• journal_title：The Canadian Mineralogist
• Contributor：Jakub Plášil ; Jiří Sejkora ; Jiří Čejka ; Pavel Škácha ; Viktor Goliáš ; Jana Ederová
• Publisher：Mineralogical Association of Canada
• Date：2010-
• Format：text/html
• Language：en
• Identifier：10.3749/canmin.48.1.113
• journal_abbrev：Can Mineral
• issn：0008-4476
• volume：48
• issue：1
• firstpage：113
• section：Articles

Phosphate-rich metalodèvite was found in the Jánská vein, in the Březové Hory deposit, Příbram ore district, Czech Republic. It occurs as coatings and centimeter-scale aggregates associated with metazeunerite in proximity to strongly altered uraninite in a vein of quartz and sphalerite. Powder X-ray-diffraction data for metalodèvite were indexed on the structure model reported for synthetic metakirchheimerite (space group P1), in contrast to the tetragonal cell originally proposed for metalodèvite (space group P4₂/m). The refined unit-cell parameters are: a 7.193(5), b 9.771(8), c 13.24(1) Å, α 75.54(6), β 84.07(6), γ 81.68(6)° and V 889(1) ų. The results of electron-microprobe analyses show that metalodèvite from Březové Hory contains up to 40 mol.% of the phosphate component. Such extensive substitution has not been reported previously for metalodèvite and its related phases. The thermogravimetric curve of metalodèvite exhibits several dehydration steps in the range ~20–300°C, which can be assigned to the release of molecular water, with a total weight loss of 14.70 wt.%, corresponding to 8.43 H₂O pfu. The empirical formula of the metalodèvite studied is: (Zn_0.72Fe_0.10Mg_0.06Al_0.05)_∑0.93 (UO₂)_2.12[(AsO₄)_1.44(PO₄)_0.56]_∑2.00·8.43H₂O (mean result of seven analyses, on the basis of As + P = 2 apfu). The observed content of H₂O is close to the ideal reported for the crystal structures of related octahydrates. Stretching and bending vibrations in the Raman and infrared spectra were tentatively assigned to the (UO₂)²⁺, (AsO₄)³⁻, (PO₄)³⁻ and H₂O units.