Gauthierite, KPb[(UO2)(7)O-5(OH)(7)]center dot 8H(2)O, a new uranyl-oxide hydroxy-hydrate mineral from Shinkolobwe with a novel uranyl-anion sheet-topology

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F17%3A00100328" target="_blank" >RIV/00216224:14310/17:00100328 - isvavai.cz</a>

Result on the web

<a href="http://dx.doi.org/10.1127/ejm/2017/0029-2586" target="_blank" >http://dx.doi.org/10.1127/ejm/2017/0029-2586</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1127/ejm/2017/0029-2586" target="_blank" >10.1127/ejm/2017/0029-2586</a>

Result language

angličtina

Original language name

Gauthierite, KPb[(UO2)(7)O-5(OH)(7)]center dot 8H(2)O, a new uranyl-oxide hydroxy-hydrate mineral from Shinkolobwe with a novel uranyl-anion sheet-topology

Original language description

Gauthierite, KPb[(UO2)(7)O-5(OH)(7)]center dot 8H(2)O, is a new uranyl-oxide hydroxy-hydrate mineral from the Shinkolobwe Mine, Democratic Republic of Congo, Africa. It occurs on a matrix of uraninite-bearing quartz gangue associated with soddyite and a minor metazeunerite-metatorbernite series mineral. It is a product of oxidation-hydration weathering of uraninite. Gauthierite is monoclinic, P2(1)/c, with a = 29.844(2) angstrom, b = 14.5368(8) angstrom, c = 14.0406(7) angstrom, beta = 103.708(6)degrees, V = 5917.8(6) angstrom(3) and Z = 8. Prismatic crystals have pronounced lengthwise striations and reach about 1 mm in length. Gauthierite is yellowish orange with a light orange streak and vitreous lustre. The Mohs hardness is similar to 3 to 4. It is brittle with an uneven fracture and perfect cleavage on {0 1 0}. The calculated density based on the empirical formula is 5.437 g/cm(3). Optically, gauthierite is biaxial (-), with alpha = 1.780(5), beta = 1.815(5), gamma = 1.825(5) (white light), 2V(meas.) = 58(1)degrees; dispersion is extreme (r &gt;&gt;nu). The optical orientation is X = b, Y approximate to a*, Z approximate to c (or X = b, Y&lt;^&gt;a=14 degrees in obtuse beta); it is pleochroic with X very pale yellow, Y and Z orange-yellow; X &lt;&lt; Y approximate to Z. Electron microprobe analyses (average of 9) provided: K2O 1.29, PbO 7.17, UO3 82.10, H2O 8.78 (structure), total 99.34 wt.%. The empirical formula (based on 34 O a.p.f.u.) is: K0.67Pb0.78U7O34H23.77. The ideal formula is KPb[(UO2)(7)O-5(OH)(7)](H2O)(8), which requires K2O 1.90, PbO 9.00, UO3 80.74, H2O 8.35, total 100 wt.%. Raman and infrared spectral data confirm the presence of UO22+, OH- and molecular H2O. The eight strongest powder X-ray diffraction lines are [d(obs) in angstrom (hkl) I-rel]: 7.28 (020,400) 49, 3.566 (040, -802, -204) 67, 3.192 (622, -224) 100, 2.541 (-842, -244) 18, 2.043 (406) 14, 2.001 (662, -264, 14.2.0) 23, 1.962 (426, -146) 14, and 1.783 (12.0.4, -10.4.6) 17. The crystal structure of gauthierite (R = 0.0567 for 6997 reflections with [I&gt;3 sigma(I)]) contains uranyl-(hydroxo)-oxide sheets with a novel topology that is similar to that of vandendriesscheite, but with a unique chain sequence UDPDPDUPUP, P-4(UD)(6). Adjacent sheets are linked through K+ and Pb2+ cations (the lone 6s(2) pair on Pb atoms is stereoactive).

Czech name

—

Czech description

—

Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10504 - Mineralogy

Project

—

Continuities

S - Specificky vyzkum na vysokych skolach<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2017

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

European Journal of Mineralogy

ISSN

0935-1221

e-ISSN

—

Volume of the periodical

29

Issue of the periodical within the volume

1

Country of publishing house

DE - GERMANY

Number of pages

13

Pages from-to

129-141

UT code for WoS article

000396823700011

EID of the result in the Scopus database

—