Běhounekite, U(SO.sub.4./sub.).sub.2./sub.(H.sub.2./sub.O).sub.4./sub., from Jachymov (St Joachimsthal), Czech Republic: the first natural U.sup.4+./sup. sulphate

0369630 - FZÚ 2012 RIV GB eng J - Journal Article
Plášil, J. - Fejfarová, Karla - Novák, M. - Dušek, Michal - Škoda, R. - Hloušek, J. - Čejka, J. - Majzlan, J. - Sejkora, J. - Machovič, Vladimír - Talla, D.
Běhounekite, U(SO₄)₂(H₂O)₄, from Jachymov (St Joachimsthal), Czech Republic: the first natural U⁴⁺ sulphate.
Mineralogical Magazine. Roč. 75, č. 6 (2011), s. 2739-2753. ISSN 0026-461X. E-ISSN 1471-8022
R&D Projects: GA ČR(CZ) GAP204/11/0809
Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z30460519
Keywords : uranium minerals * X-ray diffraction * crystal structure * Jana2006
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 1.321, year: 2011

Behounekite, orthorhombic U(SO4)2(H2O)4, is the first natural sulphate of U4+. It was found in the Geschieber vein, Jachymov (St Joachimsthal) ore district, Western Bohemia, Czech Republic, crystallized on the altered surface of arsenic. The crystals have a strong vitreous lustre and a grey to greenish grey streak. They are brittle with an uneven fracture and have very good cleavage along {100}. The Mohs hardness is about 2. The empirical formula of behounekite is (U0.99Y0.33)Σ1.02(SO4)1.97(H2O)4. The simplified formula is U(SO4)2(H2O)4. Behounekite is orthorhombic, space group Pnma; the crystal structure consists of layers built up from [8]-coordinate uranium atoms and sulphate tetrahedra. The eight ligands include four oxygen atoms from the sulphate groups and four oxygen atoms from the H2O molecules. Each uranium coordination polyhedron is connected via sulphate tetrahedra with other uranium polyhedra and through hydrogen bonds to the apices of sulphate tetrahedra.
Permanent Link: http://hdl.handle.net/11104/0203650