Adolfpateraite, K(UO2)(SO4)(OH)(H2O), a new uranyl sulphate mineral from Jachymov, Czech Republic

Abstract

Adolfpateraite, monoclinic K(UO2)(SO4)(OH)(H2O), is a new supergene mineral from the Svornost mine, Jachymov ore district, Czech Republic. It forms sulfur yellow to greenish yellow crystalline aggregates, up to 2 mm in diameter. Crystals are transparent to translucent with a vitreous luster, without observable cleavage. The streak is pale yellow. The Mohs hardness is ~2. The mineral shows a green fluorescence in long-wave ultraviolet radiation. Adolfpateraite is pleochroic, with alpha = colorless and gamma = yellow (beta could not been examined). It is biaxial, with alfa = 1.597(2), gama = 1.659(2) (beta could not been measured), birefringence 0.062. The empirical chemical formula (mean of 4 electron microprobe point analyses) was calculated based on 8 O apfu and is K0.94(UO2)1.00(SO4)1.02(OH)0.90(H2O)1.00 (water content calculated). The simplified formula is K(UO2)(SO4)(OH)(H2O), requiring K2O 10.70, UO3 64.97, SO3 18.19, H2O 6.14, total 100.00 wt%. Adolfpateraite is monoclinic, space group P21/c, a = 8.0462(1), b = 7.9256(1), c = 11.3206(2) A, beta = 107.726(2), V = 687.65(2) A^3, Z = 4, and Dcalc = 4.24 g/cm3. The five strongest reflections in the X-ray powder diffraction pattern are [dobs in Angstroms (I) (hkl)]: 7.658 (76) (100), 5.386 (100) (002), 5.218 (85) (102), 3.718 (46) (021), 3.700 (37) (202). The crystal structure has been refined from single-crystal X-ray diffraction data to R1 = 0.0166 with GOF = 1.30, based on 1915 observed reflections [Iobs > 3sigma(I)]. The crystal structure consists of chains of uranyl polyhedra extended along [010], with OH located on the shared vertex between the bipyramids. The sulfate tetrahedra decorate the outer side of the chain with bridging bidentate linkages between the uranyl pentagonal bipyramids.