Uranosphaerite from Horni Halze near Medenec (Krusne hory Mountains, Czech Republic): description and vibrational characteristics
Sejkora, Jiří Čejka
published: Jul 22, 2008
ArtNo. ESP154018501009, Price: 29.00 €
The rare secondary uranium mineral uranosphaerite from Horní Halže (Krušné hory Mountains, Czech Republic) was studied by X-ray diffraction, chemical-analytical and spectroscopic techniques. The most complete X-ray powder diffraction pattern for this mineral is presented here. The chemical composition, determined by electron microprobe analysis, corresponds closely to the formula of uranosphaerite Bi(UO2)O2OH. The refined unit-cell parameters (a = 7.558(1), b = 7.824(1), c = 7.699(1) Å, β = 92.90(1)°, V = 454.7(1) Å3) agree well with those of a recent crystal-structure determination. Bands in powder infrared and single-crystal Raman spectra are tentatively assigned; the Raman spectra are the first measured for this mineral. U-O bond lengths in the uranyl cation are calculated from the wavenumbers of the ν1 and ν3 UO22+ stretching vibrations. Hydrogen bonds in uranosphaerite are discussed and the corresponding O-H···O bond lengths are inferred.