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Crystal structure of the uranyl-oxide mineral rameauite

Jakub Plasil, Radek Skoda, Jiri Cejka, Vincent Bourgoin and Jean-Claude Boulliard
Crystal structure of the uranyl-oxide mineral rameauite
European Journal of Mineralogy (June 2016) 28 (5): 959-967


Rameauite is a rare supergene uranyl-oxide hydroxy-hydrate mineral that forms during hydration-oxidation weathering of uraninite. On the basis of single-crystal X-ray diffraction data collected on a microfocus source, rameauite is monoclinic, space group Cc, with a = 13.9458(19), b = 14.3105(19), c = 13.8959(18) A, beta = 118.477(14) degrees , V = 2437.7(6) A (super 3) and Z = 4, with D (sub calc) = 5.467 g cm (super -3) The structure of rameauite (R = 0.060 for 1698 unique observed reflections) contains sheets of the beta -U (sub 3) O (sub 8) topology, with both UO (sub 6) and UO (sub 7) bipyramids, which is similar to the sheets found in spriggite, ianthinite and wyartite. The sheets alternate with the interlayer, which contains K (super +) , Ca (super 2+) and H (sub 2) O molecules. Interstitial cations are linked into infinite chains that extend along [10-1]. Adjacent sheets are linked through K-O, Ca-O and H-bonds. The structural formula of rameauite is K (sub 2) Ca(H (sub 2) (super [3]) O) (sub 1) (H (sub 2) (super [5]) O) (sub 4) [(UO (sub 2) ) (sub 6) O (sub 6) (OH) (sub 4) ](H (sub 2) (super [4]) O) (sub 1) The empirical formula obtained from the average of eight electron-microprobe analyses is (on the basis of 6 U p.f.u.) K (sub 1.87) (Ca (sub 1.10) Sr (sub 0.04) ) (sub Sigma 1.14) [(UO (sub 2) ) (sub 6) O (sub 6) (OH) (sub 4.15) ].6H (sub 2) O. The Raman spectrum is dominated by U-O and O-H vibrations. A discussion of related uranyl-oxide minerals is given.

ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 28
Serial Issue: 5
Title: Crystal structure of the uranyl-oxide mineral rameauite
Affiliation: Czech Academy of Sciences, Institute of Physics, Prague, Czech Republic
Pages: 959-967
Published: 20160615
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 67
Accession Number: 2016-085315
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 6 tables
Secondary Affiliation: Masaryk University, CZE, Czech RepublicNational Museum, CZE, Czech RepublicUniversite Pierre et Marie Curie, FRA, France
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201641
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