J 2015

Geschieberite, K-2(UO2)(SO4)(2)(H2O)(2), a new uranyl sulfate mineral from Jachymov

PLÁŠIL, Jakub, Jan HLOUŠEK, Anatoly KASATKIN, Radek ŠKODA, Milan NOVÁK et. al.

Basic information

Original name

Geschieberite, K-2(UO2)(SO4)(2)(H2O)(2), a new uranyl sulfate mineral from Jachymov

Authors

PLÁŠIL, Jakub (203 Czech Republic, guarantor), Jan HLOUŠEK (203 Czech Republic), Anatoly KASATKIN (643 Russian Federation), Radek ŠKODA (203 Czech Republic, belonging to the institution), Milan NOVÁK (203 Czech Republic, belonging to the institution) and Jiří ČEJKA (203 Czech Republic)

Edition

Mineralogical Magazine, Middlesex, Mineralogical Society, 2015, 0026-461X

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10500 1.5. Earth and related environmental sciences

Country of publisher

United Kingdom of Great Britain and Northern Ireland

Confidentiality degree

není předmětem státního či obchodního tajemství

Impact factor

Impact factor: 2.212

RIV identification code

RIV/00216224:14310/15:00087126

Organization unit

Faculty of Science

DOI

UT WoS

000355310100015

Keywords in English

geschieberite; new mineral; uranyl sulfate; crystal structure; Raman spectroscopy; Jachymov

Tags

Změněno: 6/4/2016 14:21, Ing. Andrea Mikešková

Abstract

V originále

The new mineral geschieberite (IMA2014-006), K-2(UO2)(SO4)(2)(H2O)(2), was found in the Svornost mine, Jachymov, Czech Republic, where it occurs as a secondary alteration phase after uraninite in association with adolfpateraite and gypsum. Geschieberite forms crystalline aggregates of bright green colour (when thick) composed of multiply intergrown prismatic crystals elongated on [001] typically reaching 0.1-0.2 mm across; observable forms are {010} and {001}. Crystals are translucent to transparent with a vitreous lustre. The mineral is brittle, with perfect cleavage on {100} and an uneven fracture. It has a greenish-white streak and a probable Mohs hardness of similar to 2. The mineral is slightly soluble in cold H2O. The calculated density is 3.259 g cm(-3). The mineral exhibits strong yellowish-green fluorescence under both shortwave and longwave UV radiation. Optically, geschieberite is biaxial (-), with beta = 1.596(2) and gamma = 1.634(4) (measured at 590 nm), with X = a. Electron-microprobe analyses provided Na2O 0.23, K2O 14.29, MgO 2.05, CaO 0.06, UO3 49.51, SO3 27.74, H2O 6.36 (structure), total 100.24 wt.%, yielding the empirical formula (K1.72Mg0.29Na0.04Ca0.01)(Sigma 2.06) (U0.98O2)(S0.98O4)(2)(H2O)(2) based on 12 O atoms per formula unit. The Raman spectrum is dominated by the symmetric stretching vibrations of UO22+, SO42- and weaker O-H stretching vibrations. Geschieberite is orthorhombic, Pna2(1), with a = 13.7778(3), b = 7.2709(4), c = 11.5488(2) angstrom, V = 1156.92(7) angstrom(3), Z = 4. The eight strongest powder X-ray diffraction lines are [d(obs) in angstrom (hkl) I-rel]: 6.882 (200) 100, 5.622 (111) 53, 4.589 (211) 12, 4.428 (202) 16, 3.681 (311) 18, 3.403 (013) 12, 3.304 (401,(1) over bar 13) 15 and 3.006 (122) 17. The structure, refined to R = 0.028 for 1882 I > 3 sigma(I) reflections, contains [(UO2)(SO4)(2)(H2O)](2-) sheets that are based on the protasite anion topology. Sheets are stacked perpendicular to a. Potassium atoms and one H2O molecule are located between these sheets, providing an interlayer linkage. The remaining H2O molecule is localized within the structural unit, at the free vertex of the uranyl pentagonal bipyramid; this vertex does not link to sulfate tetrahedra. The mineral is named for one of the most important ore veins in Jachymov - the Geschieber vein.