symbol "" for this displacement, which describes the structures of pyrophyllite and talc, but no universally accepted wording was used for other 2:1 phyllosilicates or 1:1 phyllosilicates. Bailey (1984, p. 32) referred to the "layer offset" for this displacement in mica, but the original meaning of “layer offset” can be taken as the "displacement" to offset the intralayer shift of the 2:1 layer. A more precise meaning of these terms is needed that can be applied to not only the micas, but other 2:1 layer phyllosilicates also. Recommendations are also included for 1:1 layers.

2007 - Erratum: Summary of recommendations of nomenclature committees relevant to clay mineralogy: Report of the Association International pour l'etude des argiles (AIPEA) nomenclature committee for 2006 (Clay Minerals (2007) vol 42) [Articolo su rivista]
Guggenheim, S; Adams J., M; Bain, Dc; Bergaya, F; Brigatti, Maria Franca; Drits V., A; Formoso, Mll; Galan, E; Kogure, T; Stanjek, H.
abstract

Recently Kogure and co-workers published several papers reporting the stacking structures of various 2:1 layer phyllosilicates (e.g., aspidolite, Kogure et al., 2004; wonesite, Kogure et al., 2005; pyrophyllite, Kogure et al., 2006), mainly by using high-resolution TEM. However, there is ambiguity in wording that refers to the lateral displacement between two tetrahedral sheets across the interlayer regions. Zvyagin et al. (1969) used the symbol "" for this displacement, which describes the structures of pyrophyllite and talc, but no universally accepted wording was used for other 2:1 phyllosilicates or 1:1 phyllosilicates. Bailey (1984, p. 32) referred to the "layer offset" for this displacement in mica, but the original meaning of “layer offset” can be taken as the "displacement" to offset the intralayer shift of the 2:1 layer. A more precise meaning of these terms is needed that can be applied to not only the micas, but other 2:1 layer phyllosilicates also. Recommendations are also included for 1:1 layers.

2007 - Il mirtillo nero del Frignano: risorsa da conoscere, valorizzare e difendere [Altro]
Brigatti, Maria Franca; Malferrari, Daniele
abstract

Convegno tenutosi a Pavullo nel Frignano (Modena, Italy) il 25 maggio 2007.

2007 - Influence of magnetic properties of iron coordination and ordering in micas [Abstract in Rivista]
Pini, S.; Brigatti, Maria Franca; Di Gioacchino, D.; Marcelli, A.; Tripodi, P.
abstract

2007 - Interlayer potassium and its surrounding in micas: Crystal chemical modeling and XANES spectroscopy [Abstract in Rivista]
Brigatti, Maria Franca; Malferrari, Daniele; Poppi, M.; Mottana, A.; Cibin, G.; Marcelli, A.; Cinque, G.
abstract

Crystal chemistry and topology of the interlayer cations in micas were detailed by several authors and readily appeared not only to be sensitive to the interlayer composition, but to mirror also the topology of other sites occurring in the mica structure (i.e., tetrahedral, octahedral and anionic sites). The aim of this work is to provide a detailed description of the interlayer site in trioctahedral true micas by combining crystal-chemical and spectroscopic evidence. Insights obtained are based on a statistical appraisal of crystal-chemical, structural and spectroscopic data determined on two sets of trioctahedral micas extensively studied by both X-ray diffraction refinement on single crystals (SC-XRD) and X-ray absorption fine spectroscopy (XAFS) at the potassium K-edge. Spectroscopy was carried out on both random powders and oriented cleavage flakes, the latter setting taking advantage of the polarized character of synchrotron radiation. Such an approach (AXANES) is shown to be complementary to crystal-chemical investigation based on SC-XRD refinement. However, the results are not definitive as they focus on few samples having extreme features only (e.g., end-members, unusual compositions, and samples with extreme and well identified substitution mechanisms). The experimental absorption K-edge (XANES) was decomposed by calculation and extrapolated into a full in-plane absorption component (||) and a full out-of-plane absorption component (?). These two patterns reflect different structural features: || represents the arrangement of the atoms located in the mica interlayer space and facing tetrahedral sheets; ? is associated to multiplescattering interactions entering deep into the mica structure, thus reflecting also interactions with the heavy atoms (essentially Fe) located in the octahedral sheet. The out-of-plane pattern also reflects somewhat the octahedral atoms electronic properties, such as their oxidation states (e.g., Fe2+ and Fe3+) and their ordering (e.g., trans- vs. cis-setting). Distinction between fluoro- and hydrous micas is also possible due to peculiar absorption features originating from the F vs. OH occupancy of the O4 octahedral site. Thus, combining structural and spectroscopic information is shown to be a practical method that allows, on one hand, assigning the observed spectroscopic features to precise structural pathways followed by the photoelectron within the mica structure and, on the other hand, clarifying on the amount of electronic interactions and forces acting onto the individual atoms at the various structural sites.

2007 - Lizardite-1T in serpentinite rocks from the Northern Apennine ophiolites (Province of Modena, Italy) [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Ferrari, M.; Galli, Ermanno; Laurora, Angela; Rossi, Antonio
abstract

2007 - Magnetism of micas: a comparison between crustal chemistry and AC susceptibility [Abstract in Rivista]
Pini, S.; Brigatti, Maria Franca; Di Gioacchino, D.; Marcelli, A.; Tripodi, P.
abstract

Although silicate minerals are the principal constituents of Earth’s crust and mantle and iron is the most widespread magnetic element, few reliable studies on magnetic properties of iron-silicates were performed on natural samples, chemically and structurally well characterized. This work will address layer silicates magnetic properties, with special focus on micas, which, from a magnetic viewpoint, can be classified as bidimensional systems.Iron in micas can be present as Fe2+ and Fe3+ and thus different magnetic properties can arise from their 3d6 and 3d5 electronic configuration. Furthermore, differences in magnetic properties can be related to coordination. In fact Fe3+can substitute Si4+ in tetrahedral coordination in the phlogopite – tetra-ferriphlogopite join whereas Fe2+can substitute Mg2+ in octahedral coordination in the tetra-ferriphlogopite – tetra-ferri-annite join.Moreover, to preserve layer charge neutrality, other different mechanism can be introduced to compensate, for example, Fe3+ octahedral content.In this work, we considered four natural mica samples, two belonging to the phlogopite – annite join (Tag15-4 e C6b), one to the tetra-ferriphlogopite – tetra-ferri-annite join and one to the polylithionite – siderophyllite join.Crystal-chemical data suggest differences in the amount of Fe2+ in octahedral coordination between samples Tag15-4 and C6b ([6]Fe2+ 15 e 50% respectively).Tetra-ferriphlogopite Tas22-1 is characterized by Fe3+ tetrahedral substitution and by small Fe2+ and Fe3+content in octahedral position. Sample 103 shows Fe2+ and Fe3+in octahedral position.The susceptibility-temperature curves, related to AC magnetic measurements in thetemperature range 77-298 K, suggest an antiferromagnetic behaviour for Tag15-4,C6b and Tas22-1, whereas the susceptibility-temperature of sample 103 is completelydifferent.The different behaviour of sample 103 can be related to structural disorder that prevents Fe atoms alignment in octahedral sites.Moreover the magnetic magnitude is similar for C6b and Tag15-4 but differs substantially in Tas22-1, probably because of iron oxidation state and occupancy in the layer structure: mainly Fe2+ in octahedral sites for C6b and Tag15-4 and Fe3+ in tetrahedral sites for Tas22-1.

2007 - Polluted sediments from canals for water supplying and drainege: treatment and recycle [Abstract in Rivista]
Malferrari, Daniele; Brigatti, Maria Franca; Laurora, Angela; Pini, Stefano; Pistoni, Roberto
abstract

One of the most critical aspects of the maintenance of canals for water supplying and drainage is the managing of deposited sediments, which must be periodically removed. Deposited sediments, if containing anthropogenic pollutants with a concentration exceeding specific law limits, must be stored as industrial wastes, thus raising additional economic and logistic problems to deal with. Our research considers polluted sediments from an area close to the south side of Po river, in order to characterize heavy metals associated with different mineral species, thus defining effective treatments for their inertization, and suggesting a possible process for their recycle. Our results demonstrate that the composition of these sediments is suitable for the production of tiles and bricks. Several tests were thus performed to optimize sample treatment and other process parameters, finally giving very encouraging results. Releasing tests on fired products reveal that all the heavy metals are well retained.

2007 - Pollution of recent sediments from canals for water supplying and drainage [Relazione in Atti di Convegno]
Malferrari, Daniele; Brigatti, Maria Franca; Laurora, Angela; Pini, Stefano; Pistoni, Roberto
abstract

2007 - Recupero e valorizzazione di sedimenti estratti da canali di bonifica ed approvvigionamento idrico mediante inertizzazione termica. [Relazione in Atti di Convegno]
Pistoni, Roberto; Malferrari, Daniele; Brigatti, Maria Franca; Pini, Stefano; Tonelli, F.
abstract

2007 - Sedimenti provenienti dai canali di bonifica: valutazione del potenziale impatto ambientale. [Relazione in Atti di Convegno]
Malferrari, Daniele; Borghi, V.; Brigatti, Maria Franca; Laurora, Angela; Mantovani, E.; Pistoni, Roberto
abstract

2007 - Sorption kinetics and chemical forms of Cd(II) sorbed by thiol-functionalized 2:1 clay minerals [Articolo su rivista]
Malferrari, Daniele; Brigatti, Maria Franca; Laurora, Angela; Pini, Stefano; Medici, L.
abstract

The interaction between Cd(II) in aqueous solution and two 2:1 expandable clay minerals (i,e., montmorillonite and vermiculite), showing different layer charge, was addressed via batch sorption experiments on powdered clay minerals both untreated and amino-acid (cysteine) treated. Reaction products were characterized via X-ray diffraction, chemical analysis (Elemental Analysis and Atomic Absorption Spectrophotometry), thermal analysis, mass spectrometry and synchrotron-based X-ray absorption spectroscopy (XAS) techniques. Namely, the uptake of Cd(II) from each adsorbent was measured by analyzing, via atomic absorption spectroscopy, the liquid portion separated after centrifugation following a controlled period of exposure. The main outcome was thus the definition of the sorption behavior of Cd(II) as a function of the features of the substrates (e.g. different layer charge, presence or not of the amino acid cysteine). Thermal decomposition of Cd-cysteine treated clay minerals evidences the evolution of H2O, H2S, NO2, SO2, and N2O3. EXAFS studies suggest that Cd(II) coordinates with oxygen atoms, to give monomer complexes or CdO molecules, either on the mineral surface and/or in the interlayer. For Cd-cysteine complexes XAS data agree with the existence of Cd-S clusters, thus suggesting a predominant role of the thiol group in the bonding of Cd with the amino acid.

2007 - The effect of different plasma gas environments on vermiculite layer [Articolo su rivista]
Valdre, G; Malferrari, Daniele; Marchetti, Diego; Brigatti, Maria Franca
abstract

This work presents the first results of a broader research project aimed at the development or modifications of clays with increased properties for technological purposes and novel applications. This first step addresses on the chemical and physical properties of vermiculite treated with several ionised gasses in controlled plasma environments. Vermiculite is a 2:1 layered silicate with well-known chemical-exchange and surface properties useful in many industrial applications. The improving of these properties, in particular at the nanoscale level, can in principle enhance its application in known technological fields and extend its use in novel research and applicative areas as well as in nanotechnology. Vermiculite was treated with argon, air, water vapour and hydrogen radio frequency plasmas at room temperature for few minutes. As a general rule, plasma gasses induced various layer modifications. Chemical analyses evidenced a significant decrease in the interlayer cation content, especially for hydrogen and water vapour treated specimens. X-ray diffraction showed both a decrease of peak intensity and a halving of (001) reflection, thus suggesting the formation of layer defects along the layer stacking direction and onto (001) planes as well. Thermal analysis showed modifications of the temperature-activated reactions induced by the plasma treatments. Finally Fourier Transformed Infra-Red spectroscopy (FTIR) showed that different bonding of H2O occurred after the treatment, in particular for vermiculite treated with hydrogen plasma. (c) 2006 Elsevier B.V. All rights reserved.

2007 - Valutazione dello stato ambientale delle ex aree minerarie a solfuri di Boccassuolo (Palagano, Modena) e Cà Marsilio e Cà Gabriele (Montecreto, Modena) [Articolo su rivista]
Brigatti, Maria Franca; Galli, Ermanno; Malferrari, Daniele; Rossi, Antonio
abstract

Negli ultimi decenni l'ambiente ipogeo artificiale ha attirato l'attenzione di numerosi speleologi e di studiosi che, attraverso ricerche a carattere multidisciplinare, hanno evidenziato non solo il particolare significato storico, religioso e culturale di tali siti, ma anche la loro importanza quali strutture attraverso le quali, ad esempio, è awenuto il rifornimento idrico di grandi città e come opere realizzate dall'uomo anche in tempi recenti per coltivare giacimenti di materie prime utili alla sua quotidianità. In quest'ultimo caso si tratta delle numerose gallerie di miniera quasi tutte ormai abbandonate, ma che in parte, se almeno recuperate e rese sicure ed agibili, possono rappresentare una non trascurabile attrazione turistica e locale fonte di lavoro. Per alcune di queste realtà talora è sorta la preoccupazione della possibilità che le acque da esse derivate o le loroaree di discarica esterne rappresentassero agenti di potenziali inquinanti di territori (ambienti) circostantida parte di elementi tossici (pericolosi) presenti nelle mineralizzazioni coltivate.In relazione a questo problema, in questa nota vengono presentati i risultati di analisi relative adalcuni possibili agenti inquinanti naturali, effettuate su campioni di terreni e vegetali, raccolti nell'intornodelle due uniche zone minerarie a solfuri della provincia di Modena. In particolare è statavalutata la concentrazione di metalli pesanti (Cu, Zn e Pb) in sedimenti e licheni campionati nell'areacircostante il complesso minerario. È stata inoltre valutata la speciazione chimica di questi elementi combinando differenti tecniche analitiche. I risultati ottenuti indicano che l'inquinamentodella zona non raggiunge valori significativamente pericolosi e che gli attuali livelli sono comparabilia quelli determinati dalla stessa presenza del complesso minerario (inquinamento naturale)

2006 - Angular dependence of potassium K-edge XANES spectra of trioctahedral micas: Significance for the determination of the local structure and electronic behavior of the interlayer site [Articolo su rivista]
G., Cibin; A., Mottana; A., Marcelli; Brigatti, Maria Franca
abstract

The X-ray absorption angle-dependent behavior at the potassium K-edge has been determined for two end-members and two intermediate trioctahedral micas, which are representative of the Fe2+Mg-1, Fe3+Al-1, SiAl-1FeLi-1, and F-1OH exchange vectors, using horizontally polarized synchrotron radiation. Experimental spectra are interpreted by the multiple scattering theory following decomposition according to the angular dependence approach of Brouder (1990). The experimental spectra sum up anisotropic effects deriving from in-plane and out-of-plane photoelectron interactions with the potassium near- and next-near neighbors up to the fifth/sixth coordination sphere. For the first time, the absorption edge of a low Z atom is decomposed so as to produce two partial patterns giving, respectively, the full in-plane absorption spectrum (sigma(parallel to)) and the full out-of-plane spectrum (sigma(perpendicular to)). They fully describe the complete X-ray absorption dichroic behavior of layered compounds, of which mica is a prototype. sigma(parallel to) essentially reflects the arrangement of the atoms located in the mica interlayer space and facing tetrahedral sheets. Differences among the four micas depend on structural changes induced by the adaptation of their tetrahedral sheets to the increasing sizes of their octahedral sheet due to chemical substitutions (i.e., the Fe2+Mg-1 vector, mainly) and to chemical changes at the octahedral anion site (F-1OH vector). By contrast, sigma(perpendicular to) reflects multiple-scattering interactions entering deep into the mica structure, beyond the tetrahedral sheet and well into the octahedral sheet. Such contributions reflect both changes in the anions coordinating the octahedral cations and increasing total amount of heavy atoms (essentially Fe), and differ based on electronic properties such as oxidation states (e.g., Fe2+ and Fe3+). Therefore, angle-dependent XANES spectroscopy is one of the rare spectroscopic techniques able not only to detect, but also to quantify structural effects in the atoms at the medium-to long-range order.

2006 - Chapter 2 Structures and Mineralogy of Clay Minerals [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Galan, E; Theng, Bkg
abstract

Phyllosilicates considered in this section ideally contain a continuous tetrahedral sheet. Each tetrahedron consists of a cation, T, coordinated to 4 oxygen atoms, and linked to adjacent tetrahedra by sharing three corners (the basal oxygen atoms, Ob) to form an infinite two-dimensional “hexagonal” mesh pattern along the a, b crystallographic directions. In the octahedral sheet, connections between each octahedron, M, to neighbouring octahedra are made by sharing edges. Edge-shared octahedra form sheets of hexagonal or pseudo-hexagonal symmetry. Common tetrahedral cations are Si4+, Al3+, and Fe3+. Octahedral cations are usually Al3+, Fe3+, Mg2+, Fe2+, but other cations, such as Li+, Ti4+, Cr3+, Ni2+, Mn2+, Cu2+, V5+, Co2+, and Zn2+ have been identified. Octahedra show two different topologies related to (OH) position, i.e. the cis- and the trans-orientation. The free corners (the tetrahedral apical oxygen atoms, Oa) of all tetrahedra points to the same side of the sheet and connect tetrahedral and octahedral sheets to form a common plane with octahedral anionic position (note that OH can be commonly substituted by O, F and Cl). One octahedral sheet is linked to either one or two tetrahedral sheets. The 1:1 layer structure consists of one tetrahedral and one octahedral sheet, while in the 2:1 layer structure one octahedral sheet is sandwiched between two tetrahedral sheets. In the 1:1 layer structure, the unit cell contains 6 octahedral sites with 4 cis- and 2 trans-oriented octahedra, and 4 tetrahedral sites, whereas 6 octahedral sites (usually 4 cis- and 2 trans-oriented) and 8 tetrahedral sites characterize the 2:1 layer unit cell. Structures with all 6 octahedral sites occupied are known as trioctahedral (Fig. 2.4a) but if only 4 of the 6 octahedra are occupied, the structure is referred to as dioctahedral. Often, the structural formula is reported on the basis of the half unit-cell content, i.e. it is based on 3 octahedral sites.In the 1:1 or TM phyllosilicates (e.g., dioctahedral kaolinite and trioctahedral serpentine) each layer is about 7 Å (0.7 nm) thick. One surface of such a layer consists entirely of oxygen atoms (Ob) belonging to the tetrahedral sheet, while the other surface is composed of OH groups of the octahedral sheet (Fig. 2.3). In the 2:1 or TMT layer the tetrahedral sheets are inverted and two-thirds of the hydroxyl are replaced by tetrahedral apical oxygen atoms. The periodicity along the c-axis varies from 0.91 to 0.95 nm in talc and pyrophyllite, to 1.40–1.45 nm in chlorite. The higher values for chlorite is due to interlayer occupancy. In talc the interlayer space is empty but in mica and illite it is occupied by anhydrous alkaline and alkaline-earth cations (layer periodicity about 1.0 nm). The interlayer space of smectite and vermiculite contains alkaline or alkaline-earth cations together with water molecules (layer periodicity of: i) about 1.2 nm when the interlayer position is occupied by cations with low field strength and water molecules; ii)1.5 nm when the interlayer is occupied by high field strength cations and water molecules; iii) more than 1.5 nm when water molecules are exchanged by polar molecules with different size) whereas that of chlorite showing TMTMint (where Mint is the octahedral interlayer sheet) sequence is occupied by a continuous octahedral sheet. The chlorite layer periodicity is about 1.4 nm.The lateral dimensions of the tetrahedral sheet are usually greater than those of the octahedral sheet. The lateral misfit between the two sheets requires adjustment in one or both sheets, causing the layer structure to deviate from ideal hexagonal symmetry. The lateral dimensions of tetrahedra can be reduced in three ways: i) by rotating adjacent tetrahedra in the opposite direction as evaluated by the rotation angle alpha measuring the deviation from 120° of each angle in the ring; ii) by thickening the tetrahedral sheet thereby red

2006 - Crystal chemistry of some trioctahedral and dioctahedral micas coexisting in metamorphic sequences from N.W. Maine [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Guidotti, C. V.; Malferrari, Daniele; Sassi, F. P.
abstract

2006 - High temperature XAS study D. of Hg and Hg-cysteine complexes in montmorillonite and vermiculite [Relazione in Atti di Convegno]
Malferrari, Daniele; Brigatti, Maria Franca; Z. Y., Wu; W. H., Liu; G., Cibin; A., Marcelli
abstract

2006 - Interlayer material and its surrounding in micas: crystal chemical modeling and XANES spectroscopy [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Cibin, G.; Cinque, G.; Malferrari, Daniele; Marcelli, A.; Mottana, A.; Pini, Stefano; Poppi, Marco
abstract

2006 - Polarized XANES spectroscopy: The K edge of layered K-rich silicates [Articolo su rivista]
A., Marcelli; G., Cibin; G., Cinque; A., Mottana; Brigatti, Maria Franca
abstract

Angle-resolved XANES spectra have been collected at the potassium K edge using polarized synchrotron radiation on several natural mica crystals. Experimental data have been interpreted on the basis of the MS theory and, within this theoretical framework, the edge of this low-Z atom is decomposed so as to produce two partial patterns giving, respectively, the full in-plane absorption spectrum and the full out-of-plane one. The method here described is appropriate to describe the X-ray dichroic behaviour of solid layered compounds and/or two-dimensionally extended structures. (c) 2006 Elsevier Ltd. All rights reserved.

2006 - Poppiite, the V3+ end-member of the pumpellyite group: Description and crystal structure [Articolo su rivista]
Brigatti, Maria Franca; Caprilli, Enrico; M., Marchesini
abstract

Poppiite, a new mineral from Gambatesa mine (Val Graveglia, Genova, Northern Italy), is the V3+ end-member of the pumpellyite group [([VII])(Ca7.68Na0.27K0.03Rb0.02)(Sigma 8.00)([VI])(V1.263+Fe1.023+Mg0.78Mn0. 2+59Al0.31Cu0.042+)(Sigma 4.00)([VI])(V6.893+Al1.07Ti0.04)(Sigma 8.00)([IV])(Si11.69Al0 (.31))(Sigma 12.00)O-42(OH)(14); C2/m, a = 19.2889(6), b = 6.0444(2), c = 8.8783(3) angstrom, beta = 97.328(2)degrees, V = 1026.66(6) angstrom(3), D-meas = 3.36(2) g/cm(3), and D-calc = 3.44 g/cm(3)]. Poppiite crystals, with size varying from 0.1 to 0.6 mm, are minute, greenish-brown, and prismatic, and are associated with roscoelite, ganophyllite, manganaxinite, goldmanite, and calcite. The strongest lines in the X-ray powder diffraction pattern [d(abs) (angstrom), I-rel, (hkl)] are: 2.930, 100, (511); 3.817, 70, (202); 2.548, 65, ((3) over bar 13); 2.551, 62, (420); 1.612, 57, ((7) over bar 31,424); and 2.367, 51, (222, 403). Poppiite is optically negative, with 2V(calc) = 44 degrees, n(alpha) = 1.768(9), n(beta) 1.804(8), n(gamma) 1.810(9). The pleochroic scheme is a = light yellowish brown, = deep greenish brown, and gamma = brown to reddish brown. The crystal structure was refined using 1918 unique reflections to R = 0.0307. Like the other pumpellyite-group minerals the crystal structure of poppiite consists of chains of edge-sharing octahedra linked by SiO4, Si2O7, and CaO7 polyhedra.

2006 - Relationships between Fe2+/Fe3+ ordering and magnetic properties of micas [Relazione in Atti di Convegno]
Pini, Stefano; Brigatti, Maria Franca; Di Giocchino, D.; Marcelli, A.; Tripodi, P.
abstract

2006 - Soils under bilberry in the Frignano area (Modena Apennine) [Articolo su rivista]
Marchetto, Patrizia; Laurora, Angela; Malferrari, Daniele; Brigatti, Maria Franca; Bosi, Giovanna
abstract

2006 - Structure of Hg complexes in layer silicates: XAS and XRDP high temperature investigation [Relazione in Atti di Convegno]
Malferrari, Daniele; Brigatti, Maria Franca; Cibin, G.; Liu, W. H.; Marcelli, A.; Wu, Z. Y.
abstract

2006 - Summary of recommendations of nomenclature committees relevant to clay mineralogy: report of the Association Internationale Pour l'Etude des Argiles (aipea) nomenclature committee for 2006. [Articolo su rivista]
Guggenheim, S; Adams, Jm; Bain, Dc; Bergaya, F; Brigatti, Maria Franca; Drits, Va; Formoso, Mll; Galan, E; Kogure, T; Stanjek, H.
abstract

Brindley et al. (1951) reported the earliest efforts to obtain international collaboration on nomenclature and classification, initiated at the International Soil Congress in Amsterdam in 1950. Since then, national clay groups were formed, and they proposed various changes in nomenclature at group meetings of the International Clay Conferences. Most of the national clay groups have representation on the Nomenclature Committee of the Association Internationale Pour L’Etude des Argiles (AIPEA, International Association for the Study of Clays) Nomenclature Committee, which was established in 1966, and no longer have ad hoc nomenclature committees. The precursor committee to the AIPEA Nomenclature Committee was the Nomenclature Subcommittee of the Comite Internationale Pour L’Etude Des Argiles (CIPEA, International Committee for the Study of Clays). The AIPEA Nomenclature Committee has worked closely with other international groups, including the Commission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (IMA), which is responsible for the formal recognition of new minerals and mineral names, and the International Union of Crystallography (I.U.Cr), which considered extensions to the nomenclature of disordered, modulated and polytype structures (Guinier et al., 1984) published earlier by a joint committee with the IMA (Bailey, 1977). In contrast to the other national clay groups, however, The Clay Minerals Society (CMS) Nomenclature Committee, which was established in 1963 at the same time as the CMS and predates the AIPEA Nomenclature Committee, remains in existence and occasionally produces recommendations. The precursor to this committee was the Nomenclature Sub-Committee, which was organized in 1961 by the (U.S.) National Research Council. The Chair of the AIPEA Nomenclature Committee is a standing member of the CMS Nomenclature Committee so that the committees are in close contact. The purpose of the AIPEA Nomenclature Committee has been to make general and specific recommendations concerning a) definitions of mineralogical and crystallographic clay-related terms, b) classification and terminology of clays, clay minerals and related terms, c) standardization of structural and descriptive terms, d) species, subgroup, and group names, e) the establishment of procedures/criteria for determining species, f) the emphasis (or re-emphasis) of the proper use of terms, and g) any additional aspects relating to nomenclature. Approximately twelve published reports have been presented since the 1950s. However, an additional twelve unpublished reports have been archived, and many committee papers have been written by guest members asked to join the committee to help resolve a specific issue or by committee members to help lead the discussion of a specific topic. Although the latter papers have not been published, many illuminate the rationale behind recommendations. In addition, they may also show insight in areas still in need of additional research. In general, the Committee is not expected to provide research to reach a recommendation. Instead, where sufficient data are unavailable, the Committee may (or may not) note the insufficiency and postpone any further comment. Thus, extensive committee papers may have been written, only to conclude that comment should be deferred.

2006 - Summary of recommendations of nomenclature committees relevant to clay mineralogy: report of the Association Internationale pour l'Etude des Argiles (AIPEA) Nomenclature Committee for 2006 [Articolo su rivista]
S., Guggenheim; J. M., Adams; D. C., Bain; F., Bergaya; Brigatti, Maria Franca; V. A., Drits; M. L. L., Formoso; E., Galan; T., Kogure; H., Stanjek
abstract

Brindley et al.(1951) reported the earliest efforts to obtain international collaboration on nomenclature and classification of clay minerals, initiated at the International Soil Congress in Amsterdam in 1950. Since then, national clay groups were formed, and they proposed various changes in nomenclature at group meetings of the International Clay Conferences. Most of the national clay groups have representation on the Nomenclature Committee of the Association Internationale pour l’Etude des Argiles (AIPEA, International Association for the Study of Clays), which was established in 1966. The precursor committee to the AIPEA Nomenclature Committee was the Nomenclature Subcommittee of the Comité International pour l’Etude des Argiles (CIPEA, International Committee for the Study of Clays). The AIPEA Nomenclature Committee has worked closely with other international groups, including the Commission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (IMA), which is responsible for the formal recognition of new minerals and mineral names, and the International Union of Crystallography (IUCr), which considered extensions to the nomenclature of disordered, modulated and polytype structures (Guinier et al., 1984) published earlier by a joint committee with the IMA (Bailey, 1977). In contrast to the other national clay groups, however, The Clay Minerals Society (CMS) Nomenclature Committee, which was established in 1963 at the same time as the CMS and predates the AIPEA Nomenclature Committee, remains in existence and occasionally produces recommendations. The precursor to this committee was the Nomenclature SubCommittee, which was organized in 1961 by the (US) National Research Council. The Chair of the AIPEA Nomenclature Committee is a standing member of the CMS Nomenclature Committee so that the committees are in close contact.

2006 - The effect of different plasma gas environments on vermiculite layer [Relazione in Atti di Convegno]
Valdrè, G.; Malferrari, Daniele; Marchetti, Diego; Brigatti, Maria Franca
abstract

2006 - Thermal behavior of Cu(II)-, Cd(II)-, and Hg(II)-exchanged montmorillonite complexedwith cysteine [Articolo su rivista]
Malferrari, Daniele; Brigatti, Maria Franca; Laurora, Angela; Medici, L; Pini, Stefano
abstract

The thermal behavior of montmorillonite and organically modified montmorillonite, both treated with heavy metal cations [Cu(II), Cd(II) and Hg(II)], was characterized via thermal analyses (TG, DTG and DTA) combined with evolved species gas mass spectrometry (MS-EGA), and X-ray diffraction at in situ controlled temperature (HTXRD). The reactions involving Cu(II)-and Cd(II)-montmorillonite samples are mostly related to H2O and OH loss, unlike Hg(II)-montmorillonite, where effects associated to Hg(II) loss are also present. Finally reactions related to dehydration, dehydroxylation and to organic matter decomposition can be observed in montmorillonite samples treated with cysteine.

2006 - Titanian phlogopite from Presidente Oleario (Southeastern Brazil): New crystal chemical data [Relazione in Atti di Convegno]
Sabato, A.; Scordari, F.; Brigatti, Maria Franca
abstract

2005 - Adsorption of [Al(Urea)(6)](3+) and [Cr(Urea)(6)](3+) complexes in the vermiculite interlayer [Articolo su rivista]
Brigatti, Maria Franca; Laurora, Angela; Malferrari, Daniele; Medici, Luca; Poppi, Luciano
abstract

This work investigates the interaction between vermiculite and urea metal complexes {[Cr(Urea)(6)](3+) and [AI(Urea)(6)](3+)} via several techniques, including: i) chemical analyses; ii) X-ray diffraction at controlled temperature; iii) microdiffraction on selected crystal areas; iv) thermal analyses and mass spectrometry of evolved species during heating; v) atomic force microscopy; vi) micro-FTIR. Organo-clay complexes were prepared both at room (25 C) and 60 degrees C temperature. Vermiculite treated with [Al(Urea)(6)](3+) showed a complete adsorption of the complex at room temperature, unlike vermiculite treated with [Cr(Urea)(6)](3+) where only a partial exchange was observed. The X-ray investigation evidenced disordered sequences in the layer stacking as common in vermiculite treated with [Al(Urea)6](3+) and [Cr(Urea)(6)](3+) at 60 degrees C. Stacking disorder is present also at room temperature when complexed with [Cr(Urea)(6)](3+) solutions. Microdiffraction investigation identified several domains in vermiculite treated at 60 degrees C. This evidence is also reinforced by FTIR spectroscopy data, which revealed the presence of ammonium isocyanate.

2005 - Analisi Termica, Capitolo IX. [Capitolo/Saggio]
Brigatti, Maria Franca
abstract

non disponibile

2005 - Applied Clay Science, Volume 28, Issues 1–4, Pages 1-324 [Direzione o Responsabilità Riviste]
Brigatti, Maria Franca
abstract

2005 - Cation-site partitioning in Ti-rich micas from Black Hill (Australia): A multi-technical approach [Articolo su rivista]
E., Schingaro; F., Scordari; Brigatti, Maria Franca; E., Mesto; G., Pedrazzi
abstract

The crystal chemistry of Ti-rich trioctahedral micas of plutonic origin, cropping out at Black Hill (South Australia) has been investigated by combining electron microprobc analysis, single crystal X-ray diffraction, Mossbauer spectroscopy and X-ray photoelectron spectroscopy. Chemical analyses have shown the samples taken to be quite homogeneous and Ti-rich (TiO2 approximate to 7 wt.%). Mossbauer investigation yielded Fe2+/Fe3+ approximate to 30. X-ray photoelectron spectroscopy analysis seems to suggest the occurrence of three Ti species: octahedral Ti4+(60%), octahedral Ti3+(26%), and tetrahedral Ti4+( 14%). The analyzed sample belongs to the 1Mpolytype and the relevant crystal data front structure analysis are: a 5.347(l) angstrom, b = 9.261(2) angstrom, c = 10. 195(2) angstrom,beta - 100.29 degrees (1). Anisotropic structure refinement was performed in space group C2/m, and converged at R 2.62, R-w - 2.80. Structural details (the c cell parameter, the off-center shift of the M2 cation towards O4, the bond-length distortions of the cis-M2 octahedron, the interlayer sheet thickness, the projection of K-O4 distance along c*, the difference < K-O >(outer)< K-O >(inner)) support the occurrence of the Ti-oxy substitution (R-VI(2+) + 2(OH)(-) reversible arrow Ti-VI(4+) + 2O(2-) + H-2) in the sample. Analysis of structural distortions as a function of the Ti content revealed that the positions of the oxygens 03 and 04 are displaced in opposite senses along [100]. This produces an enlargement of the M1 site with respect to the M2 site and a shortening of the interlayer distance. This trend seems to be in common with other Ti-rich 1M micas of plutonic origin.

2005 - Crystal Chemical Models on Trioctahedral and Dioctahedral Micas [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Guggenheim, S.; Laurora, Angela; Malferrari, Daniele; Poppi, M.; Poppi, Luciano
abstract

2005 - Crystal Structure and Chemistry of trilithionite-2M2 and polylithionite-2M2 [Articolo su rivista]
Brigatti, Maria Franca; Caprilli, Enrico; Malferrari, Daniele; Medici, Luca; Poppi, Luciano
abstract

The crystal chemistry of three Li-bearing mica-2M(2) crystals from pegmatites has been studied by chemical analyses and single crystal X-ray diffraction; their belonging to the trilithionite-polylithionite join is highlighted by the following compositional ranges in atoms per formula unit [based on O12-(x+y) (OH)(x)F-y] : 3.198 <= Si <= 3.538, 0.462 <= [IV]Al <= 0.811, 1.195 <= [IV]Al <= 1.390, 0.031 <= (Fe+Mn) <= 0.072, 1.522 <= Li <= 1.757, 0.872 <= K <= 0.906, 0.030 <= Na <= 0.073, 0.000 <= (Cs+Rb) <= 0.099, 1.541 F <= 1.722. The correlation between F and Li content is confirmed, as observed in Li-rich micas. Crystal structure refinements were carried out in space group C2/c (R values vary between 0.030 and 0.03 1). The crystal chemistry is mostly influenced by tetrahedral chemical composition. Increasing [IV]Al content, cc and psi(MI) parameters increase; Si content involves a lowering of the interlayer separation and tetrahedral thickness. Li content affects octahedral thickness. The stability of 2M(2) polytype seems to be induced by a relative increase of Delta z tetrahedral parameter, which reduces the repulsion between basal tetrahedral oxygen atoms. Unlike Li-bearing muscovite, trioctabedral Li-bearing mica crystals show an octahedral occupancy not related to octahedral charge.

2005 - Crystal chemistry of ferroan phlogopites from the Albano maar lake (Colli Albani volcano, central Italy) [Articolo su rivista]
Brigatti, Maria Franca; Caprilli, Enrico; R., Funiciello; G., Giordano; A., Mottana; Poppi, Luciano
abstract

This work considers micas present both as phenocrysts in granular xenoliths and as large xenocrysts in the phreatomagmatic deposits, which characterize the final volcanic activity of Colli Albani volcanic complex, Roman Comagmatic Region (central Italy). In these micas the Fe/(Fe+Mg) ratio spans from 0.06 to 0.55, thus the micas range from phlogopite to magnesian annite through ferroan phlogopite. Heterovalent octahedral substitutions involve Ti, At and also Cr but in very limited amounts. In the interlayer, Ba for K substitution occurs up to 0.06 apfu. Crystal structure refinements were determined in space groups C2/m and C2/c for the 1M and 2M(1) polytypes, respectively (agreement factor, R-obs: 0.021 <= R-obs <= 0.035). The crystal structure of these micas is greatly affected by the annitic substitution. An increase in the annitic component is reflected by a decrease in distortion affecting both individual tetrahedra (tetrahedral angle variance, TAV:0.49 <= TAV <= 1.13 degrees(2)) and the entire tetrahedral ring [6.6 <=alpha <= 10.34 degrees]. The interlayer topology is affected as well. A strong correlation exists between Fe and Ti; thus, the same correlations found for Fe apply to Ti also. Another strong correlation exists between heterovalent octahedral substitutions and the (OH)- site deprotonation. In contrast, heterovalent interlayer substitutions are accompanied by substitution of F- for (OH)-. Despite their scattered occurrence in pyroclastics, these micas nicely represent the overall crystal chemical trends of micas, which re-crystallized undisturbed in magma before this reached explosive conditions. One crystal of the dataset considered may represent a phenocryst in a hypabissal body disrupted by one of the many explosive phases of the Alban Hills volcanism.

2005 - Interactions of Mica and Vermiculite Layers with Ionized Gasses [Relazione in Atti di Convegno]
Marchetti, Diego; Brigatti, Maria Franca; Laurora, Angela; Malferrari, Daniele; Valdré, G.
abstract

2005 - Mercury adsorption by montmorillonite and vermiculite: a combined XRD, TG-MS, and EXAFS study. [Articolo su rivista]
Brigatti, Maria Franca; Colonna, S.; Malferrari, Daniele; Medici, Luca; Poppi, Luciano
abstract

Synchrotron based extended X-ray absorption fine structure spectroscopy (EXAFS), X-ray diffraction at room and high temperature, thermal analyses combined with mass spectrometry of evolved gas, and chemical analyses contributed to assess the influence of mercury on montmorillonite and vermiculite layers. The adsorbed Hg amount was higher for montmorillonite (Hg = 37.7 meq/100g) than for vermiculite (Hg = 28.0 meq/100g). The basal spacing for the Hg treated samples was 15.2 (montmorillonite) and 14.5 Å (vermiculite). Thermal and evolved gas spectrometry analyses suggest that Hg was released at T  230°C and at 600°C for montmorillonite, but at 550, 800 and 860°C for vermiculite. The effect of temperature on Hg release is also apparent when the basal spacing at 230°C for montmorillonite (d001 = 10.3 Å) is compared to that for vermiculite (d001 = 11.8 Å).EXAFS analyses provide qualitative evidence that oxygen atoms occupy the first coordination shell of Hg in both clay minerals. The best fit between observed and calculated spectra is obtained when montroydite is assumed as a reference model compound

2005 - Micas@Italy Crystal chemistry, petrology, spectroscopy, strucutre, microstrutture and application of micas [Altro]
Brigatti, Maria Franca; G., Ivaldi; A., Mottana; A., Pavese; F. P., Sassi; R., Sassi; F., Scordari
abstract

Convegno dedicato alle miche, tenutosi a Rimini 9-11 febbraio 2005

2005 - Modification of Hg-H2O and Hg-cysteine complexes in layered structure with temperature: an X-ray, thermal and XAS study [Relazione in Atti di Convegno]
Malferrari, Daniele; Brigatti, Maria Franca; Cibin, G.; Marcelli, A.; Chu, W. S.; Wu, Z.
abstract

2005 - Modification of vermiculite surface by ionized gasses [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Laurora, Angela; Malferrari, Daniele; Marchetti, Diego; Valdré, G.
abstract

2005 - Potassium coordination in trioctahedral micas investigated by K-edge XANES spectroscopy [Articolo su rivista]
G., Cibin; A., Mottana; A., Marcelli; Brigatti, Maria Franca
abstract

Fine-grained homogeneous powder samples of thirteen trioctahedral micas, mostly intermediate members of the phlogopite - annite solid solution series, and samples close to the phlogopite, fluor-phlogopite and tetra-ferriphlogopite end members have been examined at the potassium K-edge by X-ray absorption fine structure spectroscopy. The interlayer K+ cation is in a coordination that is certainly lower than 12, in contrast to what is expected from the ideal hexagonal symmetry model of the mica structure, and approaches - but it does not reach - coordination 6, as it should be when the effective ligands are the three nearest outer bridging oxygens of two facing upper and lower tetrahedral sheets. The observed range of coordinations implies that only some of the three inner bridging oxygen atoms in each sheet are involved, thus leading to 6 +/-(1...6) effective configurations depending on the composition of the individual mica terms. The effective coordination number was found to vary continuously with composition from 11 to 7 and to be related to the tetrahedral rotation angle (alpha) according to two different linear relationships for the phlogopite - annite series (Fe2+Mg-1 exchange vector, involving the octahedral sheet only) and the phlogopite - tetra-ferriphlogopite series (Fe3+Al-1 vector, involving the tetrahedral sheet), respectively. Substitutions affecting either the A cation in the interlayer or the X anion in the octahedral sheet also affect the observed trends. In particular, the latter substitution effect is best seen in two near end member phlogopites, where the fluorine to hydroxyl substitution (F- (OH)(-)(-1) exchange vector), which greatly changes the alpha tetrahedral rotation angle is, reflected in the experimental K XANES spectra by modifying not only the energy but also the intensities of most multiple scattering features.

2005 - Reactions of Cd Ions and Cysteine in Aqueous Solutions with Vermiculite [Relazione in Atti di Convegno]
Pini, Stefano; Brigatti, Maria Franca; Laurora, Angela; Malferrari, Daniele; Medici, L.
abstract

2005 - Sorption kinetics and chemical forms of Cd(II) sorbed by thiol-functionalized 2:1 clays [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Laurora, Angela; Malferrari, Daniele; Medici, L.; Pini, Stefano
abstract

2005 - Structure and crystal chemistry of the micas: new advancements and possible interface to clay science [Relazione in Atti di Convegno]
Brigatti, Maria Franca
abstract

2005 - Study of natural and ion exchanged montmorillonite by thermal analysis (TGA) and evolved gas mass spectrometry (MSEGA) [Abstract in Rivista]
Brigatti, Maria Franca; Laurora, Angela; Malferrari, Daniele; S., Pini
abstract

Presentazione a poster nella sessione "GEO06- Mineralogia- Mineralogy" tenutasi a Spoleto il 23 settembre 2005 in occasione di Geoitalia 2005

2005 - The 2M1 Dioctahedral Mica Polytype: A Crystal Chemical Study [Relazione in Atti di Convegno]
Poppi, M.; Brigatti, Maria Franca; Malferrari, Daniele
abstract

2005 - The 2M1 dioctahedral mica polytype: a crystal chemical study [Articolo su rivista]
Brigatti, Maria Franca; Malferrari, Daniele; Poppi, Marco; Poppi, Luciano
abstract

The structure of dioctahedral true micas such as muscovite and celadonitic muscovite (2M1 polytype, Space Group C2/c) is mostly affected by variations of the octahedral Al content ([vi]Al). Crystals with greater Mg, Fe substitutions (i.e., celadonitic muscovite) reduce the dimensional difference between the larger trans-oriented M(1) site and smaller cis-oriented M(2) octahedral site. The octahedral anionic position O(4) is displaced from the center of the hexagon, defined by O(31) and O(32) oxygen atoms (i.e., “octahedral hexagon”), both on and off the (001) plane. The distance between interlayer cation A and O(4) is smaller in more substituted species, thus providing different orientations of the O(4)-H vector, as a function of [vi]Al. Octahedral distances and are expressed as a function of cell parameters and [vi]Al content, thus allowing an approximate estimate of site dimensions. These approximations are useful when a detailed structural refinement is not available. In celadonitic muscovite, the octahedral hexagon mean edge is not significantly affected by [vi]Al content. The [vi]Al increase produces both a decrease in cell lateral dimensions and a distorted “octahedral hexagon”. The decrease in a and b is consistent with a decrease of , whereas the distortion of the “octahedral hexagon” is consistent with an increase of , because an irregular hexagon produces a longer mean edge than a regular hexagon of equal area.The tetrahedral mean basal edge is reduced as celadonitic substitution progresses. The tetrahedral rotation angle was thus found to increase from celadonite to muscovite. However in muscovite with [vi]Al content between 1.8 and 2.0 atoms per formula unit (apfu), approaches a saturation value, thus showing a proportional increase of tetrahedral and octahedral sheet lateral dimensions. Furthermore, alpha variation allows a coarse approximation of the threshold [vi]Al content, below which celadonitic substitution may not progress.

2005 - Trilithionite-2M2 and Polylithionite-2M2: a Crystal Chemical Study [Relazione in Atti di Convegno]
Medici, L.; Brigatti, Maria Franca; Caprilli, Enrico; Malferrari, Daniele
abstract

2005 - Trioctahedral and Dioctahedral Micas Coexisting in Metamorphic Sequences from Maine [Relazione in Atti di Convegno]
Malferrari, Daniele; Benincasa, E.; Brigatti, Maria Franca; Guidotti, C. V.
abstract

2005 - Trioctahedral micas in volcanic rocks from Mt. Sassetto (Tolfa area, Central Italy) [Abstract in Rivista]
Brigatti, Maria Franca; Caprilli, Enrico; Laurora, Angela; Malferrari, Daniele; L., Medici; A., Mottana
abstract

Presentazione a poster nella sessione "GEO06- Mineralogia- Mineralogy" tenutasi a Spoleto il 23 settembre 2005 in occasione di Geoitalia 2005

2005 - Trioctahedral micas in volcanic rocksfrom Mt. Sassetto (Tolfa area, Central Italy) [Relazione in Atti di Convegno]
Laurora, Angela; Baschieri, S.; Brigatti, Maria Franca; Caprilli, Enrico; Mottana, A.
abstract

2005 - XANES study of Hg sorption products on montmorillonite at high temperatures [Articolo su rivista]
Chu, W. S.; Wu, Z. Y.; Liu, W. H.; Malferrari, Daniele; Brigatti, Maria Franca; Cibin, G.; Marcelli, A.
abstract

The Hg L3-edge XANES spectra of montmorillonite treated with Hg(NO3)2 0.01M aqueous solution and the mixing solution of Hg(NO3)2 0.01M aqueous solution and cysteine 0.01M aqueous solution have been measured at several high temperatures. The adsorption and desorption of mercury in Hg-rich montmorillonite minerals and the effect of cysteine on the adsorption of mercury by this clay mineral were studied. Our analysis shows that mercury is six fold coordinated by water molecules and the oxygen atoms of montmorillonite surface without the amino acid introduction. Mercury atoms prefer to bond with sulphur atoms of the amino acid cysteine to form more stable Hg-S bonds when the amino acid cysteine has been introduced. This result suggests that the treatment with the amino acid enhances the stability of mercury sorbed by the montmorillonite mineral and efficiently retard the release of mercury ions into the geosphere.

2004 - Characterization of Cu-complexes in smectite with different layer charge location: Chemical, thermal and EXAFS studies [Articolo su rivista]
Brigatti, Maria Franca; S., Colonna; Malferrari, Daniele; L., Medici
abstract

The retention of Cu and Cu-amino acid complexes by montmorillonite and beidellite, before and after repeated acidified aqueous solution treatments, was studied using X-ray diffraction, chemical and thermal analyses, mass spectrometry and synchrotron-based X-ray absorption spectroscopy (XAS). The results indicate that the extraction of metal complexes from smectites depends on the nature of the layer charge and on the kind of organic species. Cu-cysteine complexes are strongly retained in the interlayer position, whereas Cu-glycine complexes are mostly adsorbed in cationic form which can be easily removed from the silicate layer. The layer periodicity for Cu-smectites treated with glycine shows little or no layer expansion, whereas significant swelling of the layer periodicity is observed in smectites treated with cysteine. Thermal decomposition of both smectites with sorbed Cu-amino acid species shows the evolution of H2O, NO, CH3CH3, and CO2. In Cu-cysteine treated smectites, the release of H2S, NO2, SO2, and N2O3 also occurs. X-ray absorption spectroscopy (XAS) was used to assess the relationships between the structure of the Cu complexes and their desorption from smectites. In Cu-exchanged smectites, the first coordination shell agrees with the hypothesis that the Cu coordinates to oxygen atoms to form monomer and/or dimer complexes. The first coordination shell of Cu in smectites treated with glycine shows four atoms at distances of similar to2 Angstrom. Two of these bonds are with nitrogen and two with oxygen atoms. For copper-cysteine complexes XAS data are compatible with the existence of Cu-N clusters, thus suggesting that Cu links to the amino acid by the aminic group. Copyright

2004 - Crystal Chemistry of Apatite Coexisting With Phlogopite and Tetra-Ferryphlogopite [Abstract in Rivista]
Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Ottolini, L.; Poppi, Luciano
abstract

2004 - Crystal Chemistry of Apatites from the Tapira carbonatite complex, Brazil [Articolo su rivista]
Brigatti, Maria Franca; Malferrari, Daniele; Medici, Luca; Ottolini, L.; Poppi, Luciano
abstract

The crystal chemistry of ten hydroxyl fluorapatite crystals from the Tapira alkaline carbonatitic complex (Brazil) was investigated by electron microprobe, ion microprobe, infrared spectroscopy and single crystal X-ray diffraction. Apatite crystals are characterized by modest REE and a very low Cl content. They exhibit the following compositional range in atoms per formula unit was determined to be 9.935  Ca  10.024, 5.926  P  6.006, 0.005  REE  0.046, 0.422  F  0.914, 0.003  Cl  0.008, 0.003  Si  0.038; Na is present in trace.Crystal structure refinements were carried out in space group P63/m, (R values varies between 0.016 and 0.028). The REE for Ca substitution requires two different exchange mechanisms producing an increase in the bond valence on the X anionic site: the deprotonation of OH and/or the substitution of for OH. The substitution in the anionic sites of investigated structures was related to great CO2 activity of the melt whereas deprotonation of the apatite crystals could be related to the highly oxidizing nature of the Tapira carbonatitic magma. The very low Cl/F ratio suggests that the crystallization of Tapira pluton was relatively shallow. The determination of REE partitioning between the Ca1 and Ca2 sites is difficult because of the low REE content. A proportional increase in the size of the Ca1 and Ca2 sites was observed with increasing REE content as well as an overall increase of a parameter

2004 - Nb-containing titanite: new data and crystal structure refinement [Articolo su rivista]
Brigatti, Maria Franca; Caprilli, Enrico; A., Mottana; Poppi, Luciano
abstract

Nb-containing titanite, Si-[4](1.000) ([6])(Ti-0.748 Al-0.095 Zr-0.045 Nb-0.041 Ta-0.001 Fe-0.067(3+) Sn-0.002 Sb-0.001)(1.000) ([7])(Ca-0.986 Ce-0.004 La-0.001 Mn-0.004 Na-0.005 K-0.001)(1.001) F-0.055 (OH)(0.065) O-4.880, from San Vito quarry, Mt. Somma, Naples, Italy, is characterised by extensive substitutions in the six- and seven-fold coordination sites. Single-crystal X-ray diffraction study indicates this niobian titanite to be monoclinic (a = 6.557(l), b = 8.701 (1), c = 7.077(l) Angstrom, beta = 113.86degrees) with C2/c symmetry. Crystal structure refinement (agreement factor, R = 0.027) suggests that the substitution mechanism (Al, Fe)(3+) + (Nb, Ta)(5+) = 2Ti(4+) is primarily responsible for the incorporation of pentavalent metal ions in the octahedral site.

2004 - Octahedral low spin symmetric configurations vs. high spin octahedral distorted configurations: the case of Fe in natural layered silicates [Articolo su rivista]
A., Marcelli; G., Cibin; S., Di Matteo; J., Chaboy; D., Di Gioacchino; P., Tripodi; Brigatti, Maria Franca; A., Mottana; M. L., Marco
abstract

We performed a full series of DC and AC magnetic measurements, as well as X-ray absorption spectroscopy (XAS) study, on a set of mica samples with variable total iron content in order to characterize their electronic, magnetic and structural properties. We found a magnetic phase transition at T-c similar to 110 K only for a specific Fe2+/Fe3+ occupancy ratio (1.65) of the tetrahedral and octahedral sheets and showed that the magnetic behavior for such a material is strongly anisotropic if measured along the mica planes or orthogonally to them. Moreover, the AC magnetic measurements gave a definite evidence of the transition as a history-dependent phenomenon. Finally, we tried to give a theoretical explanation of our observations in terms of a Hubbard Hamiltonian in an octahedral crystal field. Our conclusions definitively rule out a high-spin to low-spin iron transition. An order-to-disorder phase transition can be a possible alternative mechanism, to be confirmed by future experiments.

2004 - “Cu, Cd, Hg and Cu-, Cd-, Hg-cysteine treated montmorillonite and vermiculite crystals: an EXAFS study. [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2003 - A crystal-chemical investigation of Cr substitution in muscovite by XANES spectroscopy. [Articolo su rivista]
A., Cardelli; G., Cibin; M., Benfatto; S., Della Longa; Brigatti, Maria Franca; A., Marcelli
abstract

This work introduces a novel procedure to fit the scattering features of XANES spectra. The procedure was applied and validated on, a chromium-containing muscovite for which structural and crystal-chemical characterization is available from literature. The simulation, which involved clusters formed by up to 90 atoms, proved to be effective in representing the Cr local environment, even if the system is characterized by a very low metal content, as demonstrated by the extremely good correspondence with experimental data.

2003 - A multy-technical approach to get a careful cation site partition in Ti-rich micas [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Rinaldi, A.; Scordari, F.
abstract

2003 - A polarized XANES investigation of Mg-rich trioctahedral micas [Relazione in Atti di Convegno]
Tombolini, F.; Cibin, G.; Marcelli, A.; Mottana, A; Brigatti, Maria Franca; Giuli, G.
abstract

In this work we analyse the polarized Mg and Fe K-edge XANES spectra obtained on single crystals of phlogopite, (sample from Franklin, New Jersey), and of tetra-ferriphlogopite (sample from Tapira, Alto Paranaíba, Brazil). These crystals show composition close to the end-members, thus they present similar chemical composition in octahedral and interlayer position, but they differ for tetrahedral substitutions. Our aim is thus to discover the influence of the different chemical composition of the T sheet on the M sheet topology. To reach this goal, as the differences observed in the XANES spectra when changing the beam incidence angle are associated with the different contributions of the photoelectron pathways involving the absorber atom and its near and next-near-shell neighbours in the direction of the electric field vector, we investigated the angular dependence of the spectral XANES features at the Mg and Fe K edges .

2003 - Al(urea)63+ and Cr(urea)63+ interactions with vermiculite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Dilillo, M.; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2003 - An EXAFS study on smectites exchanged with organo-metallic complexes [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2003 - Chlorites crystal chemistry: new data and crystal structure refinements [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Caprilli, Enrico; Poppi, Luciano
abstract

2003 - Crystal chemistry of Ferroan Phlogopite-1M and 2M1 crystals from the Alban Hills Volcano (Central Italy) [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Caprilli, Enrico; Giordano, G.; Mottana, A.; Poppi, Luciano
abstract

2003 - Crystal chemistry of dioctahedral micas from peraluminous granites: The pedrobernardo pluton (Central Spain). [Articolo su rivista]
Benincasa, Emanuele; Brigatti, Maria Franca; Poppi, Luciano; Bea Barredo, F.
abstract

The aim of this work is an introductory study on the crystal chemistry of igneous muscovite, with particular focus on samples from the Pedrobernardo pluton (central Spain), whose crystal structure and chemistry is compared with data from literature. This pluton is a layered sheet-like granite body with distinct horizontal zoning and it can be subdivided into three main zones (lower, middle, and higher zone) characterized by different crystallization conditions. When chemical composition of muscovite from Pedrobernardo pluton is compared to literature data, different chemical trends can be pointed out. Samples from middle and lower zones follow a same trend, whereas samples from higher zone follow another. In samples from middle and lower zones Ti4+ increases without affecting Fe content (Fe2+ and/or Fe3+, thereafter referred to as Fe). Fe and Mg2+ can enter into the layer in similar amount. In samples from higher zone Ti4+ content is lower than in lower and middle zones, whereas Fe is higher. Fe content is related to Ti4+ content and Fe seems to substitute for octahedral Al3+ more easily than Mg2+. Samples from the middle and lower zones are characterized by substitutions involving both tetrahedral and octahedral sites, whereas samples from higher zone are characterized by a preference for octahedral substitutions. Single crystal structure refinements suggest a partial occupancy of the octahedral trans-site (M1) related to F- for OH- substitution and probably to a different O-H vector orientation. Lateral cell parameters are found to be affected by the octahedral cis-site mean bond distance (M2-O), which, for a great number of samples under consideration is linked to Fe2+ content. M1-O distance as well as tetrahedral thickness was found to be affected by the c parameter, following the structural mechanisms induced by chemical substitutions previously described.These parameters seem thus to be affected more by electrostatic interactions involving the whole layer rather than by site occupancy and local chemical composition.

2003 - Crystal chemistry of the 1M mica polytype: The octahedral sheet [Articolo su rivista]
Brigatti, Maria Franca; S., Guggenheim; Poppi, Marco
abstract

This work provides a crystal-chemical description of the trioctahedral sheet in 1M mica polytypes of C2/m symmetry. Some octahedral parameters were found to be related strictly to octahedral chemical composition, whereas others were related to the overall layer chemistry. As a general rule, the M I site is more affected by octahedral chemical composition than the M2 site, and octahedral distortions are more affected than octahedral size. This behavior is attributed to the constraints related to edge-sharing octahedra and octahedral-tetrahedral coupling, which involves the sharing of the apical tetrahedral oxygen atom between the tetrahedron and octahedron. A more quantitative explanation was sought by considering expressions that relate octahedral parameters as a function of atomic coordinates and unit-cell parameters. This procedure identified those parameters affected by local distortions and those that are a function of a more global effect and whose variation greatly affects the layer. Local distortions are obviously more likely a result of local chemical composition. The size and distortion of the octahedral sheet seem to be independent for the database of samples considered. The alpha angle was found to be a complex parameter required to: (1) fit tetrahedral and octahedral lateral dimensions; (2) fit tetrahedral topology to its local chemical composition, and (3) fit the interlayer cation electrostatic interactions.

2003 - Crystal structure and chemistry of lithium-containing trioctahedral micas-3T. [Articolo su rivista]
Brigatti, Maria Franca; De, Kile; Poppi, Luciano
abstract

Chemical analyses and crystal structure refinements were performed on lithian siderophyllite-3T crystals from granitic pegmatites of the anorogenic Pikes Peak batholith (Colorado) to characterize the crystal chemistry and relations with trioctahedral lithium-bearing micas showing different stacking sequences. Chemical data show that the studied samples fall on the siderophyllite-polylithionite join, closer to the siderophyllite end-member. Single-crystal X-ray refinements were carried out on three samples (two of which were taken from core and rim of the same crystal) in space-group P3(1)12 (the agreement factor, R-obs, varies between 0.034 and 0.036). Mean bond distances and mean electron counts of M1, M2 and M3 octahedral sites indicate an ordered cation distribution with M1 and M3 positions substantially larger than M2. In the sample with the largest iron content, the M2 mean electron count increases as well as the <M2-O> mean distance, whereas <M2-O> remains smaller than <M1-O> or <M3-O>. The tetrahedral cation-oxygen atom mean distances range from 1.614 to 1.638 Angstrom and from 1.663 to 1.678 Angstrom for T1 and T2 sites, respectively, being consistent with Al3+ enrichment in the T2 sites. The tetrahedral rotation angle, a, is generally small (3.1 less than or equal to alpha less than or equal to 4.6) and decreases with siderophyllite content. As Fe increases, the T1 tetrahedron becomes flatter (112.4 less than or equal to tau(T1) less than or equal to 110.5), whereas T2 tetrahedron distortion appears unchanged (110.7 less than or equal to tau(T2) less than or equal to 110.9).

2003 - Crystal structure refinement of IIb-4 clinochlore [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Caprilli, Enrico; Poppi, Luciano
abstract

2003 - Different organo-metallic species following to Hg, Cu and cysteine treatment on montmorillonite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Colonna, S.; Malferrari, Daniele; Medici, L.
abstract

2003 - EXAFS analysis of montmorillonite and beidellite intercalated with Cu-amino acid complexes: modelling and experiments [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2003 - Effect of amino acids on the retention of copper by beidellite [Articolo su rivista]
Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

The evaluation of environmental hazards related to Cu in urban and industrial run-off, as well as the introduction of possible technologies for the remediation of environmentally compromised areas should not be dealt independently form a sound understanding of structural features of the different interacting species. Low cost clay-minerals are potentially very promising materials for effectively exchanging and stoking Cu. A low cost beidellite was thus evaluated. The mineral behavior in accomplish its function is completely different for the natural and for amino acid complexed sample, with a major influence of the amino acid itself. Different experimental techniques were thus introduced: namely chemical, X-ray diffraction, thermal, mass spectrometry and X-ray absorption spectroscopy analyses. All the knowledge thus acquired on natural and treated species was thus finally related to their adsorption and retention capacity.

2003 - Euroclay 2003 [Altro]
Brigatti, Maria Franca; Manfredini, Tiziano
abstract

10th Conference of the European Clay Groups Association

2003 - Hg - cysteine complex sorbed by smectites - a combined XRD, TG-MS, and EXAFS study [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2003 - Le caratteristiche cristallochimiche dei fillosilicati nelle applicazioni industriali e nella protezione dell’ambiente [Relazione in Atti di Convegno]
Brigatti, Maria Franca
abstract

2003 - Magnetic Properties of Iron-Bearing Micas [Relazione in Atti di Convegno]
Marcelli, A.; Cibin, G.; DI GIOACCHINO, D.; Chaboy, J.; Mottana, A.; Brigatti, Maria Franca
abstract

2003 - Structural and chemical modification induced in rectorite treated with Hg(II), Cd(II) and cysteine [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2003 - Structural and chemical modifications of natural vermiculite samples induced by the treatment with Al(urea)63+ and Cr(urea)63+ complexes [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Dilillo, M.; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2003 - The crystal structure of Roscoelite-1M [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Caprilli, Enrico; Marchesini, M; Poppi, Luciano
abstract

2003 - The crystal structure of roscoelite-1M [Articolo su rivista]
Brigatti, Maria Franca; E., Caprilli; M., Marchesini; Poppi, Luciano
abstract

Single-crystal X-ray diffraction experiments were carried out on roscoelite crystals from Reppia, Val Graveglia, Italy. Roscoelite [structural formula: (XII)(Ba0.006K0.994)(IV)(Si3.150Al0.850) (VI)(Al0.040Fe0.150Mg0.100Mn0.062V1.696Ti0.003)O-10(OH)(2)] shows a near-perfect three-dimensional stacking order with cell parameters a = 5.292(1), b = 9.131(2), c = 10,206(3) Angstrom, beta = 100.98(2)degrees and space group C2/m, which indicate a 1M polytype. The crystal structure was refined on the basis of F-o(2) for 846 unique reflections to R1 = 3.29% calculated using 746 unique observed reflections [\F-o\ greater than or equal to 4sigma(F-o)]. The mean tetrahedral cation-oxygen atom distance, <T-O> = 1.641 Angstrom, is close to the mean <T-O> value obtained for dioctahedral true micas from the literature, whereas the octahedral sheet is characterized by a larger cis-octahedral cation-oxygen atom bond distance <M2-O> = 2.020 Angstrom which, together with the mean electron count, is consistent with V occupancy. The presence of V within the octahedral sheet produces the smallest tetrahedral rotation (alpha = 2.3degrees), the lowest flattening of the basal oxygen surface (Deltaz = 0.118 Angstrom) and the narrowest interlayer separation (3.030 Angstrom) in dioctahedral micas.

2003 - Ti-rich trioctahedral micas: similarities and dissimilarities in coexisting 1M and 2M1 polytypes [Relazione in Atti di Convegno]
Schingaro, E.; Scordari, F.; Brigatti, Maria Franca
abstract

2003 - X-Ray Absorption Spectroscopy: a Powerful Method to Investigate Structural and Electronic Properties of Layered Silicates [Relazione in Atti di Convegno]
Marcelli, A.; Mottana, A.; Cibin, G.; Cardelli, A.; Brigatti, Maria Franca
abstract

2002 - Characterization of Cu-complexes in smectite with different layer charge location: chemical, thermal and EXAFS study [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2002 - Crystal chemical study by XANES of trioctahedral micas: the most characteristic layer silicates [Articolo su rivista]
F., Tombolini; Brigatti, Maria Franca; A., Marcelli; G., Cibin; A., Mottana; G., Giuli
abstract

A crystal-chemical study of trioctahedral micas previously characterized by single-crystal XRD has been performed by XANES spectroscopy at the Si and Al K edges. XANES, being a local structural probe, can investigate distortion and modification of the tetrahedral sheet with increasing Fe for Mg substitution in the octahedral sheet. Comparison of XANES spectra allows determining the size of the tetrahedral site occupied by either Si or Al. The Si-O distance remains essentially unchanged whereas the Al-O distance appears to increase. The behavior may be interpreted as a tilt of the tetrahedra, initially rotated to match the ideal mica geometry, with increasing Fe substitution in the octahedral sheet.

2002 - Crystal chemistry of 1M mica polytype: the octahedral sheet [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Guggenheim, S.; Poppi, M.
abstract

2002 - Effect of composition on site, sheet and layer distortion of micas [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Guggenheim, S.
abstract

2002 - Effect of ionic solutions on clay minerals crystal chemistry. [Capitolo/Saggio]
Brigatti, Maria Franca; Medici, Luca; Poppi, Luciano
abstract

This work describes the basic structural features, the origin and properties of clay minerals and of interstratified clays in order to outline the kinetics of structural changes induced by clay-water and clay- ionic solutions interactions. The role of layer charge is discussed because it is recognized as one of the most important features of 2:1 phyllosilicates that produce the mineral ability to retain cations and to adsorb water and various polar molecules. Sample preparation techniques in order to obtain a representative clay-mineral for structural X-ray analysis, such as chemical pre-treatment and preparation of oriented clay mineral aggregates was also considered. A special focus was devoted to water-bearing clay minerals. In 2:1 layer and in 1:1 structures water occurs in interlayer positions and forms complexes with interlayer cations which are affected by P-T and chemical environmental conditions. Some examples of polluted environment remediation were reported in order to enhance clay mineral properties as barrier in environmental pollution.

2002 - Hg-Cysteine complexes in montmorillonite interlayer [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2002 - Local and average Fe distribution in trioctahedral micas: analysis of Fe K edge spectra in the phlogopite-annite and phlogopite-tetraferriphlogopite joins on the basis of single-crystal XRD drefinements. [Articolo su rivista]
F., Tombolini; Brigatti, Maria Franca; A., Marcelli; G., Cibin; A., Mottana; G., Giuli
abstract

In Fe-bearing trioctahedral 1M micas Fe2+ occurs essentially in the octahedral O sheet whereas Fe3+ either coexists with Fe2+ in the octahedral M sites or, more rarely, enters the tetrahedral T sites. The Fe K-edge absorption spectra of twelve micas were recorded in an effort to relate the observed multiple-scattering absorption features to the results of single-crystal X-ray structure refinements obtained on crystals from the same rock sample. This study first addresses the three end-members phlogopite, annite and tetra-ferriphlogopite, used as reference materials, and enters later in the interpretation of nine trioctahedral micas intermediate in composition along the joins phlogopite-tetra-ferriphlogopite and phlogopite-annite. A detailed analysis of the observed XANES features singles out the independent effects of coordination and valence, and shows distinctly different position vs. intensity trends that depend upon the local Fe2+ and Fe3+ environments. Bond distances evaluated from XANES spectra in the full multiple-scattering region of the K-edge spectrum agree well with those obtained by XRD refinement. Distinct variations in the local to intermediate degrees of order of certain micas can be determined by the analysis of their intermediate multiple-scattering regions; they supplement the information on their long-range order that is best obtained through the XRD refinement.

2002 - Metal-organic Cu complexes in smectites with different layer charge location: chemical, thermal and EXAFS study [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Colonna, S.; Malferrari, Daniele; Medici, L.
abstract

2002 - Mica Crystal Chemistry and the Influence of Pressure, Temperature, and Solid Solution on Atomistic Models [Capitolo/Saggio]
Brigatti, Maria Franca; Guggenheim, S.
abstract

The editors and contributing authors of this volume participated in a short course on micas in Rome late in the year 2000. It was organised by Prof. Annibale Mottana and several colleagues (details in the Preface below) and underwritten by the Italian National Academy, Accademia Nationale dei Lincei (ANL). The Academy subsequently joined with the Mineralogical Society of America (MSA) in publishing this volume. MSA is grateful for their generous involvement.Micas are among the most common minerals in the Earth crust: 4.5% by volume. They are widespread in most if not all metamorphic rocks (abundance: 11 %), and common also in sediments and sedimentary and igneous rocks. Characteristically, micas form in the uppermost greenschist facies and remain stable to the lower crust, including anatectic rocks (the only exception: granulite facies racks). Moreover, some micas are stable in sediments and diagenetic rocks and crystallize in many types of lavas. In contrast, they are also present in association with minerals originating from the very deepest parts of the mantle-they are the most common minerals accompanying diamond in kimberlites.The number of research papers dedicated to micas is enormous, but knowledge of them is limited and not as extensive as that of other rock-forming minerals, for reasons mostly relating to their complex layer texture that makes obtaining crystals suitable for careful studies with modern methods time-consuming, painstaking work.Micas were reviewed extensively in 1984 (Reviews in Mineralogy 13, S.W. Bailey, editor). At that time, the "Micas" volume covered most if not all aspects of mica knowledge, thus producing a long shelf-life for this book. Yet, or perhaps because of that excellent review, mica research was vigorously renewed, and a vast array of new data has been gathered over the past 15 years. These data now need to be organized and reviewed. Furthermore, a Committee nominated by the International Mineralogical Association in the late 1970s concluded its long-lasting work (Rieder et al. 1998) by suggesting a new classification scheme which has stimulated new chemical and structural research on micas. To make a very long story short: the extraordinarily large, but intrinsically vague, mica nomenclature developed during the past two centuries has been reduced from >300 to just 37 species names and 6 series (see page xiii, preceding Chapter 1); the new nomenclature shows wide gaps that require data involving new chemical and structural work; the suggestion of using adjectival modifiers for those varieties that deviate away from end-member compositions requires the need for new and accurate measurements, particularly for certain light elements and volatiles; the use of polytype suffixes based on the modified Gard symbolism created better ways of determining precise stacking sequences. This resulted in new polytypes being discovered.Indeed, all this has happened over the past few years in an almost tumultuous way.It was on the basis of these developments that four scientists (B. Zanettin, A. Mottana, F.P. Sassi and C. Cipriani) applied to Accademia Nazionale dei Lincei-the Italian National Academy-for a meeting on micas. An international meeting was convened in Rome on November 2-3, 2000 with the title Advances on Micas (Problems, Methods, Applications in Geodynamics). The topics of this meeting were the crystalchemical, petrological, and historical aspects of the micas. The organizers were both Academy members (C. Cipriani, A. Mottana, F.P. Sassi, W. Schreyer, lB. Thompson Jr., and B. Zanettin) and Italian scientists well-known for their studies on layer silicates (Professors M.F. Brigatti and G. Ferraris). Financial support in additional to that by the Academy was provided by C.N.R. (the Italian National Research Council), M.U.R.S.T. (the Italian Ministry for University, Scientific Research and Technology) and the University of Rome III. Approximately 200 scientists attended the meet

2002 - Raw natural materials for conventional ceramics [Relazione in Atti di Convegno]
Brigatti, Maria Franca
abstract

non disponibile

2002 - Reactions between Cr(VI) solutions and pyrite: chemical and surface studies [Articolo su rivista]
Benincasa, E.; Brigatti, Maria Franca; Franchini, Giancarlo; Malferrari, Daniele; Medici, L.; Poppi, Luciano; Tonelli, Massimo
abstract

Geochemical processes that result in the reduction of hexavalent chromium in natural waters with pyrite (FeS2) have been studied at varying degrees of pH (from 1.2 to 12.6) and solution concentration (from 0.001 to 0.3 M of Cr6+) in order to illustrate the differences in the proportions of elements between the aqueous and solid phases and to infer mechanisms that limit the Cr6+ concentration in pore-waters in iron sulfide-rich environments. The experiments were carried out in the absence of oxygen and on pyrite grains previously treated to remove any oxide or sulfur layer at the mineral surface. The methods used to characterize reacting solutions and mineral surface comprised: chemical analyses (microprobe analyses and inductively coupled plasma analyses), scanning electron microscopy, atomic force microscopy and X-ray single crystal analysis. The results suggest that: 1) mineral dissolution increases with decreasing pH, whereas it is close to zero at pH > 7; at alkaline pH, the Cr6+ reduction is very low and the decrease in total Cr probably indicates the formation of precipitated phases, like FeCrO4, on the pyrite surface; 2) Cr6+ reduction is significant at pH < 2.3. Cr6+ to Cr3+ reduction involves the oxidation of Fe2+ and S22- on the pyrite surfaces, following the reaction 2FeS2+5Cr2O72-+32H+2Fe(OH)3 +4(SO4)2- +10Cr3+ +13H2O; 3) at acidic pH all the pyrite crystals show a variable Cr content on the surfaces.

2002 - Reactions of Zn2+ aqueous solutions with fluor-hydroxyapatite: a crystallographic evidence [Articolo su rivista]
Brigatti, Maria Franca; Benincasa, Emanuele; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

In order to evaluate the possible use of natural fluor-hydroxyapatite (FOHAp) crystals as soil additive for the in situ remediation of heavy-metal contaminated soils, the crystal structure of FOHAp crystals, used in batch experiments at 22°C with pH within the range 4.8-9.5 and in presence of Zn2+ ions, was determined. Crystal structures (space group P63/m) converged to R = 0.026 for untreated FOHAp and to R =0.028 (Experiment 1) and R= 0.032 (Experiment 2) for Zn2+-treated FOHAp crystals. The site occupancy ratios [(Zn-Ca)2/(Zn-Ca)1] obtained from the refinement of electron density is = 1.500 for natural FOHAp, 1.500 (Experiment 1) and 1.520 (Experiment 2) in Zn2+-treated crystals. The value deriving from experiment 2 agrees with small changes in Ca2 site occupancy. Ca2O6X polyhedron distortions may be related both to a slight preference of Zn for Ca2 and to OH for F substitution during the overall reaction sequence.

2002 - Report of the Association Internationale pour l'Etude des Argiles (AIPEA) Nomenclature Committee for 2001: order, disorder and crystallinity in phyllosilicates and the use of the 'Crystallinity Index' [Articolo su rivista]
S., Guggenheim; D. C., Bain; F., Bergaya; Brigatti, Maria Franca; V. A., Drits; D. D., Eberl; M. L., Formoso; E., Galan; R. J., Merriman; D. R., Peacor; H., Stanjek; T., Watanabe
abstract

The purpose of this report is to describe the appropriate use of indices relating to crystallinity, such as the ‘crystallinity index’, the ‘Hinckley index’, the ‘Kübler index’, and the ‘Árkai index’. A ‘crystalline’ solid is defined as a solid consisting of atoms, ions or molecules packed together in a periodic arrangement. A ‘crystallinity index’ is purported to be a measure of crystallinity, although there is uncertainty about what this means (see below). This report discusses briefly the nature of order, disorder and crystallinity in phyllo-silicates and discusses why the use of a ‘crystallinity index’ should be avoided. If possible, it is suggested that indices be referred to using the name of the author who originally described the parameter, e.g.‘Hinckley index’ or ‘Kübler index’, or in honor of a researcher who investigated the importance of the parameter extensively, e.g. ‘Árkai index’.In contrast to a crystalline solid, an ‘amorphous’ solid is one in which the constituent components are arranged randomly. However, many variations occur between the two extremes of crystalline vs. amorphous. For example, one type of amorphous material might consist simply of atoms showing no order and no periodicity. Alternatively, another amorphous material may consist of atoms arranged, for example, as groups of tetrahedra (i.e. limited order) with each group displaced or rotated (e.g. without periodicity) relative to another. Thus, this latter material is nearly entirely amorphous, but differs from the first. Likewise, disturbance of order and periodicity may occur in crystalline materials. The terms ‘order’ and ‘disorder’ refer to the collective nature or degree of such disturbances. Although seemingly simple notions, ‘crystalline’ and ‘amorphous’ are complex concepts.Crystalline substances may show a periodic internal structure based on direction. For example, two-dimensional periodicity is common in phyllosilicates where two adjacent sheets or layers must mesh. For example, in serpentine, …

2002 - Sorption of Cd-cysteine complexes by kaolinite [Articolo su rivista]
Benincasa, Emanuele; Brigatti, Maria Franca; Malferrari, Daniele; L., Medici; Poppi, Luciano
abstract

The effect of cysteine on the adsorption of Cd(II) by kaolinite was examined at 25 jC using a low-defect kaolinite fromMinas Gerais (Brazil) and a high-defect kaolinite from Berici Hills (Italy). The chemical data demonstrated that the amount ofCd–cysteine detected on kaolinite increases rapidly during the first few hours with a first-order reaction, thereafter adsorptionbecomes linear with time for low-defect kaolinite and slows rapidly for high-defect kaolinite. In low-ordered kaolinite, the Cd–cysteine is intercalated in the structure. Evidence of these changes was also observed by differential thermal analysis (DTA).The thermal decomposition of the Cd–cysteine adsorbed on the kaolinites was studied by analysing the evolved gases. Themass spectra of both samples show the evolution of NO (or CH3CH3, m/z = 30), CO2 (m/z = 44), and SO2 (m/z = 64) between 150 and 300 jC and of H2O (m/z = 18), CO2 (m/z = 44) and SO2 (m/z = 64) in the temperature range between 400 and 700 jC.The high-defect kaolinite also caused the evolution of molecular units with m/z=34 (H2S) and m/z=76 (N2O3). D 2002Elsevier Science B.V. All rights reserved.

2002 - Structural modifications induced by metal complexation with organic matter in smectites: a multi-analytical approach [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Colonna, S.; Malferrari, Daniele; Medici, L.
abstract

2001 - Associate editor of American Mineralogist from 2001 to 2005 [Direzione o Responsabilità Riviste]
Brigatti, Maria Franca
abstract

2001 - Chromium-containing muscovite: crystal chemistry and XANES Spectroscopy [Articolo su rivista]
Brigatti, Maria Franca; Galli, Ermanno; L., Medici; Poppi, Luciano; G., Cibin; A., Marcelli; A., Mottana
abstract

To verify chromium enrichment of the muscovite layer, a crystal chemical and XANES study on chromium-containing muscovite crystals from the South Island of New Zealand was carried out. The crystals studied differ from those of end-member muscovite in that they display variable levels of octahedral substitutions and homovalent and heterovalent substitution of K in interlayer sites. Single-crystal X-ray diffraction data were collected for three crystals in the space group C2/c to an agreement factor (Robs) from 0.025 to 0.033. Tetrahedral cation disorder was found for each sample and the values of <T-O> mean bond length for both tetrahedra do not depart significantly from that of the end-member muscovite-2M1. Electron density at the M2 site is greater than that required for the ideal muscovite-2M1 structure, and a small excess of electron density is found for two crystals in M1. As the octahedral substitution of larger cations for Al increases in the octahedral sites, the match between tetrahedral and octahedral sheets improves and tetrahedral rotation angle, [ , decreases. XANES spectra at the Cr K-edge in these chromium-containing muscovite samples exhibit octahedral symmetry. Moreover, a careful analysis of the pre-edge region shows at least two features. A qualitative fitting procedure of the pre-edge region indicates that no more than 0.5% of total Cr(III), if any, may occupy the tetrahedral site.

2001 - Crystal chemistry of phlogopite-1M and tetra-ferriphlogopite-1M from Alto Paranaíba igneous province (south-east Brazil) [Relazione in Atti di Convegno]
Brigatti, Maria Franca; L., Medici; Poppi, Luciano; C., Vaccaro
abstract

2001 - Crystal chemistry of trioctahedral micas-1M from Alto Paranaíba Igneous Province, South-Eastern Brazil. [Articolo su rivista]
Brigatti, Maria Franca; Medici, L.; Poppi, Luciano; Vaccaro, C.
abstract

The crystal structures of nine trioctahedral mica-1M crystals (phlogopite and ferroan phlogopite containing Fe3+ in tetrahedral position, ferroan tetra-ferriphlogopite, and titanian phlogopite), from ultramafic alkaline-silicate lavas and alkaline-silicate, silicate-carbonatite and carbonatite plutonic rocks occurring in the Alto Paranaíba Igneous Province (southeastern Brazil), were refined from single-crystal X-ray data in the space group C2/m to R values between 0.025 and 0.039. These mica crystals are characterized by low to very low Al content; therefore, Fe3+ may be essential to fill the tetrahedral site. The octahedral position of all the crystals studied is characterized by variable amounts of Fe2+, Fe3+ and Ti4+ in substitution for Mg. The two independent octahedral sites, M1 and M2, show equivalent mean electron-density and mean bond-distances in most cases. Order at the octahedral sites is enhanced in the Ti-rich crystal from Presidente Olegario owing to the preference of Ti for the M2 site. The lateral parameters a and b reflect variations in tetrahedron composition, whereas the periodicity along c depends on octahedron composition. The crystal-chemical features of these micas are controlled by the peculiar composition of the rocks, by the high f(O2), a(H2O), and f(CO2), and by metasomatic events that have affected the Alto Paranaíba Igneous Province.

2001 - Crystal structure and crystal chemistry of lithium-bearing muscovite-2M(1) [Articolo su rivista]
Brigatti, Maria Franca; D. E., Kile; Poppi, Marco
abstract

Crystal-structure refinements were done on Li-bearing muscovite-2M(l) crystals from microgranite and granitic pegmatite rocks in order to characterize their crystal chemistry and their relationships with muscovite and trioctahedral lithium-containing micas. In addition to the substitution mechanism Li-[6](+) Al-[6](-1)3+ Al-[4](-2)3+ Si-[4](2)4+, Li-bearing muscovite shows additional substitutions, such as mechanism Li-[6](+) Fe-[6](2+) Al-[6](-1)3+ ([6])(square -1), indicating that the structure deviates from ideal dioctahedral character. Single-crystal X-ray-diffraction data were collected for five crystals in space group C2/c; the agreement factor, R-obs, varies between 0.033 and 0.042. The mean tetrahedral cation-oxygen atom distances range from 1.637 to 1.646 Angstrom and from 1.629 to 1.647 Angstrom for T1 and T2 sites, respectively. Variation in <T-O > distances is associated with the Li+ / (Li+ + Al3+) ratio, octahedral M2 site expansion (9.30 less than or equal to volume(M2) less than or equal to 9.90 Angstrom (3)) and reduction in size of the M1 site. Moreover, as the Li+ / (Li+ + Al3+) ratio increases, the silicate ring becomes less distorted (5.9 less than or equal to alpha less than or equal to 11.4 degrees), the basal oxygen-atom planes become less corrugated (0.147 less than or equal to Deltaz less than or equal to 0.232 Angstrom), and the interlayer separation narrows (3.337 less than or equal to interlayer separation less than or equal to 3.422 Angstrom).

2001 - Effect of ionic solutions on clay minerals crystal chemistry [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Medici, L.; Poppi, Luciano
abstract

2001 - Environmental protection and phyllosilicates [Articolo su rivista]
Brigatti, Maria Franca; L., Medici; Poppi, Luciano
abstract

2001 - Experimental and theoretical XANES and EXAFS study of tetra-ferriphlogopite [Articolo su rivista]
G., Giuli; E., Paris; Z. Y., Wu; Brigatti, Maria Franca; G., Cibin; A., Mottana; A., Marcelli
abstract

Experimental and theoretical EXAFS and XANES data on Fe coordination and bond distances have been obtained for a natural tetra-ferriphlogopite. XANES data show a predominance of trivalent iron in tetrahedral coordination. The use of theoretical multiple scattering calculations helps distinguish the contributions to the total spectrum coming from the different iron atoms. EXAFS spectra were reduced and analyzed using the GNXAS programs and Fe has been confirmed to be in tetrahedral coordination, with refined structural data Fe-O = 1.86 Angstrom, Fe-Si = 3.24 Angstrom, Fe-O-Si = 138 degrees. Moreover, a further contribution from Fe is detected corresponding to a Fe-O distance equal to 2.22 Angstrom. This latter contribution (20 mol % of the total Fe ca.) is interpreted to arise from divalent Fe in octahedral coordination, in excellent agreement with the structural and chemical data.

2001 - K-rich rectorite from kaolinized micaschits of Sesia-Lanzo Zone (Italy) [Articolo su rivista]
Benincasa, Emanuele; Brigatti, Maria Franca; Medici, L.; Poppi, Luciano
abstract

Rectorite crystals [[4](Si6.81Al1.19)[6](Al3.26Ti0.04Fe0.553+Mg0.18Mn0.01)[12](Na0.02K0.88Mg0.16Ca0.01)O20(OH)4·0.75H2O] found in mica schists of the Sesia-Lanzo Zone (NW Italy) were studied using a variety of techniques including microprobe anal., IR spectroscopy, single crystal and powder X-ray diffraction, at. force microscopy, and thermal anal. Chem. data and exchangeable cation detn. indicate that K+ is the dominant non-exchangeable interlayer cation, and thus is believed to occupy the mica interlayer site; Mg2+ together with small amts. of Ca2+, Na+ and K+ represent the exchangeable cations and can therefore be related to the smectite-like component. The coeff. of variation (CV) of d(00l) values (CVnatural = 0.47; CVglycolated = 0.43) demonstrates the regularity of the mica-smectite interstratification, whereas the unit-cell parameters obtained by single crystal methods suggest different layer-stacking models.

2001 - Kinetics of Cd sorption by kaolinite in presence of sulphur-bearing amino acids [Relazione in Atti di Convegno]
Benincasa, Emanuele; Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2001 - Kinetics of Cr(VI) reduction by Fe(II)-bearing minerals: chemical treatments, X-ray absorption spectroscopy and surface studies. [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Benincasa, Emanuele; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2001 - Mica crystal chemistry and the influence octahedral solid solution on atomistic models [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Poppi, M.
abstract

2001 - Reactions of Hg ions in aqueous solutions with smectite in presence of the amino acid cysteine [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Malferrari, Daniele; Poppi, Luciano
abstract

2001 - Reactions of Pb2+ and Zn2+ aqueous solutions with fluorapatite crystals [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Benincasa, Emanuele; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2001 - Structural and chemical modifications of natural vermiculite samples induced by the treatment with Cd-ethylenediamine complex [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Benincasa, Emanuele; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2001 - Structural and chemical modifications of vermiculite crystals induced by Cd-ethylenediamine complex treatment [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Benincasa, Emanuele; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2001 - X-ray absorption spectroscopy of Cu-rich smectites treated with alpha-amino acids [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Benincasa, Emanuele; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2000 - A regular interstratified mica-smectite mineral from micaschist levels of Sesia Lanzo Zone (Italy) [Relazione in Atti di Convegno]
Benincasa, Emanuele; Brigatti, Maria Franca; Malferrari, Daniele; M. e. d. i. c. i., L.; Poppi, Luciano
abstract

2000 - Analisi termiche [Capitolo/Saggio]
Brigatti, Maria Franca
abstract

non disponibile

2000 - Crystal chemical studies and recent trends in the research into clay minerals [Abstract in Rivista]
Brigatti, Maria Franca
abstract

2000 - Crystal chemical variations in Li- and Fe-rich micas from Pikes Peak batholith (central Colorado) [Articolo su rivista]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, Luciano; E. E., Foord; D. E., Kile
abstract

The crystal structure and M-site populations of a series of micas-1M from miarolitic pegmatites that formed within host granitic rocks of the Precambrian, anorogenic Pikes Peak batholith, central Colorado, were determined by single-crystal X-ray diffraction data. Crystals fall in the polylithionite-siderophyllite-annite field, being 0 less than or equal to Li less than or equal to 2.82, 0.90 less than or equal to Fe-total less than or equal to 5.00, 0.26 less than or equal to([6])Al less than or equal to 2.23 apfu. Ordering of trivalent cations (mainly Al3+) is revealed in a cis-octahedral site (M2 or M3), which leads to a lowering of the layer symmetry from C12/m(1) (siderophyllite and annite crystals) to C12(1) diperiodic group (lithian siderophyllite and ferroan polylithionite crystals). On the basis of mean bond length the ordering scheme of octahedral cations is mostly meso-octahedral, whereas the mean electron count at each M site suggests both meso- and hetero-octahedral ordering, the calculated mean atomic numbers being M1 = M3 not equal M2, M2 = M3 not equal M1 and M1 not equal M2 not equal M3. As the siderophyllite content increases, so do the a, b, and c unit-cell parameters, as well as the refractive indices, primarily np. The tetrahedral rotation angle, alpha, is generally small (1.51 less than or equal to alpha less than or equal to 5.04 degrees) and roughly increases with polylithionite content, whereas the basal oxygen out-of-plane tilting, Delta z, is sensitive both to octahedral composition and degree of order (0.0 less than or equal to Delta z less than or equal to 0.009 Angstrom for siderophyllite and annite, 0.058 less than or equal to Delta z less than or equal to 0.144 Angstrom for lithian siderophyllite and ferroan polylithionite crystals).

2000 - Crystal chemistry of Al-rich biotites coexisting with muscovites in peraluminous granites [Articolo su rivista]
Brigatti, Maria Franca; P., Frigieri; C., Ghezzo; Poppi, Luciano
abstract

A comparison was made between single-crystal structure refinements, electron microprobe analy ses and octahedral site populations of seven biotite crystals and data obtained previously for coexisting muscovite in peraluminous granites using the same methods. Both micas, From several plutons of Northern Victoria Land (Antarctica) and Sardinia (Italy), show significant octahedral substitutions: biotite has a composition characterized by relatively high Al-[6] content (0.32 less than or equal to Al-[6] less than or equal to 0.59 apfu), whereas muscovite is characterized by phengite-like substitutions [0.12 less than or equal to ([6])(Mg + Fe + Ti + Mn) less than or equal to 0.35]. Mean bond-lengths and electron count data for six biotites-1M (space group C2/m. agreement factor 2.7% less than or equal to R-obs less than or equal to 3.6%) and a biotite-2M(1) (space group C2/c, R-obs = 2.8%) show that Al substitutes for divalent cations in the octahedral M2 site and that the Fe and Mg distribution is disordered. The mean tetrahedral bond lengths determined for biotite-2M(1) reflect Al-Si disorder. In coexisting muscovite-2M(1) crystals, small positive electron density residuals close to M1 site position as well as the increase in M2 mean atomic number is in agreement with the presence of a significant phengitic component. Reduction in biotite unit-cell dimensions with the increase of Al follows a pattern similar to that of associated muscovites. and the octahedral site volumes of both micas are influenced by the Al saturation index (ASI) of the rock. These results, and the calculated partition coefficients between biotite and muscovite for elements in M sites, are consistent with continuous reaction and re-equilibration of biotite and muscovite during crystallization of peraluminous granitic melts.

2000 - Crystal chemistry of magnesian annite and ferroan phlogopite crystals from metapelites [Abstract in Rivista]
Benincasa, Emanuele; Brigatti, Maria Franca; Guidotti, C. V.; Poppi, Luciano
abstract

2000 - Crystal structure and chemistry of chromium-containing muscovite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Galli, Ermanno; Medici, L.; Poppi, Luciano; Cibin, G. T.; Marcelli, A.; Mottana, A.
abstract

2000 - Experimental evidence of Hg and Cu retention by montmorillonite: a combined chemical and XAS study [Abstract in Rivista]
Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2000 - Heavy metals in polluted soils: kinetics of migration [Relazione in Atti di Convegno]
Brigatti, Maria Franca
abstract

2000 - Interaction between aqueous chromium solutions and layer silicates [Articolo su rivista]
Brigatti, Maria Franca; Franchini, Giancarlo; Lugli, Cristina; L., Medici; Poppi, Luciano; E., Turci
abstract

The interactions between Cr in aqueous solutions and phyllosilicates were studied to determine: (a) the amount of Cr(VI) to Cr(III) reduction in aqueous solutions by Fe(II)-bearing phyllosilicates; (b) the removal of the Cr species from solution by interaction with phyllosilicates, as a function of Cr(III) concentration and anionic environment. Chlorite, corrensite and montmorillonite were reacted with solutions containing Cr(VI) (1.62 x 10(-3) N, 5.77 x 10-3 N and 1.32 x 10(-1) N, respectively). The sorption/desorption of Cr(III) by saponite was investigated in different anionic environments (Cl-, NO3- and CH3COO-) and at different initial Cr(III) concentrations (3.21 x 10(-3) N, 5.49 x 10(-3) N and 8.49 x 10(-3) N). The extent of Cr(VI) reduction and the amount of Cr removed by phyllosilicates were measured by analysis of the liquid portion separated by centrifugation after controled periods of exposure. The minerals were studied by chemical, thermal and X-ray powder diffraction analyses. The results show that: (i) Fe(II)-bearing phyllosilicates sorb Cr and reduce Cr(VI) to Cr(III); (ii) the extent of reduction depends on the solution concentration and on mineral crystal chemistry; (iii) Cr(III) sorption isotherms show that the degree of uptake depends both on the initial concentration of metal in solution and on the anionic environment, the order of effectiveness being Cl- congruent to NO3- > CH3COO-; (iii) Cr(III) is retained in the mineral substrate and its release is difficult. (C) 2000 Elsevier Science Ltd. All rights reserved.

2000 - Interaction between glycine and Na-, Ca- and Cu-rich smectites [Articolo su rivista]
Benincasa, Emanuele; Brigatti, Maria Franca; Lugli, Cristina; L., Medici; Poppi, Luciano
abstract

The interactions between glycine and two Na-, Ca- and Cu-exchanged smectites with different layer-charge location were studied. The sorption of glycine depends on the nature of the interlayer cations (Ca < Na < Cu), and on the type of smectite. Sequential extraction procedures were carried out in order to test the possibility of removing metals and/or glycine from the smectite interlayer. By the end of the treatments, the release of the amino acid from the substrates, with the exception of Cu-rich smectite, was virtually complete. The thermal curves of glycine-smectites confirm the stronger bonding of the amino acid with Cu-exchanged samples, and FTIR spectra indicate that glycine is mainly sorbed in the zwittterionic form. The data obtained suggest that in investigations into mechanisms of the binding of metals by minerals and their subsequent mobilization, amino acids merit close attention.

2000 - Interaction of pyrite surface with Cr(VI) aqueous solutions [Abstract in Rivista]
Benincasa, Emanuele; Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Poppi, Luciano; Vendrame, F.
abstract

2000 - Iron local environment in a natural ferriphlogopite by Fe K-edge XAS [Relazione in Atti di Convegno]
Paris, E.; Giuli, G.; Brigatti, Maria Franca; Marcelli, A.; Mottana, A.; Wu, Z.
abstract

2000 - K-rich rectorite from kaolinized micaschists of Sesia-Lanzo zone (Italy) [Abstract in Rivista]
Benincasa, Emanuele; Brigatti, Maria Franca; Malferrari, Daniele; Medici, L.; Poppi, Luciano
abstract

2000 - Kinetics of heavy-metal removal and recovery in sepiolite [Articolo su rivista]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, Luciano
abstract

Fixed beds of Mg-enriched sepiolite were percolated through Co2+, Cu2+, Zn2+, Cd2+ and Pb2+ single- and multicomponent heavy-metal solutions to study both the dynamic interactions between mineral and heavy-metal cations and the ion-sorption kinetics. The metal concentrations in the eluates were determined by atomic adsorption and/or inductively-coupled plasma and kinetics by the classical kinetic approach, using isothermal experiments at room temperature. The experimental results suggest that: (i) the amount of heavy metal sorbed by the mineral increases for smaller cations; ii) the sepiolite sorption efficiency sequence is, for single component solution, Pb2+ < Cd2+ < Co2+ < Zn2+ < Cu2+, and; for multicomponent solution, Pb2+ = Co2+ < Cd2+ < Zn2+ < Cu2+. Therefore, the ability of sepiolite to remove Cu2+, Zn2+, Cd2+ and Pb2+ is virtually independent of the competitive cation interactions, whereas its affinity for Co2+ is lower when other metals coexist in the solution. The cationic sorption-exchange equilibrium constants (k), obtained by fitting the data with Langmuir equations are: k(Co)(2+) = 4.798 x 10(-3), k(Cu)(2+) = 3.424 x 10(-3) k(Zn)(2-) = 2.907 x 10(-3), k(Pb)(2+) = 1.009 X 10(-2) [meq min](-1), k(Cd)(2+) = 1.187 X 10(-2) [meq min](-1/2) for monocomponent solution experiment. The desorption study concerning the nature of eluting agents shows that Mg2+ is more effective than Na+ in removing heavy metals. Rapid kinetics and equilibrium of exchange of Mg2+ for heavy metals were observed; this is thought to indicate that the main process occurs at easily accessible sites at the outer and channel surface. Moreover, other processes can be assigned to the exchange of Mg2+ in the octahedral sites at the channel edges. (C) 2000 Elsevier Science B.V. All rights reserved.

2000 - Magnesian annite and ferroan phlogopite crystals from metapelites of western Maine: a crustal chemical study [Relazione in Atti di Convegno]
Benincasa, Emanuele; Brigatti, Maria Franca; Guidotti, C.; Poppi, Luciano
abstract

2000 - Mean and local ordering of Cr in muscovite: A single crystal XRD and XAS study [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Galli, Ermanno; Medici, L.; Poppi, Luciano; Cibin, G.; Marcelli, A.; Mottana, A.
abstract

2000 - Mica crystal chemistry and the influence of intensive variables on atomistic models [Capitolo/Saggio]
Brigatti, Maria Franca; Guggenheim, S.
abstract

Tavola rotonda nell'ambito della Conferenza annuale della Ricerca.

2000 - Reduction and sorption of chromium by Fe(II)-bearing phyllosilicates: chemical treatments and X-ray absorption spectroscopy (XAS) studies [Articolo su rivista]
Brigatti, Maria Franca; Lugli, Cristina; G., Cibin; A., Marcelli; G., Giuli; E., Paris; A., Mottana; Z. Y., Wu
abstract

The reduction of hexavalent chromium species in aqueous solutions by interaction with Fe(II)-bearing solid surfaces was studied using a 0.96 x 10(-3)M Cr(VI) solution and iron-rich clays with different Fe(II)/Fe(III) ratios, layer charge, and exchange properties, i.e., chlorite, corrensite, and montmorillonite. Experimental studies demonstrated that Fe(II)-bearing phyllosilicates reduce aqueous Cr(VI) ions at acidic pH. Chlorite and corrensite, owing to the high Fe(II)/Fe(III) ratio, are electrochemically reactive, as rapid Cr(VI) reduction indicated. In contrast, montmorillonite showed minimum to nil reactivity towards Cr(VI). Furthermore, corrensite, which is high in both Fe(II)/Fe(III) ratio and exchange capacity, adsorbs the greatest amount of chromium. X-ray absorption spectroscopy at Al, Mg, Fe, and Cr K-edges was used to investigate the adsorbed chromium species. The montmorillonite sample, unaffected by treatment with Cr(VI) solution, displays no change at any investigated edge. Edge shape and energy also do not change for the Mg and Al spectra in corrensite, and changes are minor in chlorite. By contrast, the Fe K-edge changes both in chlorite and corrensite, and indicates an increase of Fe(III) in treated samples at the expense of pre-existing Fe(II). Cr K-edge spectra show that chlorite and corrensite sorb Cr(III), which implies its reduction from Cr(VI) in the interacting solution.

2000 - XAFS study of Cu sorption products on smectites treated with alpha-amino acids [Relazione in Atti di Convegno]
Benincasa, Emanuele; Brigatti, Maria Franca; Malferrari, Daniele; Poppi, Luciano
abstract

The interaction between Cu-exchanged smectites with different layer charge, a montmorillonite and a beidellite, and .alpha.-amino acids, glycine and cysteine, was studied. Sequential extn. procedures were carried out in order to test the possibility of removing metals from the mineral structure. Cu sorption is dominated by cation exchange, whereas after the amino acid treatment, Cu-amino acid-smectite complexes occupy the interlayer positions. The formation of a stable chelate complex with .alpha.-amino acids permits Cu to be resistant to migration in soils and groundwaters. X-ray absorption spectroscopy was used to define the local environment of Cu taken up by smectites.

1999 - Adsorption of Cd(II)-cysteine complexes by kaolinite [Abstract in Rivista]
Benincasa, Emanuele; Brigatti, Maria Franca; R., Ciancio; Lugli, Cristina; L., Medici; Poppi, Luciano
abstract

1999 - Adsorption of metal-cysteine complexes on kaolinite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, Cristina; L., Medici; Poppi, Luciano; Benincasa, Emanuele; R., Ciancio
abstract

1999 - Associate editor of Clay Minerals from 1999 until now [Direzione o Responsabilità Riviste]
Brigatti, Maria Franca
abstract

1999 - Crystal chemistry of [4]Fe3+-rich phlogopites: a combined single-crystal X-ray and Mössbauer study. [Capitolo/Saggio]
Brigatti, Maria Franca; A. E., Lalonde; L., Medici
abstract

An invaluable reference source for scientific and industrial research scientists, planners and administrators, particularly.

1999 - Crystal chemistry of lithian muscovite-2M1 [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, Luciano
abstract

1999 - Crystal chemistry of rectorite from a kaolinized micaschist formation (Castellamonte, Northwestern Italy) [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, Cristina; L., Medici; Poppi, Luciano; Benincasa, Emanuele
abstract

1999 - Crystal structure and chemistry of trioctahedral micas on the annite-siderophyllite-polylithionite system [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, Luciano
abstract

1999 - Crystal structure and chemistry of yuanfuliite and its relationships with warwickite [Articolo su rivista]
P. W. U., Appel; Bigi, Simona; Brigatti, Maria Franca
abstract

Yuanfuliite crystals, ideally MgFe3+O(BO3), i.e. the Fe3+ analogue of warwickite Mg1.5Ti0.5O(BO3), have been found in ultramafic rocks of Precambrian age in Inglefield Land (North-West Greenland). Structure refinements (space group Pnma) of two crystals with slightly different composition (agreement factors R = 0.023 and 0.025, respectively), have shown, in both cases, that the two octahedral M1 and M2 sites are geometrically quite similar but compositionally different, being Fe3+ strongly ordered at M1 and Al partially ordered at M2. The yuanfuliite cation ordering scheme has been compared with that of warwickite. Selected area electron diffraction patterns and high-resolution transmission electron microscopy images of yuanfuliite show a generally well-ordered structure. Some defects, confined to small crystal areas, are related to regularly distributed dislocations.

1999 - Effect of exchange cations and layer charge location on the sorption and retention of cysteine by smectites [Articolo su rivista]
Brigatti, Maria Franca; Lugli, Cristina; Montorsi, S.; Poppi, Luciano
abstract

This study investigates the complexes formed between amino acids, which are the natural degradation products of organic matter, and smectites. Thus, the adsorption and desorption behavior of cysteine and Na-, Ca-, Cu-homoionic smectites with different layer-charge location, a montmorillonite, and a beidellite, were studied. The clay samples were treated with Na, Ca, and Cu 1 N solutions and then with a 0.2 M cysteine solution. To test smectite-cysteine stability at acidic pH, the solids obtained were repeatedly treated with distilled water acidified to pH = 5. All treated samples were characterized by thermal, X-ray diffraction, chemical, and infrared analyses. The results showed that: 1) Na- and Ca rich smectites adsorbed and retained small amounts of cysteine, and did not show interlayer cation cysteine complexes, whereas the amino acid was strongly retained in the interlayer by Cu-rich smectites; 2) d(001)-values for Na- and Ca-rich smectites showed little or no expansion, whereas for the Cu-rich smectites the intercalation of the organic molecule produced a swelling of the structure; 3) the interaction mechanism of homoionic smectites with cysteine in an aqueous medium occurs by weak interactions, (e.g., van der Waals interactions, hydrogen bonding, dipole-dipole interactions, and other electrostatic forces such as entropy-driven hydrophobic bonding), and/or by complexes involving interlayer cations and organic ligands. The formation of a stable chelate complex with the saturating ion permits cysteine to be adsorbed by Cu(II)-rich smectites and to be resistant to migration in soils and groundwaters.

1999 - Fe2+-bearing layer silicates as a reductant of Cr6+ in aqueous solution [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, Cristina; L., Medici; Poppi, Luciano; Benincasa, Emanuele
abstract

1999 - Influence of layer charge on the adsorption and retention of clycine-metal complexes by smectites [Abstract in Rivista]
Benincasa, Emanuele; Brigatti, Maria Franca; Lugli, Cristina; L., Medici; Poppi, Luciano
abstract

1999 - Interaction between vermiculite and organic pollutants [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, Cristina; L., Medici; Poppi, Luciano; Benincasa, Emanuele
abstract

1999 - Iron-rich saponite: dissolution reactions and Cr uptake [Articolo su rivista]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, Luciano; G., Venturelli
abstract

To gain a deeper understanding of the geochemical processes involved in the interactions between ionic solutions and clay minerals in natural systems, the dissolution rate of an Fe-rich saponite from Mt. Prinzera (Taro Valley, Italy) was measured as a function of pH and time at 25 degrees C. Also, its ability to adsorb Cr was studied at varying metal concentrations (3.22, 5.50, 8.50 mEq l(-1)) and with different competing anions (CH3COO-, Cl-, NO3-). It was found that there is a correlation between the experimentally determined release rate constant (k), as defined by the relase of Si, and pH. In acidic solutions, the k values correlate negatively with pH, whereas the opposite occurs for basic solutions. The extent of Cr uptake was measured by analysis of the liquid portion separated by centrifugation after a controlled period of exposure. The Cr adsorbed for different concentrations and anionic environments shows the dependence of Cr uptake on the initial metal concentration and on accompanying anions in the order CH3COO- < Cl- < NO3-.

1999 - Layer modification in exchanged vermiculite saturated with organic compounds: a combined XRD, thermal, FTIR and AFM study [Abstract in Rivista]
Benincasa, Emanuele; Brigatti, Maria Franca; Lugli, Cristina; L., Medici; Poppi, Luciano
abstract

1999 - Ludwigite from central Sweden: new data and crystal structure refinement [Articolo su rivista]
P. W. U., Appel; Brigatti, Maria Franca
abstract

Ludwigite from B-bearing iron ores in the Bergslagen area of central Sweden and in the coastal area north of Stockholm has been studied using chemical and single-crystal diffraction techniques. Structure refinements, completed far three crystals showing slightly different Al contents, in the space group Pbam (agreement factor: 2.42 less than or equal to R less than or equal to 2.79) indicate that: (1) octahedral M1, M2 and M3 bond distances are similar, although the calculated site population suggests that M1 and M2 are nearly completely occupied by Mg whereas M3 also contains Fe2+ and Fe3+; (2) in the M4 octahedron Fe3+ and Al dominate over Mg (and Fe2+); and (3) the distortion parameter, BLD, indicates that M3 is the most regular, whereas M4 is the most distorted octahedron.

1999 - Treatment of industrial wastewater using zeolitite and sepiolite, natural microporous materials [Articolo su rivista]
Brigatti, Maria Franca; Franchini, Giancarlo; P., Frigieri; C., Gardinali; L., Medici; Poppi, Luciano
abstract

This work investigates the ability of natural microporous materials, such as a zeolite-rich tuff(zeolitite) and a modulated phyllosilicate (sepiolite), to remove heavy-metal ions from simulated inorganic polluted industrial wastewater. Fixed beds of sepiolite and zeolitite were percolated by a solution of Co2+, Cu2+, Zn2+, Cd2+, and Pb2+ (concentration of each cation, 2 x 10(-3) N; total concentration, 10(-2) N) and were regenerated with a 2 x 10(-3) N Na+ solution. The order of decreasing affinity was, for sepiolite: Cu2+ > Zn2+ > Cd2+ > Pb2+ congruent to Co2+, and, for zeolitite: Pb2+ much greater than Cd2+ > Cu2+ > Zn2+ > Co2+. After regeneration with Na+ solution, a fraction of the retained heavy metals was quickly released by the beds as follows: sepiolite, Co2+ congruent to Pb2+ > Cd2+ > Zn2+ > Cu2+; zeolitite, Cd2+ > Cu2+ congruent to Zn2+ > Co2+, Pb2+, XRD and DTA-TGA analyses examined structural changes in the natural and final materials.

1998 - Aminoacid as a factor controlling distribution of heavy metals in soils and groundwater [Articolo su rivista]
Brigatti, Maria Franca; Franchini, Giancarlo; Lugli, Cristina; Pinetti, Adriano; G., Vaccari
abstract

The aim of this work is to evaluate the stability of the smectite-aminoacid-Cu2+ system in order to predict the capacity of these minerals to adsorb and to retain pollutants as heavy metals and organics. Two smectites with different crystal chemistry were previously treated with Cu2+ solution in order to obtain Cu2+-exchanged smectite. Afterwards, each natural and Cu2+-treated smectite was suspended and stirred overnight, in 100 ml of 0.2M cysteine or glycine aqueous solutions. The results indicate that: i) glycine and cysteine can be sorbed by natural anti Cu2+-exchanged smectites; ii) the aminoacid content depends on clay mineral chemistry and from the aminoacid type; iii) when treated with acidified distilled water (pH = 5), natural and Cu2+-smectites release glycine almost completely while strongly retain cysteine; iv) the thermal and the X-ray diffraction analyses confirm that cysteine is strongly retained by Cu2+-exchanged samples.

1998 - Aminoacid sorption by Na-, Ca-, and Cu-saturated smectites [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Frigieri, P.; Lugli, Cristina; Poppi, M.
abstract

1998 - Behaviour of sepiolite in Co2+ Cu2+ and Cd2+ removal from a simulated pollutant solution [Articolo su rivista]
Brigatti, Maria Franca; G. C., Franchini; L., Medici; Poppi, Luciano; A., Stewart
abstract

The present study reports on the ability of sepiolite, a hydrous magnesium silicate mineral, to remove metal ions from simulated industrial wastewaters. Fixed beds (weight = 50 g, grain size = 0.30-0.60 mm) of sepiolite from Vallecas (Spain) were percolated by gravity with Co2+, Cu2+ and Cd2+ metal solutions at constant ionic strength. Sepiolite was used both in its natural state and after repeated treatments with Mg2+ solutions at increasing concentrations (10(-2)N, 5x10(-2)N, 10(-1)N). The cation breakthrough and elution curves show that: i) sepiolite beds retain the heavy metals in question in the following order Cd2+ approximate to Co2+ < Cu2+; ii) Ca2+ and Mg2+ are the cations most readily released by untreated beds; iii) after regeneration, the ability of the beds to retain heavy metals is only slightly reduced. X-ray powder diffraction patterns, obtained over a wide temperature range (25 degrees-400 degrees C), and differential thermal analyses results obtained on samples treated with heavy metals are only slightly different from those obtained on natural sepiolite, which suggests that the heavy metals do not significantly affect the layer features.

1998 - Coexisting biotites and muscovites: crystal chemical relationships [Abstract in Rivista]
Brigatti, Maria Franca; P., Frigieri; C., Ghezzo; Poppi, Luciano
abstract

1998 - Complessi tra i minerali dei suoli e composti organici come barriere per la migrazione degli inquinanti negli aquiferi [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, Luciano
abstract

1998 - Crystal chemistry of zinnwaldites [Abstract in Rivista]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, Luciano; E. E., Foord; D., Kile
abstract

1998 - Crystal chemistry of Li-bearing micas from the Pikes Peak batholith, Central Colorado [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, M.; Foord, E. E.; Kile, D.
abstract

1998 - Crystal chemistry of Mg-, Fe-bearing muscovites-2M(1) [Articolo su rivista]
Brigatti, Maria Franca; P., Frigieri; Poppi, Luciano
abstract

Phengitic muscovite-2M(1), crystals [([12])(K0.88-0.99Na0.01-0.09Ca0.Ba-00-0.06(0.00-0.01))([6])(Al1.64-1.88Fe0.06-0.292+Fe0.01-0.163+Mg0.00-0.16Mn0.00-0.07Ti0.00-0.06)([4])(Si2.87-3.30Al0.70-1.13)(OH)(1.56-2.07)F0.00-0.41O9.91-10.25] from peg matites and peraluminous granites were refined to investigate the influence of phengitic substitution on the mica structure. Single-crystal X-ray diffraction data were collected for eleven crystals in the C2/c space-group (agreement factor 2.1% less than or equal to R-obs less than or equal to 3.9%). Tetrahedral Si and Al cation disorder was found for each sample, with the mean tetrahedral cation-oxygen distances ranging from 1.639 Angstrom less than or equal to <T1-O> less than or equal to 1.647 Angstrom and 1.640 Angstrom less than or equal to <T2-O> less than or equal to 1.646 Angstrom. As phengitic substitution increases, the octahedral sheet expands and requires a less distorted (more hexagonal) tetrahedral ring (7.70 degrees less than or equal to alpha less than or equal to 11.38 degrees) and low corrugation of the basal O plane (0.1796 Angstrom less than or equal to Delta z less than or equal to 0.2296 Angstrom). The electron density at the M2 site is greater than that required for the ideal muscovite-2M(1), structure, and a small excess of electron density is found in the M1 site. The inner sixfold coordination of the interlayer (A) cation is elongated along c*, which is consistent with the high or values and the long A-O11 bond length.

1998 - Crystal chemistry of biotites from mafic enclaves in the Warburton granodiorite, Lachlan Fold Belt (Australia) [Articolo su rivista]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, Luciano; M., Elburg
abstract

This study details the crystal chemical features of biotite crystals from host granodiorite and mafic microgranitoid enclaves in the Warburton Granodiorite (Lachlan Fold Belt, Australia), a small (similar to 80 km(2)) S-type pluton within the Melbourne basement terrain of the Lachlan Fold Belt. Biotites are the most abundant mafic minerals in both enclaves and host rock, with Fe/(Fe+Mg) ratio ranging from 0.47 to 0.54. Differences in chemical composition concern their Ba and Ti content, which are higher in host granodiorite. The Al for Si substitution, greater than the ideal value, suggests the presence of exchange vectors involving octahedral, tetrahedral and interlayer substitutions. Actually, the exchange vectors (K-1+[4]Si-14+[12]Ba2+[4]Al3+)-K-[12], (Mg-12+[4]Si-24+[6]Ti4+[4]Al23+)-Mg-[6],(Al-13+[4]Si-14+[6]Ti4+[4]Al3+)-Al-[6] are observed. Nevertheless, other vectors involving anionic sites may be present. The crystal structure refinements (2.8 less than or equal to R-obs (%) less than or equal to 3.9), carried out in the space group C2/m, indicate that the crystals are mostly 1M polytype. The disordered pattern of octahedral cation distribution may indicate a relatively quickly cooling of Warburton Granodiorite and of enclaves it contains.

1998 - Crystal structure refinement of ludwigite from central Sweden [Abstract in Rivista]
P. W. U., Appel; Brigatti, Maria Franca
abstract

1998 - Iron-rich saponite: Cr uptake and dissolution reactions. [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, M.; Venturelli, G.
abstract

1998 - Role of exchange cations and layer charge localization of smectites in the sorption and retention of cysteine [Abstract in Rivista]
Brigatti, Maria Franca; Lugli, Cristina; S., Montorsi; Poppi, Luciano
abstract

1997 - Ba-rich celestine: New data and crystal structure refinement [Articolo su rivista]
Brigatti, Maria Franca; Galli, Ermanno; Medici, L.
abstract

A Ba-rich celestine (Sr0.87Ba0.13SO4) filling cavities of volcanoclastic rocks from Montecchio Maggiore (Vicenza, Italy) was studied. The role of the Ba content in the mineral was determined using X-ray powder data, single crystal X-ray refinement, thermal and chemical analyses. The unit cell parameters (obtained by single crystal diffraction) are a = 8.408, b = 5.372, c = 6.897 Angstrom, and the refinement in the space group Pnma (Z = 4) gives the final R value of 0.039. The average (Sr,Ba)-oxygen bond length is 2.842 Angstrom and agrees with an occupancy of Sr 87% and Ba 13%. Individual bond lengths (Sr,Ba)-O and bond strength calculations confirm that all twelve interactions are significant and define an irregular array around the cation.

1997 - Clintonite-1M: Crystal chemistry and its relationships to closely associated Al-rich phlogopite [Articolo su rivista]
Alietti, E.; Brigatti, Maria Franca; Poppi, Luciano
abstract

Crystal-structure refinements were performed on clintonite-1M crystals [ideal composition Ca-[6]([6])(Mg2Al)([4])(SiA1(3))O-10(OH)(2)] from skarns of the Predazzo-Monzoni area and Adamello Massif (northern Italy) with the aim of characterizing some aspects of their crystal chemistry and their relationships with closely associated phlogopite-1M. In the clintonite samples examined, the tetrahedral composition ranges from Si1.19Al2.78Fe0.03 to Si1.28Al2.70Fe0.02, indicating that the extent of the exchange vector (Al-1Mg-2Si[6])-Al-[4]-Mg-[6]-Si-[4](Al,square), which links trioctahedral with dioctahedral Ca-bearing brittle micas, was very limited. Single-crystal X-ray diffraction data were collected and structure refinements completed in space group C2/m converging to R-obs from 0.027 to 0.037 for six samples. The Al-[4](3+) for Si-[4](4+) substitution, which is close to 70%, produces more regular and flatter tetrahedra than in the case of phlogopite, together with an increase in the thickness and in the lateral dimensions of the sheet; the presence of Al3+ in octahedral coordination, on the other hand, reduces the dimensions of both M1 and M2 sites with a consequent decrease in the thickness of the sheet. The volume, the flattening angle Psi, and the central cation off-center shift (BLD) of the trans M1 octahedral site are greater than those of the cis M2 site, thus indicating a normal octahedral ordering. The high misfit value (from 1.187 to 1.326 Angstrom) between tetrahedral and octahedral sheets is mostly compensated by the distortion of the tetrahedral ring (tetrahedral rotation angle alpha: 23.1 less than or equal to alpha less than or equal to 24.9 degrees). Relative to phlogopite,the interlayer separation in clintonite is reduced by about 0.6 Angstrom.

1997 - Complessi metalli pesanti-amminoacidi-minerali delle argille nei terreni sottostanti le discariche RSU [Relazione in Atti di Convegno]
Brigatti, Maria Franca; G. C., Franchini; A., Pinetti; Lugli, Cristina; G., Vaccari
abstract

1997 - Crystal chemistry and microstructures of Al-rich warwickite [Abstract in Rivista]
P. W. U., Appel; Bigi, Simona; Brigatti, Maria Franca
abstract

1997 - Crystal chemistry of biotite from mafic enclaves, Warburton Granodiorite, Lachlan Fold Belt (Australia) [Abstract in Rivista]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, Luciano
abstract

1997 - Crystal chemistry of muscovites: single crystal X-ray study [Abstract in Rivista]
Brigatti, Maria Franca; P., Frigieri
abstract

1997 - Crystal structure of biotites-1M from microgranitoid enclaves [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, Luciano
abstract

1997 - Crystal structure refinement of aluminian lizardite-2H(2) [Articolo su rivista]
Brigatti, Maria Franca; Galli, Ermanno; Medici, L; Poppi, Luciano
abstract

Well-crystallized euhedral crystals of aluminian lizardite-2H(2) (Mg2.35Fe0.062+Fe0.073+Al0.52) (Si1.41Al0.59)O-5.00(OH)(4.00) were found near Schio (Vicenza, Italy). To gain insight into the role of a high Al content lizardite, chemical analyses and single-crystal X-ray data collection were conducted. Structure refinement, completed in space group P6(3) (agreement factor R = 0.034), gives mean T-O values of 1.654 Angstrom and 1.664 Angstrom for T1 and T2 sites, respectively. The ditrigonal distortion of the six-membered tetrahedral ring is positive (alpha = +9.7 degrees), as expected for the 2H(2) polytype. The octahedral site has a mean bond length similar to that of the Mg-rich octahedra of amesite and distortion parameters similar to those of Al-rich octahedra.

1997 - Effect of heavy metals in aminoacid adsorption by smectite [Relazione in Atti di Convegno]
B., Boccaccino; Brigatti, Maria Franca; G. C., Franchini; G., Vaccari
abstract

1997 - Effect of pH and heavy metal cations on ophiolitic rock alteration product [Abstract in Rivista]
Brigatti, Maria Franca; P., Frigieri; Lugli, Cristina; Poppi, Luciano; G., Venturelli
abstract

1997 - Factors affecting the transport and recovery of heavy metals and organic pollutants in smectitic soils [Abstract in Rivista]
Brigatti, Maria Franca; P., Frigieri; Lugli, Cristina; Poppi, Luciano
abstract

1997 - Kinetics of sorption reactions on sepiolite, a modulated layer silicate [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, Cristina; Poppi, Luciano
abstract

1997 - Porous natural network in heavy metal enviromental control [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, Cristina
abstract

1997 - Removal of heavy metal ions by sepiolite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Lugli, C.; Medici, L.; Poppi, Luciano
abstract

1997 - V3+, Cr3+ and Mn2+ uptake by sepiolite and sedimentary zeolites. [Articolo su rivista]
Brigatti, Maria Franca; Medici, L.; Poppi, Luciano
abstract

The aim of this study was to investigate the potential usefulness of minerals in industrial waste-water treatment. Fixed beds, one of a zeolite-rich rock (zeolitite) and the other of a phyllosilicate (sepiolite), were treated with a soln. of heavy-metal cations (V3+, Cr3+, Mn2+) in equal concns. of 3.33×10-3 N. To ascertain the different rates heavy metal uptake and subsequent release, the beds were eluted with a Na+ soln. (3.33 × 10-3 N) and the cations (V3+, Cr3+, Mn2+, Na+, Mg2+, K+, Ca2+) in soln. measured. At first, the heavy-metal cation level in the effluent was consistently low for both beds; thereafter, it was obsd. that: (i) the ability of sepiolite to retain V3+ and Cr3+ is greater than that of zeolitite, whereas zeolitite reveals greater affinity for Mn2+; (ii) the max. heavy metal release occurs in the initial stage and slows down as the amt. of influent soln. increases; (iii) the residue of heavy metals in the beds after elution does not significantly affect the mineral structure.

1996 - Comparison between zeolite and sepiolite in the treatment of heavy metal polluted waters [Relazione in Atti di Convegno]
Brigatti, Maria Franca; P., Frigieri; Galli, Ermanno; C., Gardinali; L., Medici
abstract

1996 - Crystal chemistry and petrologic significance of Fe3+-rich phlogopite from the Tapira carbonatite complex, Brazil [Articolo su rivista]
Brigatti, Maria Franca; Medici, L; Saccani, E; Vaccaro, C.
abstract

This contribution deals with the crystal chemistry of phlogopite and Fe3+-rich phlogopite from the Tapira alkaline-carbonatite complex (Brazil) to assess the petrological significance and genetic conditions of these rocks. The Tapira complex consists of a layered intrusion composed mainly of ultramafic rocks (dunite, wehrlite, clinopyroxenite, bebedourite, garnet-magnetitite, perovskite-magnetitite, and glimmerite) with subordinate carbonatite. The wide range of textural, optical, and crystal-chemical characteristics of phlogopite is related to the variation of f(O2), a(H2O), and a(CO2) as well as magma bulk-chemical composition during fractional crystallization. Phlogopite from alkaline-silicate rocks (ranging from dunite to bebedourite) is characterized by fairly constant Al content, moderate Fe-[4](3+) substitution, and variable amounts of Ti. The Fe-[4](3+) substitution, accompanied by crystals showing reverse pleochroism, increases during fractional crystallization. These features correspond to crystallization at low pressure and high f(O2) and a(H2O) in the presence of moderate saturation in Ti-bearing phases, Al2O3 in the magma, or both. Phlogopite from silicate-carbonatite rocks, classified as ferriphlogopite on the basis of strong reverse pleochroism related to Fe-[4](3+) tetrahedral substitution, also presents low to very low Al, Fe2+, and Ti contents. These features suggest very high f(O2), H2O, and CO2 conditions in the presence of strong saturation in Ti-bearing phases as well as very low Al2O3 content in the liquid. The crystal-structure refinements of Tapira phlogopite show that Fe3+ substitutes for Si in tetrahedral sites; Fe distribution is completely disordered, so the resulting space group is C2/m. The octahedral-site composition is similar to that of phlogopite, the octahedral sites being preferentially occupied by Mg. The presence of Fe3+ in the tetrahedral sheet enlarges the whole structure. This enlargement is reflected by an increase in cell-edge lengths and a decrease in beta-angle values. The increase in distortion of the tetrahedral ring (alpha angle up to similar to 11 degrees) is necessary for the tetrahedral and octahedral sheets to fit together.

1996 - Crystal structure refinement of aluminian-lizardite-2H2 [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Galli, Ermanno; L., Medici; Poppi, Luciano
abstract

1996 - I canali strutturali della sepiolite e la interazione con soluzioni di Cd2+, Co2+ e Cu2+. [Relazione in Atti di Convegno]
Brigatti, Maria Franca; G. C., Franchini; L., Medici; Poppi, Luciano; A., Stewart
abstract

1996 - Interazioni tra soluzioni acquose a diverso pH e materiali smectitici derivanti dall’alterazione di serpentiniti. [Relazione in Atti di Convegno]
Brigatti, Maria Franca; L., Medici; M., Panzarino; Poppi, Luciano; G. P., Venturelli
abstract

1996 - La localizzazione della carica di strato in smectiti e i processi di adsorbimento e scambio di metalli pesanti. [Relazione in Atti di Convegno]
Brigatti, Maria Franca; G., Campana; L., Medici; Poppi, Luciano
abstract

1996 - Mineralogia e recupero ambientale: le argille [Capitolo/Saggio]
Brigatti, Maria Franca; Medici, L.
abstract

1996 - Mixed-layer chlorite/smectite (corrensite) in ophiolitic rock alteration products [Articolo su rivista]
Brigatti, Maria Franca; Valdré, G.
abstract

Corrensite from the Tare Valley (Northern Apennine, Italy) was examined with X-ray powder diffraction (XRD) and high resolution transmission electron microscopy (TEM). XRD showed that the mineral is a well ordered corrensite, i.e. with regular 1:1 chlorite/smectite stacking. The TEM study (selected area diffraction patterns and lattice-fringe images) showed that the predominant types of stacking belong to collapsed di- or trioctahedral smectite-like minerals and to chlorite. The arrangement of alternating chlorite and collapsed smectite layers (14+10 Angstrom), which is typical of corrensite, is uncommon.

1996 - Refinement of the structure of natural ferriphlogopite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; P., Frigieri; L., Medici; Poppi, Luciano
abstract

1996 - Refinement of the structure of natural ferriphlogopite [Articolo su rivista]
Brigatti, Maria Franca; Medici, L; Poppi, Luciano
abstract

Two ferriphlogopite-1M crystals with a composition (K0.99Na0.01)(Sigma=1.00)(Mg2.73Fe0.172+Fe0.083+-Ti-0.01)(Sigma=2.99)[(Fe0.953+Si3.05)(Sigma=4.00)O-10.17] (OH)(1.79)F-0.04 (sample S1) and (K-1.02)(Sigma=1.02)(Mg2.68Fe0.202+Fe0.113+Mn0.01)(Sigma=3.00)(Fe0.953+Si3.05)(Sigma=4.00)O-10.18](OH)(1.75)F-0.07 (sample S2) occur within an alkali-carbonatic complex near Tapira, Belo Horizonte, Minas Gerais, Brazil. Each crystal was studied by single-crystal X-ray diffraction. The least-squares refinements of space group C2/m resulted in R values of 0.031 for S1 and 0.025 for S2. Results showed that Fe3+ substitutes for Si within the tetrahedral sites and that the Fe distribution is fully disordered. The octahedral sites are preferentially occupied by Mg. The presence of Fe3+ within the tetrahedral sheet produces increased cell edge lengths. For sample S1, a = 5.362 Angstrom, b = 9.288 Angstrom, c = 10.321 Angstrom and the monoclinic beta angle was: beta = 99.99 degrees. For sample S2, a = 5.3649 Angstrom, b = = 9.2924 Angstrom, c = 10.3255 Angstrom and the monoclinic beta angle was: beta = 99.988 degrees. The tetrahedral rotation angle of alpha = 11.5 degrees is necessary for tetrahedral and octahedral sheet congruency. The enlarged tetrahedral sites are regular, with cations close to their geometric center. Ferriphlogopites have identical mean bond lengths for M1 and M2 sites within standard deviation. The M1-O3 and M2-O3 bond lengths are longer than the mean so that O3 may articulate with the tetrahedra.

1996 - Selective removal of heavy-metal ions by zeolitite and sepiolite [Abstract in Rivista]
Brigatti, Maria Franca; P., Frigieri; F., Gibellini; C., Gardinali; L., Medici; Poppi, Luciano
abstract

1996 - Sepiolite and industrial waste-water purification: Removal of Zn2+ and Pb2+ from aqueous solutions [Articolo su rivista]
Brigatti, Maria Franca; Medici, L; Poppi, Luciano
abstract

The interaction between sepiolite and Zn2+ and Pb2+ aqueous solutions has been studied in order to verify the heavy-metal cation sorption-desorption rates. To this end, weighed amounts of sepiolite were placed in two conventional chromatographic columns and percolated at constant temperature, flow rate, pH and percolating solution concentration (0.5 x 10(-2) M, with Zn2+ or Pb2+, Mg2+ and 10(-2) M Na+, respectively). The amount of cations retained and released by the sepiolite bed in the effluent solution was analyzed by atomic absorption and UV-Visible spectrophotometries. The experimental results indicate that: (i) heavy-metal cation sorption can occur on the surface of broken edges, in channels and at specific sites according to crystal chemical affinity: Mg2+ sites are mostly affected by Zn2+-treatment and Ca2+ sites by Pb2+- treatment (Zn2+-treated bed, Mg2+/Ca2+ = 0.627; Pb2+-treated bed, Mg2+/Ca2+ = 0.475); (ii) repeated treatments with heavy-metal cation solutions produce a decrease in adsorption and/or exchange capacity of the sepiolite bed; however, even when sepiolite is treated with alkali and earth alkali cations, it is able to retain a heavy-metal cation fraction, the retention of Zn2+ being greater than that of Pb2+. In order to investigate the chemical variation induced in sepiolite crystals by interaction between Zn2+ and Pb2+ solutions, a natural sample was treated with 1 M Zn2+ and 1 M Pb2+ solutions and then analyzed by X-ray powder diffraction and by differential thermal and thermogravimetric techniques.

1996 - Soluzioni acquose contenenti Zn2+ e Pb2+: possibilità di purificazione con letti di sepiolite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; L., Medici; Poppi, Luciano; S., Roli
abstract

1996 - The influence of layer charge on Zn2+ and Pb2+ sorption by smectites [Articolo su rivista]
Brigatti, Maria Franca; Campana, G; Medici, L; Poppi, Luciano
abstract

Two smectites with different layer charge localization were used to characterize the chemical and structural aspects of minerals treated with 1.9 x 10(-2) M and 1 M heavy metal solutions (Zn2+ and Pb2+). Natural and treated smectites were analysed by: (1) X-ray powder diffraction first at 25 degrees C and relative humidity of 60% and then at increasing temperature up to 400 degrees C; (2) thermogravimetric and differential thermal analysis; (3) X-ray fluorescence; (4) atomic absorption and UV visible spectrophotometries. The sorption of both metals depends on 2:1 layer features and is enhanced when the total layer charge is mostly due to substitution in the octahedral sheet. The variability between Zn2+- and Pb2+-treated smectites in the interlayer water content depends both upon cation electrostatic features and upon smectite layer charge localization. The greatest water content was observed in [Zn2+]1 M-treated smectite showing charge imbalance in the octahedral sheet. In smectites treated with [Zn2+]1M solutions, an additional thermal reaction occurs at a temperature of similar to 380 degrees C, and the d(001) spacing, which is 10 Angstrom at a temperature of similar to 200 degrees C, gradually decreases in the temperature range 200-400 degrees C. In smectites treated with 1 M [Pb2+] solutions this value is reached at a temperature of similar to 150 degrees C and remains quite constant up to 400 degrees C.

1996 - Use of sepiolite in zinc polluted industrial waste water purification. [Articolo su rivista]
Brigatti, Maria Franca; Frigieri, P.; Medici, L.; Poppi, Luciano; Roli, S.
abstract

The possibility of controlling Zn in industrial wastewater was studied using modulated phyllosilicate, sepiolite. Its effectiveness was assessed after regeneration when changes in the mineral crystal chem. may have occurred as a result of treatment. In order to simulate what happens when measures are taken to reduce water pollution, the interaction between sepiolite and Zn2+ in aq. solns. was studied through the measurement of the Zn2+ sorption-desorption rates. Zn2+ retention by the sepiolite bed becomes limited, but not abolished, by repeated regeneration with Na+ solns. at increasing concns. The Zn2+-treated sepiolite structural features are only slightly influenced by Zn2+ partly exchanged for Mg2+.

1996 - Zn2+ and Pb2+ polluted waste waters: interaction with soil smectites [Relazione in Atti di Convegno]
Brigatti, Maria Franca; G. C., Franchini; L., Medici; Poppi, Luciano; G., Vaccari
abstract

1995 - Adsorbimento di Zn2+ e Pb2+ da parte della caolinite. [Articolo su rivista]
Alietti, E.; Brigatti, Maria Franca; Campana, G.; Medici, L.; Poppi, Luciano
abstract

1995 - Ba-rich celestite: new data and crystal structure refinement [Abstract in Rivista]
Brigatti, Maria Franca; Galli, Ermanno; L., Medici
abstract

A Ba-rich celestine (SrOX7BaO13S04) filling cavities of volcanoclastic rocks from Montecchio Maggiore(Vicenza, lIaly) was studied. The role of the Ba content in the mineral was determined using X-ray powderdata, single crystal X-ray refinement, thermal and chemical a!1alyses. The unit cell parameters (obtained bysingle crystal diffraction) are a =8.408, b =5.372, c =6.897 A, and the refinement in the space group Pnma(Z =4) gives the final R value of 0.039. The average (Sr,Ba)-oxygen bond length is 2.842 A and agrees withan occupancy of Sr 87% and Ba 13%. Individual bond lengths (Sr,Ba)-O and bond strength calculationsconfirm that all twelve interactions are significant and define an irregular array around the cation.

1995 - Comportamento di montmorilloniti a diversa carica di strato allo scambio di Zn2+ e Pb2+ presenti in soluzioni acquose. [Articolo su rivista]
Brigatti, Maria Franca; Campana, G.; Medici, L.; Poppi, Luciano
abstract

1995 - Cristallochimica di miche fragili: le clintoniti [Abstract in Rivista]
E., Alietti; Brigatti, Maria Franca
abstract

1995 - Interaction between montmorillonite and pollutants from industrial waste-waters: exchange of Zn2+ and Pb2+ from aqueous solutions. [Articolo su rivista]
Brigatti, Maria Franca; Corradini, F.; Franchini, Giancarlo; Mazzoni, S.; Medici, L.; Poppi, Luciano
abstract

he interactions between montmorillonite (sample SAz-1 from the Source Clay Repository of the Clay Minerals Society) and Zn2+ and Pb2+ solutions of different ionic strengths (from about 10−5 to 1 M) are studied in order to observe changes in the clay-solution system and mineral crystal chemistry. In both types of solution the stationary state of exchange, attained within 20 min, depends on the solution's ionic strength. The uptake can be interpreted by means of a Langmuir-type equation with Zn2+ somewhat more easily exchanged than Pb2+. The shifting of the d(001) spacing from 15.3 Å (natural sample) to 12.8 Å (Zn2+-exchanged montmorillonite) and 12.4 Å (Pb2+-exchanged montmorillonite) suggests that the kind of interlayer cation affects the c dimension of the layer. Upon heating, the exchanged montmorillonite layer collapses (d(001),Zn = 9.5 Å; d(001),Pb = 10.0 Å) and the closest packing is attained at T = 200°C for Pb2+ - and at 380°C for Zn2+-exchanged samples. In addition to reactions observed for natural and Pb2+-exchanged samples in the temperature ranges 20–250°C and 500–700°C, the thermal analyses of Zn2+-exchanged montmorillonite show a reaction at about 380°C which can be related either to strongly bonded water molecules or to “brucitic-like” interlayers or to Zn2+-exchanged octahedra.

1995 - Interaction of Zn2+ and Pb2+ aqueous solutions with sepiolite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Medici, L.; Poppi, Luciano
abstract

1995 - La sepiolite e la purificazione di reflui industriali: processi di adsorbimento e cessione di Zn2+ e Pb2+ in soluzione acquosa [Abstract in Rivista]
Brigatti, Maria Franca; P., Giovannini; L., Medici; Poppi, Luciano; G., Vaccari
abstract

1995 - Montmorillonite layer-charge and its importance in transport mechanism of polluted solutions [Abstract in Rivista]
Brigatti, Maria Franca; L., Medici; Poppi, Luciano
abstract

1995 - Phlogopites from the alkaline-carbonatite complex of Tapira (Brazil): implications for their petrogenetical significance [Abstract in Rivista]
Brigatti, Maria Franca; L., Medici; E., Saccani; C., Vaccaro
abstract

1995 - Purificazione di reflui industriali con la sepiolite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; G. C., Franchini; L., Medici; Poppi, Luciano; G., Vaccari
abstract

1995 - THE CRYSTAL-STRUCTURE AND CHEMISTRY OF HIGH-ALUMINUM PHLOGOPITE [Articolo su rivista]
Alietti, E; Brigatti, Maria Franca; Poppi, Luciano
abstract

Crystal structure refinements were performed on five Al-rich phlogopite-1M crystals (1.50 less than or equal to Al3+ less than or equal to 1.97 atoms per formula unit) from skarns of the Predazzo and Monzoni Hills petrographic area (north-east Italy) with the aim of characterizing geometrical variation produced by Al3+ increase. The charge imbalance was mostly compensated for by substitutions of highly charged cations in the octahedral sheet (Al3+ and/or Fe3+ for Mg2+). The refinements were carried out in the mean space group C2/m and gave agreement values (R) between 0.025 and 0.030. For some additional crystals, only chemistry and/or unit cell parameters were determined. In all samples the tetrahedra are more regular and larger than those previously reported in the literature for phlogopite crystals and the misfit between tetrahedral and octahedral sheets, produced by the increase in the tetrahedral edges, is mostly compensated for by the tetrahedral ring angle rotation alpha (10.2 degrees less than or equal to alpha less than or equal to 12.5 degrees), whereas the octahedral sheet features seem affected only by local crystal-chemical variations.

1995 - Transmission electron microscopy study of mixed-layer chlorite/smectite (corrensite) in ophiolite rock alteration products [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Valdré, G.
abstract

1994 - CRYSTAL-CHEMISTRY AND MICROSTRUCTURES OF PLUTONIC BIOTITE [Articolo su rivista]
Bigi, Simona; Brigatti, Maria Franca
abstract

Transmission electron microscope and single-crystal X-ray diffraction studies were carried out on biotite from the Valle del Cervo plutonic body (northwestern Italy) with the aim of characterizing their structures and microstructures and also of establishing possible relationships between polytypism and crystal chemistry. The crystals, from the same lithologic complex, do not present significant chemical variations. On the other hand, they contain many different polytypic sequences, such as 1M and 2M1, which represent the most common polytypes, 3T and disordered and long-period stacking sequences, which often coexist in the same crystal. Four-, five-, six-, seven-, eight-, nine-, 13-, 14-, and 21-layer polytypes, often interrupted by stacking faults, were also observed. No relationship was found between polytypic sequences and chemistry, whereas the observed microstructures seem to be related to the petrological environment. The microstructural study facilitated the interpretation of difference-Fourier maps obtained from structure refinements of biotite from the same rock samples. The crystal-chemical study of two biotite samples, 1M (space group C2/m) and 2M1 (space group C2/c), from the same rock sample and with very similar chemical composition did not reveal any substantial differences in the mean bond lengths, whereas the octahedral and tetrahedral distortion parameters are higher in 2M1 than in 1M. Both polytypes exhibit M1 mean bond lengths greater than M2 mean bond lengths, suggesting partial cation ordering, whereas no tetrahedral cation ordering can be detected in the 2M1 polytype.

1994 - Crystal chemistry and variations in layer geometry [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1994 - Distorsioni medie reali nel foglio tetraedrico delle miche [Relazione in Atti di Convegno]
E., Alietti; Brigatti, Maria Franca; G., Valdré
abstract

1994 - Interaction between montmorillonite and pollutants from the industrial wastewaters: exchange of Zn2+ and Pb2+ from aqueous solutions [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Corradini, F.; Franchini, G. C.; Mazzoni, S.; Medici, L.; Poppi, Luciano
abstract

1994 - Interaction of exchanged Zn2+-montmorillonite with alkaline and earth alkaline cations [Articolo su rivista]
Brigatti, Maria Franca; Corradini, F.; Franchini, G.; Pacchioni, M. G.; Poppi, Luciano
abstract

Desorption of Zn2+ by montmorillonite in alkaline and earthalkaline environments was carried out at room temperature and at pH 6.0 using the following techniques: a combination of analytical methods to determine the variation of montmorillonite chemical composition, X-ray powder diffraction (at controlled relative humidity and at controlled temperature in the range 50°C≤T≤400°C) and thermal analysis. The desorption isotherms clearly show that some of the Zn2+cations are retained in the layers, the proportion being greater when the montmorillonite is treated with Na+ and smaller when treated with Mg2+. The d(001) basal spacing, for samples teated with Na+-K+ and Na+-Ca2+ mixed solutions, appears to be mainly affected by the first appearance of K+ and Ca2+. Differential thermal analyses of Zn2+-exchanged samples shows two dehydroxylation reactions at about 380 and 650°C which emphasized that Zn2+ is differently bonded in the layers and hence differently released.

1994 - THE ROEDDERITE-CHAYESITE SERIES FROM SPANISH LAMPROITES - CRYSTAL-CHEMICAL CHARACTERIZATION [Articolo su rivista]
Alietti, E; Brigatti, Maria Franca; Capedri, Silvio; Poppi, Luciano
abstract

Members of the roedderite-chayesite series in lamproites from Cancarix (SE Spain), crystallized from late magmatic residua under low P-H2O, high temperature (similar to 1100 degrees C), oxidizing conditions. They exhibit the following main chemical variations: 0.14 less than or equal to Na less than or equal to 0.62 atoms per formula unit (apfu); 0.80 less than or equal to K less than or equal to 1.00 apfu; 2.97 less than or equal to Mg less than or equal to 4.33 apfu; 0.00 less than or equal to Fe2+ less than or equal to 1.19 apfu; 0.42 less than or equal to Fe3+ less than or equal to 0.87 apfu; they are hexagonal (10.120 less than or equal to a less than or equal to 10.135 Angstrom, 14.305 less than or equal to c less than or equal to 14.326 Angstrom), P6/mcc. The characteristic chemical substitution is: Fe3+ + square reversible arrow Fe2+ + (K+Na)(+). Six crystal structures have been refined to 0.020 g R(obs) less than or equal to 0.026. They have the osumilite/milarite-type structure, with Si entering the double tetrahedral T1 six-membered rings, and Mg and Fe entering both the ring-linking T2 tetrahedra, and the A octahedra. The 12-coordinated C site, located between two double rings of T1 tetrahedra, is occupied mainly by K and subordinately by Na. Furthermore, Na occupies the partially empty nine-fold coordinated B site which occurs both in the ideal (z = 0) and in a split-atom position along the c direction.

1994 - The crystal chemistry of high-aluminium phlogopite [Relazione in Atti di Convegno]
Alietti, E.; Brigatti, Maria Franca; Poppi, Luciano
abstract

1994 - The roedderite-chayesite series: crystallographic relation [Abstract in Rivista]
E., Alietti; Brigatti, Maria Franca; Capedri, Silvio; Poppi, Luciano
abstract

1993 - Cristallochimica e microstrutture di flogopiti e clintoniti geneticamente associate. [Relazione in Atti di Convegno]
E., Alietti; Bigi, Simona; Brigatti, Maria Franca; Poppi, Luciano
abstract

1993 - Crystal chemical variations in Ba-rich biotites from gabbroic rocks of lower crust (Ivrea Zone, NW Italy) [Articolo su rivista]
Bigi, Simona; Brigatti, Maria Franca; Mazzucchelli, Maurizio; Rivalenti, Giorgio
abstract

Biotites from mafic rocks occurring at different stratigraphic levels of the Ivrea-Verbano Mafic Complex are studied. The rocks are gabbros and diorites. All the biotites are intermediate between phlogopite and annite [0.28<Fe/(Mg+Fe)<0.66]. Biotites from gabbros are enriched in BaO and TiO2 (up to 7.14 and 9.32 wt%, respectively) with respect to those of the diorites (up to 1.26 and 6.26 wt%, respectively). Systematic compositional variations support the substitution model 2(IV)Si + ((VI)R2+) half arrow left over half arrow right 2(IV)Al + (VI)Ti (R2+ = Fe + Mg + Mn) in gabbros and (IV)Si + (VI)Al half arrow right over half arrow left (IV)Al + (VI)Ti in diorites. A predominance of disordered stacking sequences, coexisting with 1M, 2M1 and 3T polytypes was observed in all biotites. It was possible to carry out structural refinements only on three biotites-2M1 from diorites (R-values between 2.68 and 3.77) 'and one biotite-1M from gabbros (R-value=3.09). It was shown that: (1) the reduced thickness of the tetrahedral sheet in Ba-rich biotites supports the coupled substitution (IV)Si + (XII)K half arrow left over half arrow right (IV)Al + (XII)Ba; (2) the interlayer site geometry is affected by the whole layer chemistry and does not reflect only local chemical variations; (3) in two samples of the 2M1 polytype, the M(1) octahedral site is larger and more distorted than the M(2) sites because of the preferential ordering of Fe2+ in the M(1) site, whereas one sample shows complete cation disorder in the octahedral sites. Biotite-1M shows that Fe2+ can also be located in the M(2) site. Some of the differences between the biotites of gabbros and diorites (e.g. Ba concentration and exchange vectors) may be linked to the host rock composition and to its crystallization process. Biotite occurs in trace amounts in gabbros and its crystallization is related to the interstitial melt which contributed to the adcumulus growth of the main rock forming phases and became highly enriched in K, Ba and Ti. Diorites are the result of equilibrium crystallization of a residual melt rich in incompatible elements, where biotite is a major constituent.

1993 - Crystal chemistry and cation ordering in pseudobrookite and armalcolite from Spanish lamproites. [Articolo su rivista]
Brigatti, Maria Franca; Contini, S.; Capedri, Silvio; Poppi, Luciano
abstract

Pseudobrookite-like minerals from two outcrops of Spanish lamproites (Jumilla, Murcia province, and Cancarix, Albacete province) cover the compositional range: Fe1.63+Mg0.2Ti1.2O5−Fe0.63+Mg0.7Ti1.7O5−Fe0.23+Fe0.62+Mg0.3Ti1.9O5 thus they range between pseudobrookite and armalcolite. Al, Cr, Mn, Ca, Zr and Nb are minor elements. Single crystal X-ray structural refinements, in the space group Bbmm, give R-values between 0.016 and 0.024. The structural refinements show that: (1) M1 site has wider variations in mean bond lengths and is larger and more distorted than M2 site because of the preferential ordering in the M1 site of Mg and Fe3+ in respect to Ti; (2) the cation ordering is probably controlled both by chemical environment and temperature of crystallization. In particular, ordering in pseudobrookites from rocks of comparable composition increases under decreasing temperature of crystallization; (3) in Jumilla rocks, the highest in oxygen activity among the lamproites analyzed (above the NNO buffer), all the iron in pseudobrookite occurs in the trivalent state, whereas in Cancarix and Las Minas de Helin, close to NNO and QFM buffers respectively, iron is present also in the divalent state

1993 - Crystal chemistry of Ba-rich trioctahedral micas-1M. [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

Ten single-crystal X-ray structure refinements of igneous and metamorphic Ba-bearing micas were determined to define the exchange vectors required to compensate for the excess in positive layer charge caused by [XII]Ba2+ for [XII]K+ substitution. The determined exchange vector is BaAlK−1Si−1. The micas have a Ba2+ content in the range 0.01-1.09 apfu (atoms per formula unit) with octahedra mostly populated by Mg2+ (2.21 ≤ Mg2+ ≤ 3.07 apfu) and Fe2+ (0.13 ≤ Fe2+ ≤ 1.53 apfu). All samples are 1M polytype and the structure were refined in space group C2/m (0.020 ≤ R ≤ 0.034). lncreasing the substitution of [IV]Al3+ for [IV]Si4+ distorts the tetrahedra by progressively increasing the dimensions of the basal edges. This increase in the lateral dimensions of the tetrahedral sheet allows for a greater rotation angle α (5.9 ≤ α ≤ 11.5). Octahedral sheet crystal chemical features (ordering pattern, size and distortion of both M(1) and M(2) sites) are similar to those reported for micas in the phlogopite-annite join. The most notable variation involves the length of M(1) unshared edges, which decreases in samples with the highest [XII]Ba2+ content

1993 - Interaction of exchanged Zn2+-montmorillonite with alkaline and earth alkaline cations [Abstract in Rivista]
Brigatti, Maria Franca; F., Corradini; Franchini, Giancarlo; M. G., Pacchioni; Poppi, Luciano
abstract

1993 - The adsorption of Pb2+ and Zn2+ metal cations by montmorillonite and kaolinite [Abstract in Rivista]
Brigatti, Maria Franca; F., Corradini; Franchini, Giancarlo; L., Medici; Poppi, Luciano
abstract

1993 - The roedderite-chayesite series from Spanish lamproites: chemical and crystallographic relations [Abstract in Rivista]
E., Alietti; Brigatti, Maria Franca; Capedri, Silvio; Poppi, Luciano
abstract

Members of the roedderite-chayesite series in lamproites from Cancarix (SE Spain), crystallized from late magmatic residua under low PH20, high temperature (~ l l00~ oxidizing conditions. They exhibit the following main chemical variations: 0.14 ~< Na ~< 0.62 atoms per formula unit (apfu); 0.80 ~<K ~< 1.00 apfu; 2.97 ~< Mg ~< 4.33 a.pfu; 0.00 ~< Fe 2+ ~< 1.19 apfu; 0.42 ~< Fe 3+ ~< 0.87 apfu; they arehexagonal (10.120 ~< a ~< 10.135 A, 14.305 ~< c ~< 14.326 A), P6/mcc. The characteristic chemicalsubstitution is: Fe 3+ + [] ~ Fe 2+ + (K+Na) § Six crystal structures have been refined to 0.020 ~<Robs ~< 0.026. They have the osumilite/milarite-type structure, with Si entering the double tetrahedral TIsix-membered rings, and Mg and Fe entering both the ring-linking 72 tetrahedra, and the A octahedra.The 12-coordinated C site, located between two double rings of T1 tetrahedra, is occupied mainly by Kand subordinately by Na. Furthermore, Na occupies the partially empty nine-fold coordinate

1992 - Biotiti plutoniche e struttura di politipi 1M e 2M1 coesistenti. [Relazione in Atti di Convegno]
Bigi, Simona; Brigatti, Maria Franca
abstract

1992 - Biotiti ricche in bario nelle rocce basiche della zona Ivrea-Verbano [Articolo su rivista]
Bigi, Simona; Brigatti, Maria Franca
abstract

1992 - Cristallochimica ed ordinamento cationico di pseudobrookiti ed armarcoliti [Relazione in Atti di Convegno]
Brigatti, Maria Franca; S., Contini; Capedri, Silvio; Poppi, Luciano
abstract

1992 - Effect of crystal chemistry on sorption of Pb and Zn on clays and soil fraction [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1992 - Pb and Zn sorption by montmorillonite and Kaolinite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1992 - Popolazioni ottaedriche e di interstrato in miche triottaedriche 1M: considerazioni cristallochimiche [Relazione in Atti di Convegno]
Brigatti, Maria Franca
abstract

1992 - Raffinamento strutturale di Mg-chayesiti [Relazione in Atti di Convegno]
E., Alietti; Brigatti, Maria Franca; Poppi, Luciano
abstract

1992 - SYNTHESIS AND CHARACTERIZATION OF LAYERED CHLOROCADMATES(II) WITH PEROVSKITE-LIKE STRUCTURES [Articolo su rivista]
Battaglia, Lp; Corradi, Anna; Pelosi, G; Cramarossa, Mr; Manfredini, Tiziano; Pellacani, Gian Carlo; Motori, A; Saccani, A; Sandrolini, F; Brigatti, Maria Franca
abstract

The synthesis and the structural, thermal, and electrical characterization of tetrachlorocadmate(II) systems, with perovskite-like structures, are described. The countercations are diprotonated amines, such as the ethylenediamine and propane-1,3-diamine dications. The structural model of the compounds consists of layers extending to the ab plane of CdCl6 corner sharing octahedra. The holes between these layers are occupied by alkylammonium ions stabilizing the structure through hydrogen bonding. Thermal analysis shows the presence of a first-order phase transition in the propane-1,3-diammonium compound, related to the disordering of the hydrocarbon chains at high temperatures which causes a decrease in the c parameter and minor differences in the a and b parameters. The electrical conductivity of the investigated compounds is apparenly protonic and seems to increase as the distance between the layers containing the inorganic chains increases.

1991 - Biotites from Ivrea-Verbano basic complex [Abstract in Rivista]
Brigatti, Maria Franca; Bigi, Simona; Mazzucchelli, Maurizio; Rivalenti, Giorgio
abstract

1991 - Crystal chemical variations in biotites from lower crust gabbroic rocks (Ivrea zone, NW Italy) [Abstract in Rivista]
Bigi, Simona; Brigatti, Maria Franca; Mazzucchelli, Maurizio; Rivalenti, Giorgio
abstract

1991 - Crystal chemistry of Fe- and Cr-rich warwichite. [Articolo su rivista]
Bigi, Simona; Brigatti, Maria Franca; Capedri, Silvio
abstract

Warwickite is an orthorhombic oxyborate mineral with the general formula t6lM2Ot3lBOj (M : Mg2+, Mn2+, Fe3+, Ti4+, Al3+). The studied warwickite samples are from lamproitic rocks (umillites) and associated carbonatite-like veins (Jumilla, Murcia province, southeast Spain). Their chemical compositions are quite variable and different from those of warwickite described in the literature: in particular, CrrO, varies between 0.0 and 13.5 wto/0,t otal wto/oF e as FerO, is as high as 50.6 Mo/oa nd total wto/oT iO, as high as 10.2 wto/0T. wo main substitutions occur in Jumilla warwickite: Mg'* + Tia+ = 2Fe3+a nd Fe3* + Cr3+. The structures of seven crystals of different compositions were refined in space group Pnma, giving R : 0.018-0.038. The structural results show that: (l) The Ml octahedron is smaller and more distorted than the M2 octahedron. (2) Distortion of the octahedral layer is greater in Fe-rich warwickite. (3) Fe preferentially enters the Ml site. (4) The M2- 04 distance decreasesw ith increasingT i, suggestingp referential ordering at the M2 site. TEM studies show planar (100) defects. These defects cause variations in the octahedral chain length.

1991 - EFFECT OF TI SUBSTITUTION IN BIOTITE-1M CRYSTAL-CHEMISTRY [Articolo su rivista]
Brigatti, Maria Franca; Galli, Ermanno; Poppi, Luciano
abstract

Crystal structure refinements were performed on eight Ti-rich biotite-1M crystals from lamproitic rocks (Murcia and Albacete provinces, Spain), a monzonitic-alkali syenite pluton (Norway), an alkaline gabbro-peralkaline syenite association (Quebec, Canada), and a quartz diorite (Calabria, Italy). The refinements, carried out in space group C2/m, gave R values between 0.019 and 0.030. The crystals cover a Ti range from 0.29 to 1.05 atoms pfu (O + OH + F = 24) and a ratio of Mg/octahedral occupancy between 0.4 and 0.7. The structure refinements show the following: (1) In all samples the octahedral trans M1 site is larger and flatter than the cis M2 sites because of the preferential ordering of Fe plus Ti with respect to Mg. (2) The octahedral M1 site distortion increases as Ti increases and decreases as Mg/octahedral occupancy decreases. (3) For samples with Mg/octahedral occupancy > 0.5, the refined occupancies of the M1 sites show that Ti4+ substitution is balanced by octahedral vacancies; M2 sites have features similar to those in Mg end-members because of the preferential ordering of Mg. (4) Octahedral sheet thickness in (Ti,Mg)-rich biotite is smaller than that in Fe-rich biotite.

1991 - Mineralogy of Cretaceous green clay levels (Friuli Platform, Southern Alps, Italy): relationships to the depositional environment [Articolo su rivista]
Ghetti, S.; Brigatti, Maria Franca
abstract

1991 - ORIGIN OF CLAY-MINERALS IN THE BONARELLI HORIZON (UMBRIAN APENNINES, CENTRAL ITALY) [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

Chemical, thermal, X-ray and statistical analyses were carried out on the clay fraction of the Bonarelli Horizon (Umbrian region, Central Italy) in order to investigate its origin. The vertical lithological sequence (organic carbon, siliceous and clay layers of varying colour and thickness) seems to change regularly, allowing the horizon to be subdivided into five sub-horizons (A to E). Sub-horizon B is clearly distinguishable from the others on the basis of the clay fractions. The presence of organic material and authigenic sulphates, constant chemical composition within a single sub-horizon, and regular repetition of the layers, show that the Bonarelli Horizon is the result of an alternation of anoxic events in a continental margin facies. A substantial contribution of volcanoclastic material is suggested for sub-horizon B.

1990 - 1M Biotite octahedral layer [Relazione in Atti di Convegno]
Brigatti, Maria Franca
abstract

1990 - Crystal chemical variations in biotites from lower crust gabbroic rocks (Ivrea zone, NW Italy) [Abstract in Rivista]
S., Ghetti; Brigatti, Maria Franca
abstract

1990 - Crystal-structure refinements of 1M plutonic biotites. [Articolo su rivista]
Brigatti, Maria Franca; Davoli, P.
abstract

Crystal-structure refinements were performed on 5 plutonic 1M biotite crystals from the 3 main lithol. complexes (granitic, syenitic, and monzonitic) and from a rock transitional between the granite and monzonitic complexes of the same plutonic body in the Valle del Cervo (Verceli, northwestern Italy). All refinements were carried out in the space group C20m (R = 0.02-0.03 for 4 samples; R = 0.06 for 1 sample). Although the Valle de Cervo biotite samples show similar chem. compn. and crystal-chem. features, structural details as deduced from F maps suggest different orientations of OH- groups in samples from different plutonic complexes. Structural details of the biotites show that (1) octahedral-layer distortion in more Mg-rich biotites is greater (and analogous in M1 and M2 sites) than that in more Fe-rich biotites, where the "av." distortion of the octahedral layer decreases with increasing Fe content and the M1 site is more istorted and larger than the M2 site; (2) the redn. in M-O distance in the 2 octahedra causes a more marked redn. in the size of the M2 sites as compared with the M1 site; (3) octahedral geometrical parameters are affected both by their chem. compn. and by the constraints of close packing within the layer; and (4) tetrahedral-ring distortion is not affected by the octahedral compn., whereas it is linked to the geometry of the ditrigonal cavity occupied by the interlayer cation.

1990 - Ti-rich biotites: structural and crystal chemical features [Abstract in Rivista]
Brigatti, Maria Franca; Galli, Ermanno; Poppi, Luciano
abstract

1990 - Warwickites: crystal chemistry and TEM study [Abstract in Rivista]
Bigi, Simona; Brigatti, Maria Franca; Capedri, Silvio
abstract

1989 - Chemical, spettroscopic and electrical conduction properties of iodinated nickel diimine complexes [Articolo su rivista]
Lelj, F.; Morelli, G.; Ricciardi, G.; Brigatti, Maria Franca; Rosa, A.
abstract

Bis(diimine)nickelcomplexes [diimine = 2,3-diiminonaphthalene (din) and 9,10-diiminophenanthrene (dip)] have been prepared by oxidation of a solution of Ni2+ and the appropriate diamine. The complexes were studied by UV-vis spectroscopy and compared with the well-known bis(o-phenylenediimine)nickelcomplex. Oxidation with iodine gave Ni(din)2Ix and Ni(dip)2Ix (where x = 0.13–3.30). Thermogravimetric analyses (TGA) provided quantitative information on the iodine content. Weight losses at 100°C were observed for highly iodinated compounds involving the decomposition of I5− to I3− and for all species above 260°C. Raman and IR spectroscopy were used to characterize the iodine-doped complexes. The Raman spectra showed strong scattering attributable to I3− (107 cm−1) and 15− (160 cm−1), the latter only for highly iodinatedcomplexes. The conductivity of iodine-doped materials was studied by using linear two-probe (300 K) and variable temperature (77–300 K) van der Pauw methods on pressed pellets. The conductivity is thermally activated, with an apparent activation energy of 0.25 and 0.075 eV for Ni(din)2Ix and Ni(dip)2Ix, respectively. A large increase of the conductivity for more extended molecules is observed.

1989 - Crystal chemical characterization of biotites and amphiboles from metabasites (Ivrea-Verbano Zone, Italian Western Alps). [Articolo su rivista]
Bigi, Simona; Brigatti, Maria Franca
abstract

Biotites and amphiboles in metabasites from Ivrea-Verbano Zone were studied to illustrate possible correlations between their chem. compn. and the metamorphic grade (from lower to upper amphibolite- and granulite-facies) and paragenesis. The biotites examd. are intermediate in compn. between phlogopite and annite; with increasing metamorphic grade, the phlogopite end member and Ti content increase, where AlVI decreases. The crystal chem. variations of biotites in metabasites are compared with those in metapelites: Ti-tschermak type substitution mechanism prevails in upper amphibolite facies (esp. in metabasites) and in granulite-facies; the Al-tschermak substitution mechanism prevails (esp. in metapelites) in the lower amphibolite facies. Statistical anal. (multivariate anal. of variance) indicated that all variables, except those relative to interlayer cations, are highly significant in terms of metamorphic grade; however, interlayer cations other than AlIV and AlVI were the most significant variables in distinguishing between biotites of metabasites and those of metapelites. Amphiboles, in the amphibolite-facies rocks, are mainly magnesiohornblendes; those in granulite facies are pargasitic hornblendes. The A-site alkali metals and the octahedral Ti and Al are generally compensated by AlIV-Si substitution in tetrahedral position. Significant variations in metabasite amphiboles from amphibolite to granulite facies were found: Ti and alkali metals increase and Mn decreases, which is the same general pattern seen in biotites from the same area. In the case of lower and upper amphibolite facies, statistical anal. shows less marked distinction than for biotites.

1989 - Single crystal study of igneous biotite: comparison of data collection techniques [Relazione in Atti di Convegno]
G., Artioli; Brigatti, Maria Franca
abstract

1989 - The clay minerals in the "Bonarelli level" (Umbrian Apennine, Italy): evidence of their origin [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1988 - Biotiti ed anfiboli nella serie Kinzigitica (Zona Ivrea-Verbano). La Microsonda Ionica nelle Scienze della Terra [Relazione in Atti di Convegno]
Bigi, Simona; Brigatti, Maria Franca; Poppi, Luciano
abstract

1988 - Chemistry and structural order in hydrothermal and sedimentary Sardinia kaolinites [Articolo su rivista]
Brigatti, Maria Franca
abstract

Chem., thermal, x-ray analyses, and crystallinity tests were made on kaolinite samples of hydrothermal and sedimentary origin (from 2 Sardinia localities, Italy), to explore correlations among structural order, unit-cell parameter dimensions, compn., and geol. setting. The structural formulae indicate the nature and extent of various types of ionic substitution (prevalently Fe for Al in octahedral sites): the Fe content was 0.005-0.116 in sedimentary samples and 0.052-0.406 in hydrothermal ones. A good linear correlation between Fe and Cr content is shown. The variable crystallinity of these samples is linked prevalently to Fe content. A trend that links the increase in total Fe content to the decrease in the structural order is confirmed; also the temps. of thermal effects are inversely correlated to structural Fe content. The b and c unit-cell parameters increase as structural disorder (or Fe content) increases; a behaves inversely. The unit-cell parameters are affected by the trace element content; this is particularly evident if Y vs. b and c is considered. The sedimentary samples are characterized by a higher structural order than those of hydrothermal origin because of the different Fe content. Statistical anal. results (factor anal.) confirm that the structural order of kaolinites is affected by the overall geochem. of the genetic environment.

1988 - Chlorites from cobalt pyrite horizons, Upper Martello Valley (Alto Adige, Northern Italy) [Articolo su rivista]
Brigatti, Maria Franca; Casari, L.
abstract

Chlorites from volcanic-sedimentary sequences, hosting the Borromeo Co-pyrite ores in the Upper Martello Valley (Italy), occur in phyllites of upper greenschist facies. Chlorites in the ore-mineralized phyllites are chamosites with a Fe/(Fe + Mg) ratio of 0.59-0.71; 2 samples from host phyllites are clinochlore with a Fe/(Fe+Mg) ratio of ∼0.40. The IIb polytype prevails in most chlorites. The presence of the metastable Ib polytype correlate with higher Fe-content. Possible diagenetic relicts exhibited by the chlorite-Ib polytypes suggest a premetamorphic origin.

1988 - Raffinamento cristallochimico di biotiti in rocce plutoniche. La Microsonda Ionica nelle Scienze della Terra [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Davoli, Paolo
abstract

1988 - Variazioni cristallochimiche nella serie 1M flogopite-annite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Davoli, Paolo
abstract

1987 - Chemistry and structural order in hydrothermal and sedimentary kaolinites [Relazione in Atti di Convegno]
Brigatti, Maria Franca
abstract

1987 - Chlorites from cobalt-pyrite horizons - Upper Martello Valley (Alto Adige, Northern Italy).Granites and their surroundings. [Relazione in Atti di Convegno]
Brigatti, Maria Franca; L., Casari
abstract

1987 - Crystal Chemistry of Igneous Rock Biotites [Articolo su rivista]
Brigatti, Maria Franca; Gregnanin, A.
abstract

A study of 304 selected biotite analyses, with 17 chemical variables (Al IV , Fe IV , Al VI Fe VI , Mg, Mn, Ti, Li, Na, K, Rb, Ca, Ba, OH, F, Cl,fH2O and fO2 , can cause more limited variations.

1987 - Crystal chemistry of igneous rock biotites. Granites and their surroundings [Relazione in Atti di Convegno]
Brigatti, Maria Franca; A., Gregnanin
abstract

1987 - Natural and monoionic aliettite: hydration and dehydration states [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

The dehydration of an interstratified talc-trioctahedral smectite mineral (aliettite) from Monte Chiaro, Taro Valley, Italy, saturated by Na, K, Rb, Cs, Mg, Ca, Sr, Ba and NH4 cations, was studied by X-ray powder diffraction and thermal analysis, under different conditions of temperature and relative humidity. Both in the natural and exchanged states the mineral exhibited several orders of basal reflections and, to varying relative humidity (P/Po) and temperature (T) conditions, behaved like a smectite except that: (i) the c-dimension was not very sensitive to relative humidity increase; (ii) the closest packing was for T > 400~ the collapsed state being reached gradually as Tincreased and an inverse trend was apparent between 20 ~ and 300~ (iii) the endothermic reactions at T = 400~ and T = 600~ appeared to be affected by the exchange treatment. The experimental data are consistent with a structural model in which it is possible to distinguish layers containing a patchwork of talc and smectite domains: the patchworks are superposed to make a regular alternation of the two domains.

1987 - Weight of Interlayer Cations into Montmorillonite Type Differentiation [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1986 - Corrensites: genetic relationships assessed by multivariate statistical analysis [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano; Fabbri, A. G.
abstract

Corrensite (CR) [12173-14-7] is defined as 1:1 regular interstratification of trioctahedral chlorite with either trioctahedral smectite or trioctahedral vermiculite, the former constituting low-charge CR and the latter high-charge CR. A representative collection of chem. analyses is used in this paper to verify the existence of characteristic variation patterns in the chem. of hydrothermal and sedimentary CR. The data have been carefully selected from published sources. Multivariate anal. of variance and discriminant anal. are the 2 methods used in the study. The results obtained demonstrate that a relation exists between the chem. compn. of CR and the genetic environments in which the mineral formed.

1985 - 29 Angstrom interstratified minerals: crystalchemical review and genetic relationships assessed by multivariate statistical methods [Relazione in Atti di Convegno]
Alietti, Andrea; Brigatti, Maria Franca
abstract

1985 - Contribution of Infrared Spectroscopy to the Study of Corrensite [Articolo su rivista]
F., Bergaya; Brigatti, Maria Franca; J. J., Fripiat
abstract

A corrensite from Taro Valley, Italy, was studied by infrared analysis at different temperatures in the natural state and after exchange with seven different cations. The vibrational bands in the OH-stretching region can be divided into three main absorption regions: 3690-3640, 3580-3560, and 3500-3000 cm−1. The influence of the cation hydration water was observed in the third region only, whereas the intensity, frequency, and shape of the residual bands were not related to the nature of the exchangeable cations. The bands of region I were unaffected by heating the sample to 500°C; however, those in regions II and III were destroyed. Deuteration was not observed for any of the three OH-stretching regions. The dichroic behavior of the OH-stretching bands in the three regions were relatively affected by the exchangeable cations. Generally, the bands in region I exhibited a more dichroic behavior than those in regions II and III.From the IR data corrensite appears to consist of: (1) a trioctahedral silicate layer with an OH-stretching band at about 3685 cm−1, (2) a hydroxide layer with OH-stretching bands at about 3570 and 3420 cm−1, and (3) a distinct interlayer space that is not interstratified with the hydroxide layers.

1985 - Crystalchemical differences in Al-rich smectites as shown by multivariate analysis of variance and discriminant analysis [Articolo su rivista]
Alberti, Alberto; Brigatti, Maria Franca
abstract

Multivariate analysis of variance and discriminant analysis were used to establish the crystal chemistry of several Al-rich smectites. The statistical analyses were carded out on 78 samples taken from the literature which were classified on the basis of their physicochemical properties. A strong discrimination exists between beidellites and montmorillonites, ‘non-ideal’ montmorillonites and ‘ideal’ montmorillonites, and Wyoming-type and Cheto-type montmorillonites. Of the Cheto-type montmorillonites, the Tatatilla-type samples are strongly discriminated, whereas the distinction between Chambers- and Otay-types is not strong. AlIV, AlVI, Fe, Mg, and Ca are generally important discriminating variables, whereas the tetrahedral portion of the layer charge, commonly used as a discriminating factor among these minerals, is only moderately significant.

1985 - Dependence of chemistry on genesis in biotites assessed by multivariate statistical analysis [Relazione in Atti di Convegno]
Brigatti, Maria Franca; A., Gregnanin
abstract

1985 - Dependence of chemistry on genesis in zeolites: multivariate analysis of variance and discriminant analysis [Articolo su rivista]
Alberti, Alberto; Brigatti, Maria Franca
abstract

Multivariate analysis of variance and discriminant analysis were used to study the relation between genesis and chemical composition of zeolites. Three hundred and three chemical analysesfo r 10 chemicale lements( Na, K, Mg Ca, Sr, Ba, Fe3*, Al, Si, H2O) of the mineralogical families: heulandite, chabante, erionite, phillipsite and analcime, l& of hydrothermal and 139 of sedimentaryg enesisr espectivelyw ere considered.D iscriminant analysiss howeda strong chemical diflerentiation between the two geneses for all five families; 95% of the samples are classified in the right genesis by the discriminant functions. Si and Al were important discriminating factors for all the families. The discriminant weight of the other elements varied strongly in the different families. Considering genesis only, 83% of the samples are correctly classifiedb y the discriminanta nalysis.T he differenceb etweent his value and 95%oo f the samplesc orrectly classifiedw hen the familiesa re separatelye xaminedi s explained by the strong interaction between genesis and family shown by multivariate analysis of variance.O f the 10 elementsc onsideredo nly Na appearedu nrelatedt o genesis.

1985 - Interlayer water and swelling properties of natural and homoionic corrensite [Articolo su rivista]
Brigatti, Maria Franca; Poppi, L.
abstract

A corrensite-like mineral, from near Borgotaro, Parma (Taro Valley, Italy), was studied by X-ray powder diffraction (XRD) and thermal analysis at different temperatures and water vapor pressures in the natural state and after exchange with ten different cations. In the natural state the mineral is characterized by a basal reflection at ~29 fi shifting to ~24 ~ on heating and to ~32 fit by glycerol treatment. The dehydration features of the homoionic minerals show that the stability of the complex of water, compensating cation, and silicate framework depends on the electrostatic energy of the water dipolein the cation field, similarly to smectite.XRD of the exchanged mineral shows a basal reflection of -58 fi particularly in the NH4-, Rb-, and Ba-exchanged states. This value suggests a structure characterized by a regular sequence of silicate layers with different layer charge, that generally results in a c periodicity of -29 fi, but which shifts to ~ 58 fi, and perhaps higher values, because of small differences in the compensating cation layers.

1984 - "Corrensite-like minerals" in the Taro and Ceno Valleys, Italy [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

Mineralogical properties (XRD, DTG) and chemical compositions of some chlorite-smectite interlayer minerals in alteration products of ophiolitic rocks from the Northern Apennines are presented and discussed. The presence of iron hydroxides and the continuous variation in A1203 content suggest that the corrensites are intermediate stages in the process of alteration of chlorite to smectite in an environment characterized by high element mobility. A thermal test to characterize the swelling component of the interlayer species is proposed.

1984 - Analisi della varianza e analisi discriminante in mineralogia: differenza di chimismo nelle zeoliti e nelle smectiti [Relazione in Atti di Convegno]
Alberti, Alberto; Brigatti, Maria Franca
abstract

1984 - Corrensiti: relazioni genetiche stabilite mediante analisi multivariata [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Poppi, Luciano; A. G., Fabbri
abstract

1984 - Crystal chemistry of corrensite: a review [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

Statistical analyses of chemical data from the literature of corrensite minerals suggest a large compositional variability, more evident in octahedral than in tetrahedral coordination. Mg occupies 40- 80% of the octahedral sites, with A1 and Fe 2+ making up the remainder. Approximately 15-30% of the tetrahedral sites are filled by A1. Despite this compositional variability, distinct fields for the several types of mixed-layer trioctahedral chlorite/trioctahedral swelling layer are not apparent. Statistical analyses of the composition of corrensite compared with saponite, vermiculite, and chlorite suggest that corrensite is an intermediate between trioctahedral chlorite and trioctahedral smectite. If Fe/(Fe + Mg) > 50%, chlorite alone is favored, but with increasing Mg, chlorite appears to transform into corrensite and then, by iron oxidation, into trioctahedral smectite. Despite the chemical variability between corrensite, chlorite, and saponite, corrensite appears chemically to be a well-defined species. On the other hand, corrensite cannot be characterized chemically on the basis of its swelling component. Thus, the current definition of corrensite as a regular 1:1 interstratification of trioctahedral chlorite and either trioctahedral smectite or vermiculite is appropriate.

1984 - Dependence of chemistry on genesis in Zeolites: multivariate analysis of variance and discriminant analysis. [Abstract in Rivista]
Alberti, Alberto; Brigatti, Maria Franca
abstract

1984 - Differences of crystal chemistry in Al-rich smectite types: multivariate analysis of variance and discriminant analysis [Abstract in Rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1984 - Sepiolite deposits of the El-Bur, Galgudund Area, Central Somalia [Articolo su rivista]
Alietti, Andrea; Brigatti, Maria Franca; Poppi, Luciano
abstract

1983 - A crystal chemical review of the so-called "corrensite" [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1983 - A study of a natural and exchanged chlorite/smectite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Poppi, Luciano; F., Bergaya; J. J., Fripiat
abstract

1983 - Interazioni H2O-catione nella zona di interstrato delle smectiti [Relazione in Atti di Convegno]
Brigatti, Maria Franca
abstract

1983 - Relationships between composition and structure in Fe-rich smectites [Articolo su rivista]
Brigatti, Maria Franca
abstract

Chemical and erystalloehcmical properties of natural dioctahedral Fr smectites formed by weathering of basaltic rocks in the Beriei-Euganei Area, northern Italy, were investigated. It was found that: (i) the b-dimension could be correlated both to Fe3+/E ratio (~ = octahedral occupancy) and to dehydroxylation peak temperature in the range 400-600 ~ C; (ii) it is not correct to impose a total octahedral occupancy strictly equal to 2 for dioctahedral smectites; (iii) in the smectite group there is not a continuous isomorphous series as would appearon the basis of chemical features only.

1983 - Studio infrarosso della corrensite [Relazione in Atti di Convegno]
F., Bergaya; Brigatti, Maria Franca; Fripiat, J. J.
abstract

1982 - Influenza del catione di interstrato sull'ordine strutturale della corrensite [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1982 - Some Grecian montmorillonites and the crystal chemistry of the smectite family [Articolo su rivista]
Alietti, Andrea; Brigatti, Maria Franca
abstract

Montmorillonite [1318-93-0] samples from the Island of Kimolos (Greece) were studied by X-ray diffraction, chem. anal., DTA, thermogravimetric and differential thermogravimetric analyses, IR spectroscopy, and Q-mode multivariate anal. The samples are dioctahedral but Mg-rich in octahedral sites. Three have kaolinite impurities.

1982 - Vari tipi di interlaminati clorite/smectite nelle ofioliti dell’Appennino Parmense [Relazione in Atti di Convegno]
Brigatti, Maria Franca
abstract

1981 - A mathematical model to distinguisch the members of the dioctahedral smectite series [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

St atistical (Q-mode) analysis of the chemical compositions of 122 dioctahedral smectites obtained from the literature have enabled the main solid solution ranges (montmorillonite, beidellite and nontronite) to be distinguished on a triangular diagram. In the montmorillonite area, the Wyoming, Tatatilla, Otay, Chambers and Non-Ideal montmorillonite compositional ranges are identified. Certain crystallochemical features of the smectites may be correlated with different genetic environments.

1981 - Hisingerite: crystal chemistry and review [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1981 - Interlayer water and swelling properties of monoionic montmorillonites [Articolo su rivista]
DEL PENNINO, Umberto; Mazzega, Ezio; Valeri, Sergio; Alietti, Andrea; Brigatti, Maria Franca; Poppi, Luciano
abstract

The dehydration of two montmorillonites saturated by 10 different cations is investigated by X-ray spectroscopy, in different conditions of temperature and environmental relative humidity. We consider, in particular, the cation “solvatation” water and propose a model, on the basis of which we show that, in the case of the 15-Å structure the stability of the H20-cation-silicate complex depends essentially on the electrostatic energy of the water molecule dipole in the cation field. In the 12-A case, on the other hand, sometimes the energy change associated with the redistribution of the electrical charges of the cation and of the silicate seems to prevail, depending on the interlayer spacing. We also show a correlation between cationic radius and closest interlayer spacing in the conditions of extreme dehydration.

1981 - Interlayer water and swelling properties of monoionic montmorillonites [Relazione in Atti di Convegno]
Alietti, Andrea; Brigatti, Maria Franca; DEL PENNINO, Umberto; Mazzega, Ezio; Valeri, Sergio; Poppi, Luciano
abstract

1981 - Smectiti ferrifere: influenza della composizione chimica sulle proprietà fisiche [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1980 - Vari termini di interlaminati I/M nelle argille appenniniche [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1980 - Vermiculite and its relation to parent materials as revealed by chemical features [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

Mineral chem. formulas, reported in the literature and calcd. from results of chem. analyses were treated by Q-mode factor anal. to examine the compositional variability of vermiculite [1318-00-9] and its parent micas. The 3 factors accounting principally the compositional variability were (1) Mg, (2) Al + Fe3+, and (3) Fe2+ + Mn + Ti. The solid soln. ranges of the dioctahedral (fine) and trioctahedral (coarse) vermiculites, biotites, hydromicas, and phlogopites were indicated by plotting their compns. in a triangle with the vertices represented by the 3 principal factors. Although the 2 types of vermiculites can be distinguished on the triangle, they show a continuous compositional range from 1 type to the other. This probably reflects the chem. rearrangement of the vermiculite following its formation from mica. Close chem. analogy is shown of vermiculite with phlogopite but not with biotite.

1979 - A proposal for the Tortonian/Messinian boundary [Relazione in Atti di Convegno]
Colalongo, M. L.; Di Grande, A.; D'Onofrio, S.; Giannelli, L.; Iaccarino, S.; Mazzei, R.; Brigatti, Maria Franca; Romeo, M.; Rossi, Antonio; Salvatorini, G.
abstract

non disponibile

1979 - An illite/montmorillonite interlayer mineral in porphyritic rock of "Alpe di Siusi" (BZ-Italy): the chemistry of I/M interlayer minerals [Articolo su rivista]
Alietti, Andrea; Brigatti, Maria Franca; Poppi, Luciano
abstract

An Illite/Montmorillonite mineral found in a porphyritic rock ofAlpe di Siusi has an I/M ratio of 80: 20. Introducing proper chemical parameters in a Q-Mode program of sixty-six Illites and Illite/Montmorillonite from the literature suggests the possibility of distinguishing Illites from Ilfite/Montmorillonite.

1979 - Behavior of natural montmorillonites at suitable water vapor pressure [Articolo su rivista]
Alietti, Andrea; Brigatti, Maria Franca
abstract

The effect was studied of water vapor pressure on the shifting of the x-ray basal reflection d001 of montmorillonite [1318-93-0] as a function of the content of (Ca + Mg) and (Na + K) cations in the interlayer sheet. The ratio [(Na + K)/(Ca + Mg)] = 1/3, behaves as a limiting value; at this ratio <1/3, montmorillonites behave as if the interlayer space was composed of divalent cations and at >1/3 as though they were monovalent cations.

1979 - Mineralogical and petrological contribution to the study of the Falconara basin [Articolo su rivista]
Brigatti, Maria Franca; Rossi, Antonio
abstract

1979 - Mineralogical and petrologicalcontribution to the study of the Falconara basin (Sicilia - Italy) [Relazione in Atti di Convegno]
Brigatti, Maria Franca; Rossi, Antonio
abstract

1979 - Quantitative determination of gypsum in sedimentary rocks by thermal analysis [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1979 - Studio cristallochimico e comportamento termico di solfati naturali eptaidrati: II - Indagine su alcuni termini della serie dell'epsomite [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1978 - Determinazione dell’alluminio amorfo in argille appenniniche [Articolo su rivista]
Alietti, Andrea; Brigatti, Maria Franca; Poppi, Luciano
abstract

1977 - Natural Ca-rich clinoptilolites (heulandites of group 3): new data and review [Articolo su rivista]
Alietti, Andrea; Brigatti, Maria Franca; Poppi, Luciano
abstract

New min. Si/Al and max. (Ca, Mg)/(K, Na) ratios (3.78 and ∼2, resp.) were obsd. for clinoptilolite [12173-10-3] during the thermal and chem. analyses of 5 sedimentary minerals of the heulandite [1318-63-4] family. A reexamn. of published heulandite analyses demonstrates the existence of natural Ca-rich clinoptilolites.

1976 - Chronostratigraphy of the Izarorene section in the Melilla Basin (Northeastern Morocco) [Articolo su rivista]
Arias, C.; Bigazzi, G.; Bonadonna, F. P.; Morlotti, E.; Radicati di Brozolo, F.; Rio, D.; Torelli, L.; Brigatti, Maria Franca; Giuliani, O.; Tirelli, G.
abstract

1976 - Cristallochimica e caratteristiche termiche di alcune montmorilloniti italiane [Articolo su rivista]
Poppi, Luciano; Brigatti, Maria Franca
abstract

1976 - Studio cristallochimico e comportamento termico di solfati naturali eptaidrati: I - Indagine su alcuni termini della serie della melanterite [Articolo su rivista]
Brigatti, Maria Franca; Poppi, Luciano
abstract

1975 - Il comportamento termodifferenziale e termoponderale dei minerali del gruppo dell'heulandite [Articolo su rivista]
Alietti, Andrea; Brigatti, Maria Franca; Poppi, Luciano
abstract

1974 - Le sorgenti minerali di Levico-Vetriolo e Roncegno [Articolo su rivista]
Brigatti, Maria Franca; Detomaso, G.; Perna, G.; Poppi, Luciano
abstract

1971 - Le zeoliti nelle porfiriti dell'Alta Valle del Cordevole (Belluno) [Articolo su rivista]
Brigatti, Maria Franca; Gottardi, Glauco
abstract

Università degli studi di Modena e Reggio Emilia

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