Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Geschieberite, K (sub 2) (UO (sub 2) )(SO (sub 4) ) (sub 2) (H (sub 2) O) (sub 2) , a new uranyl sulfate mineral from Jachymov

J. Plasil, J. Hlousek, A. V. Kasatkin, R. Skoda, M. Novak and J. Cejka
Geschieberite, K (sub 2) (UO (sub 2) )(SO (sub 4) ) (sub 2) (H (sub 2) O) (sub 2) , a new uranyl sulfate mineral from Jachymov
Mineralogical Magazine (February 2015) 79 (1): 205-216

Abstract

The new mineral geschieberite (IMA2014-006), K (sub 2) (UO (sub 2) )(SO (sub 4) ) (sub 2) (H (sub 2) O) (sub 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 approximately 2. The mineral is slightly soluble in cold H (sub 2) O. The calculated density is 3.259 g cm (super -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 Na (sub 2) O 0.23, K (sub 2) O 14.29, MgO 2.05, CaO 0.06, UO (sub 3) 49.51, SO (sub 3) 27.74, H (sub 2) O 6.36 (structure), total 100.24 wt.%, yielding the empirical formula (K (sub 1.72) Mg (sub 0.29) Na (sub 0.04) Ca (sub 0.01) ) (sub Sigma 2.06) (U (sub 0.98) O (sub 2) )(S (sub 0.98) O (sub 4) ) (sub 2) (H (sub 2) O) (sub 2) based on 12 O atoms per formula unit. The Raman spectrum is dominated by the symmetric stretching vibrations of UO (super 2+) (sub 2) , SO (super 2-) (sub 4) and weaker O-H stretching vibrations. Geschieberite is orthorhombic, Pna2 (sub 1) , with a = 13.7778(3), b = 7.2709(4), c = 11.5488(2) Aa, V = 1156.92(7) Aa (super 3) , Z = 4. The eight strongest powder X-ray diffraction lines are [d (sub obs) in Aa (hkl) I (sub 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 (401,1I13) 15 and 3.006 (122) 17. The structure, refined to R = 0.028 for 1882 I > 3sigma (I) reflections, contains [(UO (sub 2) )(SO (sub 4) ) (sub 2) (H (sub 2) O)] (super 2-) sheets that are based on the protasite anion topology. Sheets are stacked perpendicular to A: . Potassium atoms and one H (sub 2) O molecule are located between these sheets, providing an interlayer linkage. The remaining H (sub 2) O 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.


ISSN: 0026-461X
EISSN: 1471-8022
Coden: MNLMBB
Serial Title: Mineralogical Magazine
Serial Volume: 79
Serial Issue: 1
Title: Geschieberite, K (sub 2) (UO (sub 2) )(SO (sub 4) ) (sub 2) (H (sub 2) O) (sub 2) , a new uranyl sulfate mineral from Jachymov
Affiliation: Academy of Sciences of the Czech Republic, Institute of Physics, Prague, Czech Republic
Pages: 205-216
Published: 201502
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 44
Accession Number: 2015-061814
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 6 tables
N50°22'00" - N50°22'00", E12°55'00" - E12°55'00"
Secondary Affiliation: Russian Academy of Sciences, Fersmann Mineralogical Museum, RUS, Russian FederationMasaryk University, CZE, Czech RepublicNational Museum, CZE, Czech Republic
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201527
Close Modal

or Create an Account

Close Modal
Close Modal