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22. Structural and compositional data for childrenite from the Homolka granite, Czech Republic.

Author

Toupal, Jonas, Mauro, Daniela, Biagioni, Cristian, Zaccarini, Federica, and Gieré, Reto

Subjects
ELECTRON probe microanalysis, GRANITE, CRYSTAL structure, SPACE groups, MUSCOVITE
Abstract

Members of the childrenite–eosphorite series, ideally (Fe 1-x Mn x) AlPO 4 (OH) 2⋅ H 2 O, from the highly evolved Homolka granite, in the southern Czech Republic, were characterized using a multi-analytical approach. They occur as anhedral grains, up to ∼0.2 mm in size, associated with quartz, muscovite, albite, and K-feldspar. Tiny inclusions of probable uraninite have been observed. Backscattered electron images reveal a patchy zoning of these members of the childrenite–eosphorite series, related to an uneven distribution of Fe and Mn. On the basis of electron microprobe analysis, the average composition of the studied material is (Fe 0.68 Mn 0.28 Ca 0.03)Σ0.99 Al 0.96 (P 1.04 Si 0.01)Σ1.05 O 4.00 (OH) 2.09⋅0.91 H 2 O, thus corresponding to childrenite. Unit-cell parameters of this species are a=6.9226(9) , b=10.4081(13) , c=13.3957(17) Å. Its crystal structure was refined in the space group Cmca down to R1=0.0295 on the basis of 602 unique reflections with Fo>4σ(Fo) and 66 refined parameters. The crystal structure analysis agrees with the results of electron microprobe analysis and suggests that, in the studied material, Fe occurs in the divalent oxidation state only. Crystal structure data are also consistent with the Raman spectrum collected on the same grain that was structurally characterized, confirming the occurrence of PO 4 groups only in childrenite. [ABSTRACT FROM AUTHOR]

Published
2024
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32. The Multi-Analytical Characterization of Calcium Oxalate Phytolith Crystals from Grapevine after Treatment with Calcination.

Author

Trouvé, Gwenaëlle, Michelin, Laure, Kehrli, Damaris, Josien, Ludovic, Rigolet, Séverinne, Lebeau, Bénédicte, and Gieré, Reto

Subjects
CALCIUM oxalate, GRAPES, PHYTOLITHS, VITIS vinifera, CRYSTALS, NUCLEAR magnetic resonance spectroscopy
Abstract

Calcium oxalate phytoliths are one of the most prominent types of Ca speciation in the plant kingdom, and they store extensive amounts of carbon in crystalline form. Ca phytoliths were investigated in the root, trunk, and bark of Vitis vinifera Chasselas from a vineyard in Alsace, France. A multi-analytical approach was used, which included SEM coupled with EDX spectroscopy, XRD, XRF, TGA, and 13C-NMR spectroscopy. These techniques revealed that phytoliths are composed of crystalline calcium oxalate monohydrate (whewellite). The whewellite crystals exhibited mostly equant or short-prismatic habits in all of the three studied grapevine parts, but bipyramidal crystals also occurred. Raphide crystals were only observed in the root, where they were abundant. Instead of using wet chemical procedures to extract the mineral components from the organic parts of the biomass, a thermal treatment via calcination was chosen. The suitable temperature of calcination was determined through TGA experiments. The calcination of the biomass samples at 250 °C enhanced the amounts of Ca phytoliths in the residual chars. The thermal treatment, however, affected the appearance of the Ca oxalate crystals by producing surfaces that displayed macroporosity and by creating fractures. For calcination at both 300 °C and 350 °C, Ca oxalate lost a molecule of carbon monoxide to form Ca carbonate, and the modifications of the original crystal surfaces were more pronounced than those observed after thermal treatment at 250 °C. [ABSTRACT FROM AUTHOR]

Published
2023
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46. Response

Author

Frye, Björn C., primary, Quartucci, Caroline, additional, Rakete, Stefan, additional, Grubanovic, Aleksandar, additional, Höhne, Kerstin, additional, Mangold, Felix, additional, Gieré, Reto, additional, Müller-Quernheim, Joachim, additional, and Zissel, Gernot, additional

Published
2021
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48. Multi-scale characterization of glaucophane from Chiavolino (Biella, Italy): implications for international regulations on elongate mineral particles

Author

Vigliaturo, Ruggero, Elkassas, Sabrina M., Della Ventura, Giancarlo, Redhammer, Günther J., Ruiz-Zepeda, Francisco, O'Shea, Michael J., Dražić, Goran, Gieré, Reto, Vigliaturo, Ruggero, Elkassas, Sabrina M., Della Ventura, Giancarlo, Redhammer, Günther J., Ruiz-Zepeda, Francisco, O'Shea, Michael J., Dražić, Goran, and Gieré, Reto

Abstract

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Vigliaturo, R., Elkassas, S. M., Della Ventura, G., Redhammer, G. J., Ruiz-Zepeda, F., O'Shea, M. J., Drazic, G., & Giere, R. Multi-scale characterization of glaucophane from Chiavolino (Biella, Italy): implications for international regulations on elongate mineral particles. European Journal of Mineralogy, 33(1), (2021): 77-112, https://doi.org/10.5194/ejm-33-77-2021., In this paper, we present the results of a multi-analytical characterization of a glaucophane sample collected in the Piedmont region of northwestern Italy. Investigation methods included optical microscopy, powder X-ray diffraction, Fourier-transform infrared spectroscopy, µ-Raman spectroscopy, Mössbauer spectroscopy, electron probe microanalysis, environmental scanning electron microscopy and energy-dispersive X-ray spectroscopy, and scanning/transmission electron microscopy combined with energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy. In addition to the crystal–chemical characterization of the sample from the mesoscale to the near-atomic scale, we have also conducted an extended study on the morphology and dimensions of the mineral particles. The main finding is that studying the same particle population at different magnifications yields different results for mineral habit, dimensions, and dimensional distributions. As glaucophane may occur as an elongate mineral particle (e.g., asbestiform glaucophane occurrences in California and Nevada), the observed discrepancies therefore need to be considered when assessing potential breathability of such particles, with implications for future regulations on elongate mineral particles. While the sample preparation and particle counting methods are not directly investigated in this work, our findings suggest that different magnifications should be used when characterizing an elongate mineral particle population, irrespective of whether or not it contains asbestiform material. These results further reveal the need for developing improved regulation for elongate mineral particles. We thus propose a simple methodology to merge the datasets collected at different magnifications to provide a more complete description and a better risk evaluation of the studied particle population., This research has been supported by the Rotary Foundation (grant no. GG1640842), Javna Agencija za Raziskovalno Dejavnost RS (grant no. P2-0393), Ministry of Education, University and Research, Italy Dipartimenti di Eccellenza (ARTICOLO 1, COMMI 314-337 20 LEGGE 232/2016), and the National Institute of Environmental Health Sciences (grant nos. P30-ES013508 and P42-ES023720).

Published
2021

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