Alwilkinsite-(Y), a new rare-earth uranyl sulfate mineral from the Blue Lizard mine, San Juan County, Utah, USA

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Publikace nespadá pod Fakultu sportovních studií, ale pod Přírodovědeckou fakultu. Oficiální stránka publikace je na webu muni.cz.
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KAMPF Antony PLÁŠIL Jakub ČEJKA Jiří MARTY Joe ŠKODA Radek LAPČÁK Ladislav

Rok publikování 2017
Druh Článek v odborném periodiku
Časopis / Zdroj Mineralogical Magazine
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
Doi http://dx.doi.org/10.1180/minmag.2016.080.139
Klíčová slova alwilkinsite-(Y); new mineral; uranyl sulfate; crystal structure; Blue Lizard mine; Utah; USA
Popis The new mineral alwilkinsite-(Y) (IMA2015-097), Y(H2O)(7)[(UO2)(3)(SO4)(2)O(OH)(3)]center dot 7H(2)O, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as a secondary alteration phase. The mineral is slightly flexible before brittle failure with splintery fracture and perfect cleavage parallel to [010], has Mohs hardness of similar to 2-2 1/2, exhibits dull greenish-grey fluorescence and has a calculated density of 3.371 g cm(-3). Alwilkinsite-(Y) occurs as yellowish-green needles, elongate on [010], with domatic terminations and exhibits the forms {102}, {301} and {12 (4) over bar}. It is optically biaxial (+) with alpha = 1.573(1), beta = 1.581(1), gamma = 1.601(1) (white light), the measured 2V is 65.3(1)degrees, the dispersion is r < nu (weak), the optical orientation is X = c, Y = a, Z = b and there is no pleochroism. Electron microprobe analyses yielded the empirical formula (Y0.66Dy0.08Gd0.06Er0.05Nd0.03Yb0.03Sm0.02Ce0.01)(Sigma 0.94) (H2O)(7) [(UO2)(3)(S1.01O4)(2)O(OH)(3)]center dot 7H(2)O. The eight strongest powder X-ray diffraction lines are [d(obs) angstrom(I)(hkl)]: 9.88(100)(101,002), 7.47(13)(102), 5.621(17)(103,201), 4.483(18)(104), 3.886(14)(130,222), 3.322(46) (multiple), 3.223(13)(multiple) and 3.145(16)(034). Alwilkinsite-(Y) is orthorhombic, P2(1)2(1)2(1), a = 11.6194(5), b = 12.4250(6), c = 19.4495(14) angstrom, V = 2807.9(3) angstrom(3) and Z = 4. The structure of alwilkinsite-(Y) (R-1 = 0.042 for 4244 F-o > 4 sigma F) contains edge-sharing chains of uranyl bipyramids with outlying sulfate tetrahedra that are similar to the chain linkages within the uranyl sulfate sheets of the zippeite structure. Short segments of the uranyl sulfate chains in the alwilkinsite-(Y) structure have the same topology as portions of the uranyl sulfate linkages in uranopilite. Alwilkinsite-(Y) is named for Alan (Al) J. Wilkins, MD (born 1955), the discoverer of the mineral.
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