Graulichite-(La), LaFe3+3(AsO4)2(OH)6, a new addition to the alunite supergroup from the Patte d'Oie mine, Bou Skour mining district, Morocco
| Autor: | C. Biagioni, M. E. Ciriotti, G. Favreau, D. Mauro, F. Zaccarini |
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| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | European Journal of Mineralogy, Vol 34, Pp 365-374 (2022) |
| Druh dokumentu: | article |
| ISSN: | 0935-1221 1617-4011 |
| DOI: | 10.5194/ejm-34-365-2022 |
| Popis: | The new mineral species graulichite-(La), ideally LaFe33+(AsO4)2(OH)6, has been discovered in the Patte d'Oie mine, Bou Skour mining district, Morocco. It occurs as yellow rhombohedral crystals, up to 0.1 mm in size, with a resinous luster, associated with malachite, agardite-(La), conichalcite, and a still undetermined REE carbonate. Crystals are chemically zoned and two homogeneous domains were identified, corresponding to the empirical chemical formulae (calculated on the basis of 6 cations per formula unit, assuming the occurrence of 14 O atoms) (La0.34Ce0.20Ca0.11Sr0.07Pb0.05K0.04)Σ0.81(Fe2.163+Al0.84Cu0.20)Σ3.20(As1.23P0.39S0.37)Σ1.99O14H6.13 (domain #1) and (La0.38Ce0.22Sr0.10Ca0.09Pb0.05K0.06)Σ0.90(Fe2.603+Al0.49Cu0.20)Σ3.29(As0.91P0.50S0.40)Σ1.81O14H6.53 (domain #2). Single-crystal unit-cell parameters are a=7.252(13), c=16.77(3) Å, V=764(3) Å3, space group R-3m. The eight strongest reflections in the observed X-ray powder diffraction pattern are (d in Å, visually estimated intensity): 5.86, medium; 3.045, strong; 2.511, medium-weak; 2.239, medium; 1.960, medium-weak; 1.813, medium-weak; 1.689, medium-weak; 1.478, medium. Graulichite-(La) belongs to the dussertite group within the alunite supergroup. It is the La analogue of graulichite-(Ce) and the Fe3+ analogue of arsenoflorencite-(La). |
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