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@article{1410988,
author = {Olds, Travis and Plášil, Jakub and Kampf, Antony and Škoda, Radek and Burns, Peter and Čejka, Jiří and Bourgoin, Vincent and Boulliard, JeanandClaude},
article_location = {STUTTGART},
article_number = {1},
doi = {http://dx.doi.org/10.1127/ejm/2017/0029-2586},
keywords = {gauthierite; new mineral; uranyl-oxide hydroxy-hydrate; crystal structure; topology; oxidation zone; Shinkolobwe},
language = {eng},
issn = {0935-1221},
journal = {European Journal of Mineralogy},
title = {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},
volume = {29},
year = {2017}
}
TY - JOUR
ID - 1410988
AU - Olds, Travis - Plášil, Jakub - Kampf, Antony - Škoda, Radek - Burns, Peter - Čejka, Jiří - Bourgoin, Vincent - Boulliard, Jean-Claude
PY - 2017
TI - 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
JF - European Journal of Mineralogy
VL - 29
IS - 1
SP - 129-141
EP - 129-141
PB - E SCHWEIZERBARTSCHE VERLAGSBUCHHANDLUNG
SN - 09351221
KW - gauthierite
KW - new mineral
KW - uranyl-oxide hydroxy-hydrate
KW - crystal structure
KW - topology
KW - oxidation zone
KW - Shinkolobwe
N2 - 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 >>nu). The optical orientation is X = b, Y approximate to a*, Z approximate to c (or X = b, Y<^>a=14 degrees in obtuse beta); it is pleochroic with X very pale yellow, Y and Z orange-yellow; X << 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>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).
ER -
OLDS, Travis, Jakub PLÁŠIL, Antony KAMPF, Radek ŠKODA, Peter BURNS, Jiří ČEJKA, Vincent BOURGOIN and Jean-Claude BOULLIARD. 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. \textit{European Journal of Mineralogy}. STUTTGART: E SCHWEIZERBARTSCHE VERLAGSBUCHHANDLUNG, 2017, vol.~29, No~1, p.~129-141. ISSN~0935-1221. Available from: https://dx.doi.org/10.1127/ejm/2017/0029-2586.
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