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Paola Comodi
Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, 06123 Perugia, Italy

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Journal article
Published: 17 August 2021 in Crystals
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High-pressure synchrotron X-ray diffraction was carried out on a single crystal of mascagnite, compressed in a diamond anvil cell. The sample maintained its crystal structure up to ~18 GPa. The volume–pressure data were fitted by a third-order Birch–Murnaghan equation of state (BM3-EOS) yielding K0 = 20.4(7) GPa, K’0 = 6.1(2), and V0 = 499(1) Å3, as suggested by the F-f plot. The axial compressibilities, calculated with BM3-EOS, were K0a = 35(3), K’0a = 7.7(7), K0b = 10(3), K’0b = 7(1), K0c = 25(1), and K’0c = 4.3(2) The axial moduli measured using a BM2-EOS and fixing K’0 equal to 4, were K0a = 52(2), K0b = 20 (1), and K0c = 29.6(4) GPa, and the anisotropic ratio of K0a:K0b:K0c = 1:0.4:0.5. The evolution of crystal lattice and geometrical parameters indicated no phase transition until 17.6 GPa. Sulphate polyhedra were incompressible and the density increase of 30% compared to investigated pressure should be attributed to the reduction of weaker hydrogen bonds. In contrast, some of them, directed along [100], were very short at room temperature, below 2 Å, and showed a very low compressibility. This configuration explains the anisotropic compressional behavior and the lowest compressibility of the a axis.

ACS Style

Paola Comodi; Maximiliano Fastelli; Giacomo Criniti; Konstantin Glazyrin; Azzurra Zucchini. High Pressure Behavior of Mascagnite from Single Crystal Synchrotron X-ray Diffraction Data. Crystals 2021, 11, 976 .

AMA Style

Paola Comodi, Maximiliano Fastelli, Giacomo Criniti, Konstantin Glazyrin, Azzurra Zucchini. High Pressure Behavior of Mascagnite from Single Crystal Synchrotron X-ray Diffraction Data. Crystals. 2021; 11 (8):976.

Chicago/Turabian Style

Paola Comodi; Maximiliano Fastelli; Giacomo Criniti; Konstantin Glazyrin; Azzurra Zucchini. 2021. "High Pressure Behavior of Mascagnite from Single Crystal Synchrotron X-ray Diffraction Data." Crystals 11, no. 8: 976.

Journal article
Published: 05 August 2021 in Minerals
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Recent satellite observations and the deconvolution of remote sensing data have shown the existence of various carbonate minerals in different solar system bodies. Emissivity, from 403 to 803 K, and reflectance spectra at 300 and 193 K of selected carbonates minerals with different ratios of Na:Ca and water amounts were respectively collected at 3–20 μm and at 1–16 μm. All reflectance spectra show absorption features in the 1.9–2.5 and 3.4–4.0 μm areas due to overtone and a combination of CO32− and fundamental vibrational models at ≈9.09, 11.35, 7.06, and 14.7 μm. The increase of the Na:Ca ratio in anhydrous samples produces a shift of the absorption features in the 3.4–4.0 μm area toward shorter wavelengths, and the peak at 3.9 μm doubles in the presence of a CO32− oxygen group shared with two cations in minerals having more complex structures. The comparison of the bands at ≈669 and ≈794 cm−1 in the emissivity spectra collected at high temperatures indicates that around 600 K, phase transitions occurred in natrite and thermonatrite. The reflectance spectra measured at 193 K reveal a fine structure compared to spectra collected at room temperature. The comparison of laboratory results with the spectrum of Ceres’s brightest crater Occator from the Dawn mission, taken as a case study, showed how the anhydrous samples, shortite and nyerereite, studied in this work can also be hypothesized for Ceres’s surface beyond that already suggested (trona, natrite, thermonatrite).

ACS Style

Maximiliano Fastelli; Azzurra Zucchini; Paola Comodi; Alessandro Maturilli; Giulia Alemanno; Ernesto Palomba; Riccardo Piergallini. NIR-MID Reflectance and Emissivity Study at Different Temperatures of Sodium Carbonate Minerals: Spectra Characterization and Implication for Remote Sensing Identification. Minerals 2021, 11, 845 .

AMA Style

Maximiliano Fastelli, Azzurra Zucchini, Paola Comodi, Alessandro Maturilli, Giulia Alemanno, Ernesto Palomba, Riccardo Piergallini. NIR-MID Reflectance and Emissivity Study at Different Temperatures of Sodium Carbonate Minerals: Spectra Characterization and Implication for Remote Sensing Identification. Minerals. 2021; 11 (8):845.

Chicago/Turabian Style

Maximiliano Fastelli; Azzurra Zucchini; Paola Comodi; Alessandro Maturilli; Giulia Alemanno; Ernesto Palomba; Riccardo Piergallini. 2021. "NIR-MID Reflectance and Emissivity Study at Different Temperatures of Sodium Carbonate Minerals: Spectra Characterization and Implication for Remote Sensing Identification." Minerals 11, no. 8: 845.

Journal article
Published: 27 May 2021 in Sustainability
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A multi-methodic analysis was performed on five samples of fly ashes coming from different biomasses. The aim of the study was to evaluate their possible re-use and their dangerousness to people and the environment. Optical granulometric analyses indicated that the average diameter of the studied fly ashes was around 20 µm, whereas only ~1 vol% had diameters lower that 2.5 µm. The chemical composition, investigated with electron probe microanalysis, indicated that all the samples had a composition in which Ca was prevalent, followed by Si and Al. Large contents of K and P were observed in some samples, whereas the amount of potentially toxic elements was always below the Italian law thresholds. Polycyclic aromatic hydrocarbons were completely absent in all the samples coming from combustion plants, whereas they were present in the fly ashes from the gasification center. Quantitative mineralogical content, determined by Rietveld analysis of X-ray powder diffraction data, indicated that all the samples had high amorphous content, likely enriched in Ca, and several K and P minerals, such as sylvite and apatite. The results obtained from the chemo-mineralogical study performed make it possible to point out that biomass fly ashes could be interesting materials (1) for amendments in clayey soils, as a substitution for lime, to stimulate pozzolanic reactions and improve their geotechnical properties, thus, on the one hand, avoiding the need to mine raw materials and, on the other hand, re-cycling waste; and (2) as agricultural fertilizers made by a new and ecological source of K and P.

ACS Style

Paola Comodi; Azzurra Zucchini; Umberto Susta; Costanza Cambi; Riccardo Vivani; Gianluca Cavalaglio; Franco Cotana. Multi-Scale Minero-Chemical Analysis of Biomass Ashes: A Key to Evaluating Their Dangers vs. Benefits. Sustainability 2021, 13, 6052 .

AMA Style

Paola Comodi, Azzurra Zucchini, Umberto Susta, Costanza Cambi, Riccardo Vivani, Gianluca Cavalaglio, Franco Cotana. Multi-Scale Minero-Chemical Analysis of Biomass Ashes: A Key to Evaluating Their Dangers vs. Benefits. Sustainability. 2021; 13 (11):6052.

Chicago/Turabian Style

Paola Comodi; Azzurra Zucchini; Umberto Susta; Costanza Cambi; Riccardo Vivani; Gianluca Cavalaglio; Franco Cotana. 2021. "Multi-Scale Minero-Chemical Analysis of Biomass Ashes: A Key to Evaluating Their Dangers vs. Benefits." Sustainability 13, no. 11: 6052.

Journal article
Published: 11 October 2020 in Minerals
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Recent discoveries have demonstrated that the surfaces of Mars, Ceres and other celestial bodies, as well as asteroids and comets, are characterized by the presence of ammonium-bearing minerals. A careful study of remote data compared with the analyses of more accurate laboratory data might allow a better remote characterization of planetary bodies. In this paper, the reflectance spectra of some ammoniated hydrous and anhydrous salts, namely sal-ammoniac NH4Cl, larderellite (NH4)B5O7(OH)2·H2O, mascagnite (NH4)SO4, struvite (NH4)MgPO4·6H2O and tschermigite (NH4)Al(SO4)2·12H2O, were collected at 293 and at 193 K. The aim is to detect how the NH4 vibrational features are affected by the chemical and structural environment. All samples were recovered after cooling cycles and were characterized by X-ray powder diffraction. Reflectance spectra of the studied minerals show absorption features around 1.3, 1.6, 2.06, 2.14, 3.23, 5.8 and 7.27 μm, related to the ammonium group. Between them, the 2ν3 at ~1.56 μm and the ν3 + ν4 at ~2.13 μm are the most affected modes by crystal structure type, with their position being strictly related to both anionic group and the strength of the hydrogen bonds. The reflectance spectra of water-rich samples [struvite (NH4)MgPO4·6(H2O) and tschermigite (NH4)Al(SO4)2·12(H2O)] show only H2O fundamental absorption features in the area from 2 to 2.8 μm and a band from hygroscopic water at 3 μm. Thermal analyses (TA), thermal gravimetry (TG) and differential scanning calorimetry (DSC) allowed to evaluate the dehydration temperatures and the occurring phase transitions and decompositions in the analyzed samples. In almost all samples, endothermic peaks at distinct temperatures were registered associated to loss of water molecules, differently linked to the structures. Moreover, an endothermic peak at 465 K in sal-ammoniac was associated to the phase transition from CsCl to NaCl structure type.

ACS Style

Maximiliano Fastelli; Paola Comodi; Alessandro Maturilli; Azzurra Zucchini. Reflectance Spectroscopy of Ammonium Salts: Implications for Planetary Surface Composition. Minerals 2020, 10, 902 .

AMA Style

Maximiliano Fastelli, Paola Comodi, Alessandro Maturilli, Azzurra Zucchini. Reflectance Spectroscopy of Ammonium Salts: Implications for Planetary Surface Composition. Minerals. 2020; 10 (10):902.

Chicago/Turabian Style

Maximiliano Fastelli; Paola Comodi; Alessandro Maturilli; Azzurra Zucchini. 2020. "Reflectance Spectroscopy of Ammonium Salts: Implications for Planetary Surface Composition." Minerals 10, no. 10: 902.

Journal article
Published: 03 October 2020 in Icarus
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Accurate analyses of existing spacecraft data and telescopic observations are of fundamental importance to describe in detail the surface composition of icy planetary bodies, such as the icy galilean moons. However, the spectral library data to compare the remote data with planetary observations are usually restricted to small spectral ranges and collected only at room temperature. In this study, selected hydrated Mg-sulphates were studied. Emissivity and reflectance spectra were collected in the 3–20 μm and 0.25–16 μm range, respectively, with emissivity collected in the temperature range 300–673 K, and reflectance from 300 to 193 K. All samples were recovered after the heating and cooling cycles and were characterized by means X-ray powder diffraction. Rietveld refinements of the collected data were performed to evaluate the mineralogical composition of the samples before and after the thermal treatment. Both reflectance and emissivity measurements gave us information about the vibrational modes and overtones of SO4 and H2O. Moreover, the careful analysis of the collected data allowed us to study the influence of the cation substitution in the sulphate's crystal structures on the wavelength position of the SO4 vibrational modes. In particular, in simple salts [kieserite MgSO4·(H2O); hexahydrite MgSO4·6(H2O); gypsum CaSO4·2(H2O); thenardite Na2SO4; arcanite K2SO4; anhydrite CaSO4; barite BaSO4], the increase of the cation's radius gives a shift of the ν3 overtone towards higher wavenumbers, varying in the range 1880–2300 cm−1. On the other hand, it was observed that, in hydrated sulphates, that the increase of the strength of the hydrogen bond gives a shift of the ν3(SO4) overtones towards lower wavenumbers. At high temperature, the depth of several absorption bands in the emissivity spectra increases; however, when total or partial de-hydration occurs, a discontinuity in the deepening is observed due to the endothermic character of the dehydration phenomena. Among the investigated samples, several hydrated and anhydrous sulphates undergo de-hydration and/or phase transition at specific temperature conditions. This leads to the stabilization of new crystal structures with higher density compared to the low temperature hydrated ones. The likely occurrence of minerals dehydration will strongly affect the availability of free water in planetary depths and, as a consequence, the thickness of the icy crust. Likewise, the density changes between the different polymorphs will affect the buoyancy. This means that the structural behavior of the “non-icy” components of the icy crust have a significant impact on the structure and dynamics of the planetary bodies and have to be considered in planetological models.

ACS Style

P. Comodi; M. Fastelli; A. Maturilli; T. Balic-Zunic; A. Zucchini. Emissivity and reflectance spectra at different temperatures of hydrated and anhydrous sulphates: A contribution to investigate the composition and dynamic of icy planetary bodies. Icarus 2020, 355, 114132 .

AMA Style

P. Comodi, M. Fastelli, A. Maturilli, T. Balic-Zunic, A. Zucchini. Emissivity and reflectance spectra at different temperatures of hydrated and anhydrous sulphates: A contribution to investigate the composition and dynamic of icy planetary bodies. Icarus. 2020; 355 ():114132.

Chicago/Turabian Style

P. Comodi; M. Fastelli; A. Maturilli; T. Balic-Zunic; A. Zucchini. 2020. "Emissivity and reflectance spectra at different temperatures of hydrated and anhydrous sulphates: A contribution to investigate the composition and dynamic of icy planetary bodies." Icarus 355, no. : 114132.

Journal article
Published: 20 August 2019 in Minerals
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Ultramafic soils are characterized by severe edaphic conditions induced by a low content of essential nutrients, an adverse Ca/Mg ratio, a low water-holding capacity, and high contents of geogenic potentially toxic elements (PTEs), in particular Cr, Ni, and Co. These metals commonly exceed the content limits set by environmental agencies and governments, representing serious environmental risks for ecosystems and human health. In alpine environments, ultramafic soils are characterized by modest thickness and poor horizon differentiation. Several studies on ultramafic soils have shown that their properties may be directly related to the characteristics of the parent rocks, but most of these studies deal with soil chemistry, metal availability, isotopic composition, and pedological characterization. The aim of this research is to investigate how much the geotectonic characteristics of ultramafic bedrocks, such as the degree of serpentinization, metamorphic imprint, and deformation, may affect the mineralogical and chemical variations of ultramafic soils, including the occurrence and potential mobility of the PTEs. Using a multiscale and multi-analytical approach, we fully characterize the properties and mineralogical composition of soil profiles with different ultramafic parent rocks, i.e., partially serpentinized peridotite, massive serpentinites, and foliated serpentinites, sampled within the Voltri Massif High Pressure–Low Temperature (HP–LT) metaophiolite (Western Alps, Italy). Our results, related to soils located at comparable latitude, altitude, landscape position, and pedological environment, outline that the degree of serpentinization, the metamorphic imprint, and the deformation history of the ultramafic parent rocks are key factors influencing soil evolution, mineralogy, and chemistry, as well as PTEs distribution and mobility. Moreover, this study shows that the high content of Cr, Ni, and Co in the studied ultramafic soils has to be considered of geogenic origin and highlights the need for new approaches and methods to obtain indications on the potential contamination of natural or anthropogenic soils.

ACS Style

Pietro Marescotti; Paola Comodi; Laura Crispini; Lara Gigli; Azzurra Zucchini; Silvia Fornasaro. Potentially Toxic Elements in Ultramafic Soils: A Study from Metamorphic Ophiolites of the Voltri Massif (Western Alps, Italy). Minerals 2019, 9, 502 .

AMA Style

Pietro Marescotti, Paola Comodi, Laura Crispini, Lara Gigli, Azzurra Zucchini, Silvia Fornasaro. Potentially Toxic Elements in Ultramafic Soils: A Study from Metamorphic Ophiolites of the Voltri Massif (Western Alps, Italy). Minerals. 2019; 9 (8):502.

Chicago/Turabian Style

Pietro Marescotti; Paola Comodi; Laura Crispini; Lara Gigli; Azzurra Zucchini; Silvia Fornasaro. 2019. "Potentially Toxic Elements in Ultramafic Soils: A Study from Metamorphic Ophiolites of the Voltri Massif (Western Alps, Italy)." Minerals 9, no. 8: 502.

Journal article
Published: 02 June 2019 in Materials
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A new technology was tested to improve the cooking efficiency of the raw mixture for Portland clinker production by the use of nano-Ca(OH)2. A decrease in the free lime concentration after the firing of approximately 35% and 55% in the nano-added clinkers burned at 1350 °C and 1450 °C, respectively, with respect to the standard Portland clinkers was observed. Moreover, in the nano-added clinkers, a slight decrease in alite (C3S), of approximately 2-4 wt%, and increase in belite (C2S), of approximately 5-6 wt%, were observed. Despite these variations, the C2S and C3S abundance lies within the ranges for standard Portland clinkers. The results showed that the nano-addition leads to an increase of the raw mixtures' cooking efficiency. The relatively low energy required for the clinker firing could be used to increase the plant productivity and decrease the CO2 emissions during clinker burning. The decrease of the work index of the clinkers produced by the use of the nano-Ca(OH)2 also contributes to the energy saving during clinker grinding. Differences were also found in the pore size distribution among nano-added clinkers and the standard Portland clinker. The smallest porosities with the modal volume lying in the class of 3∙10-6 mm3 were found to increase by the use of nano-Ca(OH)2. However, the pore volumes higher than 2.0∙10-5 mm3 decreased in the nano-added clinkers.

ACS Style

Azzurra Zucchini; Paola Comodi; Alessandro Di Michele; Riccardo Vivani; Lucia Mancini; Gabriele Lanzafame; Serena Casagrande; Silvia Gentili; Francesco Vetere; Luca Bartolucci; Gianluca Polidori; Fabio Santinelli; Alessandro Neri. Effect of the Nano-Ca(OH)2 Addition on the Portland Clinker Cooking Efficiency. Materials 2019, 12, 1787 .

AMA Style

Azzurra Zucchini, Paola Comodi, Alessandro Di Michele, Riccardo Vivani, Lucia Mancini, Gabriele Lanzafame, Serena Casagrande, Silvia Gentili, Francesco Vetere, Luca Bartolucci, Gianluca Polidori, Fabio Santinelli, Alessandro Neri. Effect of the Nano-Ca(OH)2 Addition on the Portland Clinker Cooking Efficiency. Materials. 2019; 12 (11):1787.

Chicago/Turabian Style

Azzurra Zucchini; Paola Comodi; Alessandro Di Michele; Riccardo Vivani; Lucia Mancini; Gabriele Lanzafame; Serena Casagrande; Silvia Gentili; Francesco Vetere; Luca Bartolucci; Gianluca Polidori; Fabio Santinelli; Alessandro Neri. 2019. "Effect of the Nano-Ca(OH)2 Addition on the Portland Clinker Cooking Efficiency." Materials 12, no. 11: 1787.

Journal article
Published: 18 April 2019 in Crystals
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High-pressure single-crystal synchrotron X-ray diffraction data for galenobismutite, PbBi2S4 collected up to 20.9 GPa, were fitted by a third-order Birch-Murnaghan equation of state, as suggested by a FE-fE plot, yielding V0 = 697.4(8) Å3, K0 = 51(1) GPa and K’ = 5.0(2). The axial moduli were M0a = 115(7) GPa and Ma’ = 28(2) for the a axis, M0b = 162(3) GPa and Mb’ = 8(3) for the b axis, M0c = 142(8) GPa and Mc’ = 26(2) for the c axis, with refined values of a0, b0, c0 equal to 11.791(7) Å, 14.540(6) Å 4.076(3) Å, respectively, and a ratio equal to M0a:M0b:M0c = 1.55:1:1.79. The main structural changes on compression were the M2 and M3 (occupied by Bi, Pb) movements toward the centers of their respective trigonal prism bodies and M3 changes towards CN8. The M1 site, occupied solely by Bi, regularizes the octahedral form with CN6. The eccentricities of all cation sites decreased with compression testifying for a decrease in stereochemical expression of lone electron pairs. Galenobismutite is isostructural with calcium ferrite CaFe2O4, the suggested high pressure structure can host Na and Al in the lower mantle. The study indicates that pressure enables the incorporation of other elements in this structure, increasing its potential significance for mantle mineralogy.

ACS Style

Paola Comodi; Azzurra Zucchini; Tonci Balić-Žunić; Michael Hanfland; Ines Collings. The High Pressure Behavior of Galenobismutite, PbBi2S4: A Synchrotron Single Crystal X-ray Diffraction Study. Crystals 2019, 9, 210 .

AMA Style

Paola Comodi, Azzurra Zucchini, Tonci Balić-Žunić, Michael Hanfland, Ines Collings. The High Pressure Behavior of Galenobismutite, PbBi2S4: A Synchrotron Single Crystal X-ray Diffraction Study. Crystals. 2019; 9 (4):210.

Chicago/Turabian Style

Paola Comodi; Azzurra Zucchini; Tonci Balić-Žunić; Michael Hanfland; Ines Collings. 2019. "The High Pressure Behavior of Galenobismutite, PbBi2S4: A Synchrotron Single Crystal X-ray Diffraction Study." Crystals 9, no. 4: 210.

Journal article
Published: 12 September 2018 in Engineering Geology
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An extensive experimental multi-scale analysis was developed on a pyroclastic soil, coming from Central Italy, to investigate the link between the mineralogical and microstructural evolution of the system and the mechanical improvements induced by lime treatment. Chemo-mineralogical and microstructural evolution of the hydrated lime-soil system was monitored by means of Thermo-Gravimetric Analysis, 29Si Nuclear Magnetic Resonance, X-Ray Diffraction, Mercury Intrusion Porosimetry and Scanning Electron Microscopy. Rietvield analysis of X-Ray Diffraction results allowed a quantitative evaluation of amorphous phase and mineralogical components over time. Compressibility properties were measured by means of oedometer tests on raw and treated specimens. Amorphous phase plays a fundamental role in the development of pozzolanic reactions and in the formation of new cementitious compounds, whereas the contribution of zeolites, abundant in the raw soil, and other minerals is negligible. Formation of new phases induces microstructural modifications of the system, mainly detected within 28 days of curing. Chemo-mineralogical evolution of the system and the microstructural modifications affect the macroscopic behaviour of lime treated samples towards a structured behaviour, with a decrease of compressibility and an increase of yield stress.

ACS Style

Giulia Guidobaldi; Costanza Cambi; Manuela Cecconi; Paola Comodi; Dimitri Deneele; Michaël Paris; Giacomo Russo; Enza Vitale; Azzurra Zucchini. Chemo-mineralogical evolution and microstructural modifications of a lime treated pyroclastic soil. Engineering Geology 2018, 245, 333 -343.

AMA Style

Giulia Guidobaldi, Costanza Cambi, Manuela Cecconi, Paola Comodi, Dimitri Deneele, Michaël Paris, Giacomo Russo, Enza Vitale, Azzurra Zucchini. Chemo-mineralogical evolution and microstructural modifications of a lime treated pyroclastic soil. Engineering Geology. 2018; 245 ():333-343.

Chicago/Turabian Style

Giulia Guidobaldi; Costanza Cambi; Manuela Cecconi; Paola Comodi; Dimitri Deneele; Michaël Paris; Giacomo Russo; Enza Vitale; Azzurra Zucchini. 2018. "Chemo-mineralogical evolution and microstructural modifications of a lime treated pyroclastic soil." Engineering Geology 245, no. : 333-343.

Journal article
Published: 01 September 2018 in European Journal of Mineralogy
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The crystal structure of chalcostibite α-CuSbS2 was investigated at pressures between 0 and 13.2 GPa by synchrotron single-crystal X-ray diffraction, compressing the sample under neon in a diamond anvil cell. The volume-pressure data, collected up to 10.7 GPa, were fitted to a third-order Birch-Murnaghan Equation-of-State (EoS), yielding V0 = 332.4(4)Å3, K0 = 49(3) GPa, and K' = 6.9 (9). The compressibilities of the lattice parameters, up to 10.7 GPa, were calculated by fitting the data to a second-order Birch- Murnaghan EoS for a and b axes and the following values were found: K0a = 49.0(6) GPa, a0 = 6.02(2)Å, K0b = 76 (3) GPa, b0 = 3.80 (8)Å. For the c axis a third-order Birch-Murnaghan EoS was used yielding to : K0c = 33 (3) GPa, K’ = 15(2), c0 = 14.51(1)Å. At pressures higher than 11 GPa the evolution of the crystal lattice and geometrical parameters of the crystal structure indicate a phase transition from an orthorhombic Pnma to a monoclinic P21 structure. The single crystal survives the reversible phase transition despite the contraction of the unit cell of 2.2 vol% and the anisotropic change of the lattice parameters, which affects mainly the a lattice parameter. The lone electron pair stereo-chemical activity of Sb decreases with pressure as was evaluated by the reduction of the coordination-polyhedron eccentricity. The crystal structure of the high pressure β-CuSbS2 was refined in the acentric P21 space group. Pressure induces shear planes in the crystal structure. The coordination number of Cu increases from four (tetrahedral) to five (square pyramidal). At the same time, the Sb coordination changes towards a distorted octahedral with a strong reduction of the stereochemical activity of Sb lone-electron pair and a movement of its centre closer to the Sb nucleus.

ACS Style

Paola Comodi; Francesco Guidoni; Sabrina Nazzareni; Tonci Balić-Žunić; Azzurra Zucchini; Emil Makovicky; Vitali Prakapenka. A high-pressure phase transition in chalcostibite, CuSbS2. European Journal of Mineralogy 2018, 30, 491 -505.

AMA Style

Paola Comodi, Francesco Guidoni, Sabrina Nazzareni, Tonci Balić-Žunić, Azzurra Zucchini, Emil Makovicky, Vitali Prakapenka. A high-pressure phase transition in chalcostibite, CuSbS2. European Journal of Mineralogy. 2018; 30 (3):491-505.

Chicago/Turabian Style

Paola Comodi; Francesco Guidoni; Sabrina Nazzareni; Tonci Balić-Žunić; Azzurra Zucchini; Emil Makovicky; Vitali Prakapenka. 2018. "A high-pressure phase transition in chalcostibite, CuSbS2." European Journal of Mineralogy 30, no. 3: 491-505.

Journal article
Published: 29 May 2017 in European Journal of Mineralogy
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ACS Style

Azzurra Zucchini; Mauro Prencipe; Donato Belmonte; Paola Comodi. Ab initio study of the dolomite to dolomite-II high-pressure phase transition. European Journal of Mineralogy 2017, 29, 227 -238.

AMA Style

Azzurra Zucchini, Mauro Prencipe, Donato Belmonte, Paola Comodi. Ab initio study of the dolomite to dolomite-II high-pressure phase transition. European Journal of Mineralogy. 2017; 29 (2):227-238.

Chicago/Turabian Style

Azzurra Zucchini; Mauro Prencipe; Donato Belmonte; Paola Comodi. 2017. "Ab initio study of the dolomite to dolomite-II high-pressure phase transition." European Journal of Mineralogy 29, no. 2: 227-238.

Journal article
Published: 01 March 2017 in Icarus
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ACS Style

Paola Comodi; Vincenzo Stagno; Azzurra Zucchini; Yingwei Fei; Vitali Prakapenka. The compression behavior of blödite at low and high temperature up to ∼10 GPa: Implications for the stability of hydrous sulfates on icy planetary bodies. Icarus 2017, 285, 137 -144.

AMA Style

Paola Comodi, Vincenzo Stagno, Azzurra Zucchini, Yingwei Fei, Vitali Prakapenka. The compression behavior of blödite at low and high temperature up to ∼10 GPa: Implications for the stability of hydrous sulfates on icy planetary bodies. Icarus. 2017; 285 ():137-144.

Chicago/Turabian Style

Paola Comodi; Vincenzo Stagno; Azzurra Zucchini; Yingwei Fei; Vitali Prakapenka. 2017. "The compression behavior of blödite at low and high temperature up to ∼10 GPa: Implications for the stability of hydrous sulfates on icy planetary bodies." Icarus 285, no. : 137-144.

Journal article
Published: 23 March 2016 in European Journal of Mineralogy
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ACS Style

Tonči Balić-Žunić; Renie Birkedal; Anna Katerinopoulou; Paola Comodi. Dehydration of blödite, Na2Mg(SO4)2(H2O)4, and leonite, K2 Mg(SO4)2(H2O)4. European Journal of Mineralogy 2016, 28, 33 -42.

AMA Style

Tonči Balić-Žunić, Renie Birkedal, Anna Katerinopoulou, Paola Comodi. Dehydration of blödite, Na2Mg(SO4)2(H2O)4, and leonite, K2 Mg(SO4)2(H2O)4. European Journal of Mineralogy. 2016; 28 (1):33-42.

Chicago/Turabian Style

Tonči Balić-Žunić; Renie Birkedal; Anna Katerinopoulou; Paola Comodi. 2016. "Dehydration of blödite, Na2Mg(SO4)2(H2O)4, and leonite, K2 Mg(SO4)2(H2O)4." European Journal of Mineralogy 28, no. 1: 33-42.

Journal article
Published: 02 February 2016 in American Mineralogist
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Ferri-kaersutite, ideally NaCa2(Mg3TiFe3+)(Si6Al2)O22O2, is a new oxo-amphibole from Harrow Peaks, Northern Victoria Land, Antarctica. It occurs as brown prismatic crystals, up to 200 μm in length, with a vitreous luster, and a perfect {110} cleavage. Ferri-kaersutite is associated with forsterite, diopside, and Cr-bearing spinel. Chemical analyses, by a combination of electron microprobe, SIMS, and 57Fe Mössbauer spectroscopy, gave the following results (in wt%): SiO2 41.69, TiO2 5.30, Al2O3 13.65, Cr2O3 0.09, Fe2O3 4.52, MgO 15.54, CaO 11.03, MnO 0.11, FeO 2.83, Na2O 2.88, K2O 0.96, H2O 0.70, F 0.24, Cl 0.08, O=(F,Cl) −0.12, sum 99.50. On the basis of 24 anions per formula unit, the formula is (Na0.816K0.179)∑0.995(Ca1.726Fe2+0.258Mn0.014)∑1.998(Mg3.383Fe2+0.088Ti0.582Fe3+0.497Al0.439Cr0.011)∑5.00 (Si6.089Al1.911)∑8.00O22[O1.187(OH)0.682F0.111Cl0.020]∑2.00. Ferri-kaersutite is monoclinic with space group C2/m. Its unit-cell parameters are a = 9.8378(8), b = 18.0562(9), c = 5.3027(4) Å, β = 105.199(9)°, V = 908.99(13) Å3, Z = 2. The five strongest reflections in its X-ray powder diffraction pattern [d in Å (relative visual intensity, hkl)] are: 8.4 (s, 110), 3.379 (ms, 131), 3.115 (ms, 310), 2.707 (s, 151), 2.598 (ms, 061). The crystal structure of ferri-kaersutite has been refined on the basis of 1783 observed reflections [Fo > 4σ(Fo)] with a final R1 = 0.038. The relatively large equivalent isotropic displacement parameter at M(1), with respect to those at M(2) and M(3) sites, together with the short M(1)–O(3) distance, suggest the occurrence of Ti4+ at the M(1) site, whereas the small octahedral distortion at this site suggests a low Fe3+ occupancy. This element is mainly hosted at the M(2) and M(3) sites. The occurrence of amphiboles in the magma source region is notably relevant. The melting of Ti-rich amphibole in the lithosphere and subsequent degrees of melt/host peridotite reactions are able to produce melts that account for the compositional spectrum ranging from extreme alkaline lavas to the most common alkaline basalts. In particular, when this amphibole is formed by reaction between a peridotite matrix and metasomatic melts/fluids with high Fe3+/Fetot ratio, its subsequent melting can influence primary volatile contents and ultimately magma rheology.

ACS Style

Silvia Gentili; Costanza Bonadiman; Cristian Biagioni; Paola Comodi; Marco Pasero; Catherine McCammon. Ferri-kaersutite, NaCa 2 (Mg 3 TiFe 3+ )(Si 6 Al 2 )O 22 O 2 , a new oxo-amphibole from Harrow Peaks, Northern Victoria Land, Antarctica. American Mineralogist 2016, 101, 461 -468.

AMA Style

Silvia Gentili, Costanza Bonadiman, Cristian Biagioni, Paola Comodi, Marco Pasero, Catherine McCammon. Ferri-kaersutite, NaCa 2 (Mg 3 TiFe 3+ )(Si 6 Al 2 )O 22 O 2 , a new oxo-amphibole from Harrow Peaks, Northern Victoria Land, Antarctica. American Mineralogist. 2016; 101 (2):461-468.

Chicago/Turabian Style

Silvia Gentili; Costanza Bonadiman; Cristian Biagioni; Paola Comodi; Marco Pasero; Catherine McCammon. 2016. "Ferri-kaersutite, NaCa 2 (Mg 3 TiFe 3+ )(Si 6 Al 2 )O 22 O 2 , a new oxo-amphibole from Harrow Peaks, Northern Victoria Land, Antarctica." American Mineralogist 101, no. 2: 461-468.

Journal article
Published: 09 September 2015 in Mineralogy and Petrology
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Amphiboles are the most widespread hydrous metasomatic phases in spinel-bearing mantle peridotites from Harrow Peaks (HP), Northern Victoria Land (Antarctica). They occur both in veinlets and disseminated in the peridotite matrix (preferentially associated with clinopyroxene and spinel grains). Four amphibole crystals were investigated by single-crystal X-ray diffraction (SC-XRD), electron microprobe analysis (EMPA), secondary ion mass spectrometry (SIMS) and micro-Mössbauer spectroscopy; these crystal-chemical data allow to constrain upper mantle conditions during growth of these amphiboles and the role of volatile circulation during metasomatic processes in the Antarctic region. The HP amphiboles have low Mg# values (69.3–84.1), high TiO2 (2.74–5.30 wt%) and FeOtot contents (3.40 to 6.90 wt%). The Fe3+/Fetot ratios are significantly high (0.53–0.66). The W-site is mainly occupied by O2- (0.984–1.187 apfu) plus OH (H2O: 0.70–1.01 wt%) and minor F (0.04–0.24 wt%) and Cl (0.03–0.08 wt%). Consequently, HP amphiboles are actually characterized by a significant oxo component. The aH2O values were calculated at 1.5 GPa by dehydration equilibrium equations written as H2O-buffering equilibria among end-member components of amphibole and coexisting peridotite phases. Three out of four HP amphibole-bearing peridotites have values of aH2O ranging from 0.122 to 0.335; whereas one sample has aH2O remarkably higher (0.782) approaching an ideal H2O basalt solubility. The HP fO2 values, determined by the olivine-spinel-orthopyroxene oxygeobarometer (ΔQFM = −1.77 : +0.01), are remarkably different from those calculated on the basis of the amphibole dehydration equilibrium and the application of the dissociation reaction (ΔQFM = −2.60 : +6.8). The high aH2O and the extremely high fO2 values, determined by the oxy-amphibole equilibrium with respect to the redox conditions recorded by the co-existing anhydrous minerals (close to QFM buffer), revealed that: i) the amphibole-forming reaction is a relatively recent process with the new phases far from having reached a potential equilibrium with the peridotite matrix; ii) amphibole seems to be formed by the precipitation of migrating H2O-rich melts with a negligible contribution of the peridotite system.

ACS Style

S. Gentili; C. Bonadiman; Cristian Biagioni; Paola Comodi; M. Coltorti; A. Zucchini; L. Ottolini. Oxo-amphiboles in mantle xenoliths: evidence for H2O-rich melt interacting with the lithospheric mantle of Harrow Peaks (Northern Victoria Land, Antarctica). Mineralogy and Petrology 2015, 109, 741 -759.

AMA Style

S. Gentili, C. Bonadiman, Cristian Biagioni, Paola Comodi, M. Coltorti, A. Zucchini, L. Ottolini. Oxo-amphiboles in mantle xenoliths: evidence for H2O-rich melt interacting with the lithospheric mantle of Harrow Peaks (Northern Victoria Land, Antarctica). Mineralogy and Petrology. 2015; 109 (6):741-759.

Chicago/Turabian Style

S. Gentili; C. Bonadiman; Cristian Biagioni; Paola Comodi; M. Coltorti; A. Zucchini; L. Ottolini. 2015. "Oxo-amphiboles in mantle xenoliths: evidence for H2O-rich melt interacting with the lithospheric mantle of Harrow Peaks (Northern Victoria Land, Antarctica)." Mineralogy and Petrology 109, no. 6: 741-759.

Journal article
Published: 01 May 2015 in Tectonophysics
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S. Gentili; Paola Comodi; Costanza Bonadiman; M. Coltorti. Mass balance vs Rietveld refinement to determine the modal composition of ultramafic rocks: The case study of mantle peridotites from Northern Victoria Land (Antarctica). Tectonophysics 2015, 650, 144 -155.

AMA Style

S. Gentili, Paola Comodi, Costanza Bonadiman, M. Coltorti. Mass balance vs Rietveld refinement to determine the modal composition of ultramafic rocks: The case study of mantle peridotites from Northern Victoria Land (Antarctica). Tectonophysics. 2015; 650 ():144-155.

Chicago/Turabian Style

S. Gentili; Paola Comodi; Costanza Bonadiman; M. Coltorti. 2015. "Mass balance vs Rietveld refinement to determine the modal composition of ultramafic rocks: The case study of mantle peridotites from Northern Victoria Land (Antarctica)." Tectonophysics 650, no. : 144-155.

Journal article
Published: 19 December 2014 in European Journal of Mineralogy
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Silvia Gentili; Paola Comodi; Sabrina Nazzareni; Azzurra Zucchini. The Orvieto-Bagnoregio Ignimbrite: pyroxene crystal-chemistry and bulk phase composition of pyroclastic deposits, a tool to identify syn- and post-depositional processes. European Journal of Mineralogy 2014, 26, 743 -756.

AMA Style

Silvia Gentili, Paola Comodi, Sabrina Nazzareni, Azzurra Zucchini. The Orvieto-Bagnoregio Ignimbrite: pyroxene crystal-chemistry and bulk phase composition of pyroclastic deposits, a tool to identify syn- and post-depositional processes. European Journal of Mineralogy. 2014; 26 (6):743-756.

Chicago/Turabian Style

Silvia Gentili; Paola Comodi; Sabrina Nazzareni; Azzurra Zucchini. 2014. "The Orvieto-Bagnoregio Ignimbrite: pyroxene crystal-chemistry and bulk phase composition of pyroclastic deposits, a tool to identify syn- and post-depositional processes." European Journal of Mineralogy 26, no. 6: 743-756.

Journal article
Published: 01 July 2014 in Physics and Chemistry of Minerals
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Synchrotron single-crystal X-ray diffraction experiments at high-pressure and high-temperature conditions were performed up to 20 GPa and 573.0(2) K on a fully ordered stoichiometric dolomite and a partially disordered stoichiometric dolomite [order parameter, s = 0.26(6)]. The ordered dolomite was found to be stable up to approximately 14 GPa at ambient temperature and up to approximately 17 GPa at T = 573.0(2) K. The P–V data from the ambient temperature experiments were analysed by a second-order Birch–Murnaghan equation-of-state giving K 0 = 92.7(9) GPa for the ordered dolomite and K 0 = 92.5(8) GPa for the disordered dolomite. The high-temperature data, collected for the ordered sample, were fitted by a third-order Birch–Murnaghan equation-of-state resulting in K 0 = 95(6) GPa and K′ = 2.6(7). In order to compare the three experiments results, a third-order Birch–Murnaghan equation-of-state was also calculated for the ambient temperature experiments giving K 0 = 93(3) GPa, K′ = 3.9(6) for the ordered dolomite and K 0 = 92(3) GPa, K′ = 4.0(4) for the disordered dolomite. The derived axial moduli show that dolomite compresses very anisotropically, being the c-axis approximately three times more compressible than the a-axis. The axial compressibility increases as T increases, and the a-axis is the most temperature-influenced axis. On the contrary, axial compressibility is not influenced by disordering. Structural refinements at different pressures show that Ca and Mg octahedra are almost equally compressible in the ordered dolomite with K(CaO6) = 109(4) GPa and K(MgO6) = 103(3) GPa. On the contrary, CaO6 compressibility is reduced and MgO6 compressibility is increased in the disordered crystal structure where K(CaO6) = 139(4) GPa and K(MgO6) = 89(4) GPa. Disordering is found to increase CaO6 and to decrease MgO6 bond strengths, thus making stiffer the Ca octahedron and softer the Mg octahedron. Cation polyhedra are distorted in both ordered and disordered dolomites and they increase in regularity as P increases. Ordered dolomite approaches regularity at approximately 14 GPa. The increase in regularity of octahedra in the disordered dolomite is strongly affected by the very slow regularization of MgO6 with respect to CaO6. The phase transition to the high-pressure polymorph of dolomite (dolomite-II), which is driven by a significant increase in the regularity of both cations polyhedra and mineral crystal structure, occurs in the ordered dolomite at ambient temperature at approximately 14 GPa; whereas no clear evidences of phase transition were observed as regards the disordered crystal structure.

ACS Style

Azzurra Zucchini; Paola Comodi; Sabrina Nazzareni; Michael Hanfland. The effect of cation ordering and temperature on the high-pressure behaviour of dolomite. Physics and Chemistry of Minerals 2014, 41, 783 -793.

AMA Style

Azzurra Zucchini, Paola Comodi, Sabrina Nazzareni, Michael Hanfland. The effect of cation ordering and temperature on the high-pressure behaviour of dolomite. Physics and Chemistry of Minerals. 2014; 41 (10):783-793.

Chicago/Turabian Style

Azzurra Zucchini; Paola Comodi; Sabrina Nazzareni; Michael Hanfland. 2014. "The effect of cation ordering and temperature on the high-pressure behaviour of dolomite." Physics and Chemistry of Minerals 41, no. 10: 783-793.

Journal article
Published: 20 May 2014 in GEOCHEMICAL JOURNAL
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Francesco Frondini; Azzurra Zucchini; Paola Comodi. Water-rock interactions and trace elements distribution in dolomite aquifers: The Sassolungo and Sella systems (Northern Italy). GEOCHEMICAL JOURNAL 2014, 48, 231 -246.

AMA Style

Francesco Frondini, Azzurra Zucchini, Paola Comodi. Water-rock interactions and trace elements distribution in dolomite aquifers: The Sassolungo and Sella systems (Northern Italy). GEOCHEMICAL JOURNAL. 2014; 48 (3):231-246.

Chicago/Turabian Style

Francesco Frondini; Azzurra Zucchini; Paola Comodi. 2014. "Water-rock interactions and trace elements distribution in dolomite aquifers: The Sassolungo and Sella systems (Northern Italy)." GEOCHEMICAL JOURNAL 48, no. 3: 231-246.

Journal article
Published: 05 March 2014 in Contributions to Mineralogy and Petrology
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Amphibole is the hydrous metasomatic phase in spinel-bearing mantle xenoliths from Baker Rocks, Northern Victoria Land, Antarctica. It occurs in veins or in disseminated form in spinel lherzolites. Both types derive from reaction between metasomatic melts and the pristine paragenesis of the continental lithospheric mantle beneath Northern Victoria Land. To determine the effective role of water circulation during the metasomatic process and amphibole formation, six amphibole samples were fully characterized. Accurate determination of the site population and the state of dehydrogenation in each of these amphiboles was carried out using single-crystal X-ray diffraction, electron microprobe and secondary ion mass spectroscopy on the same single crystal. The Fe3+/ΣFe ratio was determined by X-ray absorption near edge spectroscopy on amphibole powder. The degree of dehydrogenation determined by SIMS is 0.870–0.994 O3(O2−) a.p.f.u., primary and ascribed to the Ti-oxy component of the amphibole, as indicated by atom site populations; post-crystallization H loss is negligible. Estimates of aH2O (0.014–0.054) were determined from the dehydration equilibrium among end-member components assuming that amphiboles are in equilibrium with the anhydrous peridotitic phases. A difference up to 58 % in determination of aH2O can be introduced if the chemical formula of the amphiboles is calculated based on 23 O a.p.f.u. without knowing the effective amount of dehydrogenation. The oxygen fugacity of the Baker Rocks amphibole-bearing mantle xenoliths calculated based upon the dissociation constant of water (by oxy-amphibole equilibrium) is between −2.52 and −1.32 log units below the fayalite–magnetite–quartz (FMQ) buffer. These results are systematically lower and in a narrow range of values relative to those obtained from anhydrous olivine–orthopyroxene–spinel equilibria (fO2 between −1.98 and −0.30 log units). A comparative evaluation of the two methods suggests that when amphibole is present in mantle peridotites, the application of oxy-amphibole equilibrium is preferred, because ol–opx–sp oxy-calibrations are not “sensitive” enough in recording the effects (if any) of amphibole in the peridotite matrix. Amphibole acts as the main H acceptor among the peridotite minerals and may prevent fluid circulation and buffer oxygen fugacity. The important conclusion of this study is that amphibole within the lithospheric mantle does not always means high water activity and oxidizing conditions.

ACS Style

C. Bonadiman; S. Nazzareni; M. Coltorti; Paola Comodi; Gabriele Giuli; Barbara Faccini. Crystal chemistry of amphiboles: implications for oxygen fugacity and water activity in lithospheric mantle beneath Victoria Land, Antarctica. Contributions to Mineralogy and Petrology 2014, 167, 1 -17.

AMA Style

C. Bonadiman, S. Nazzareni, M. Coltorti, Paola Comodi, Gabriele Giuli, Barbara Faccini. Crystal chemistry of amphiboles: implications for oxygen fugacity and water activity in lithospheric mantle beneath Victoria Land, Antarctica. Contributions to Mineralogy and Petrology. 2014; 167 (3):1-17.

Chicago/Turabian Style

C. Bonadiman; S. Nazzareni; M. Coltorti; Paola Comodi; Gabriele Giuli; Barbara Faccini. 2014. "Crystal chemistry of amphiboles: implications for oxygen fugacity and water activity in lithospheric mantle beneath Victoria Land, Antarctica." Contributions to Mineralogy and Petrology 167, no. 3: 1-17.