ALBERT

Description: The new minerals bobcookite (IMA 2014-030), NaAl(UO 2 ) 2 (SO 4 ) 4 ·18H 2 O and wetherillite (IMA 2014-044), Na 2 Mg(UO 2 ) 2 (SO 4 ) 4 ·18H 2 O, were found in the Blue Lizard mine, San Juan County, Utah, USA, where they occur together as secondary alteration phases in association with boyleite, chalcanthite, dietrichite, gypsum, hexahydrite, johannite, pickeringite and rozenite. Bobcookite descriptive details: lime green to greenish-yellow massive veins and columnar crystals; transparent; vitreous lustre; bright greenish-white fluorescence; pale greenish yellow streak; hardness (Mohs) 21/2; brittle; conchoidal fracture; no cleavage; moderately hygroscopic; easily soluble in cold H 2 O; density calc = 2.669 g cm –3 . Optically, biaxial (–), α = 1.501(1), β = 1.523(1), = 1.536(1) (white light); 2V meas. = 78(1)°; 2V calc. = 74°; dispersion r 〈 v , moderate. Pleochroism: X colourless, Y very pale yellow-green, Z pale yellow-green; X 〈 Y 〈 Z . EDS analyses yielded the empirical formula Na 0.97 Al 1.09 (U 1.02 O 2 ) 2 (S 0.98 O 4 ) 4 (H 2 O) 18 . Bobcookite is triclinic, P 1I, a = 7.7912(2), b = 10.5491(3), c = 11.2451(8) Å, α = 68.961(5), β = 70.909(5), = 87.139(6)°, V = 812.79(8) Å 3 and Z = 1. The structure ( R 1 = 1.65% for 3580 F o 〉 4 F ) contains [(UO 2 )(SO 4 ) 2 (H 2 O)] chains linked by NaO 4 (H 2 O) 2 octahedra to form layers. Hydrogen bonds to insular Al(H 2 O) 6 octahedra and isolated H 2 O groups hold the structure together. The mineral is named for Dr Robert (Bob) B. Cook of Auburn University, Alabama, USA. Wetherillite descriptive details: pale greenish-yellow blades; transparent; vitreous lustre; white streak; hardness (Mohs) 2; brittle; two cleavages, {101I} perfect and {010} fair; conchoidal or curved fracture; easily soluble in cold H 2 O; density calc = 2.626 g cm –3 . Optically, biaxial (+), α = 1.498(1), β = 1.508(1), = 1.519(1) (white light); 2V meas. = 88(1)°, 2V calc. = 87.9°; dispersion is r 〈 v , distinct; optical orientation: Z = b, X ^ a = 54° in obtuse β; pleochroism: X colourless, Y pale yellow-green, Z pale yellow-green; X 〈 Y Z . EDS analyses yielded the empirical formula Na 1.98 (Mg 0.58 Zn 0.24 Cu 0.11 $${\mathrm{Fe}}_{0.09}^{2+}$$ ) 1.02 (U 1.04 O 2 ) 2 (S 0.98 O 4 ) 4 (H 2 O) 18 . Wetherillite is monoclinic, P 2 1 / c, a = 20.367(1), b = 6.8329(1), c = 12.903(3) Å, β = 107.879(10)°, V = 1709.0(5) Å 3 and Z = 2. The structure ( R 1 = 1.39% for 3625 F o 〉 4 F ) contains [(UO 2 )(SO 4 ) 2 (H 2 O)] sheets parallel to {100}. Edge-sharing chains of Na(H 2 O) 5 O polyhedra link adjacent uranyl sulfate sheets forming a weakly bonded three-layer sandwich. The sandwich layers are linked to one another by hydrogen bonds through insular Mg(H 2 O) 6 octahedra and isolated H 2 O groups. The mineral is named for John Wetherill (1866–1944) and George W. Wetherill (1925–2006).

Description: The new mineral belakovskiite (IMA2013-075), Na 7 (UO 2 )(SO 4 ) 4 (SO 3 OH)(H 2 O) 3 , was found in the Blue Lizard mine, Red Canyon, White Canyon district, San Juan County, Utah, USA, where it occurs as a secondary alteration phase in association with blödite, ferrinatrite, kröhnkite, meisserite and metavoltine. Crystals of belakovskiite are very pale yellowish-green hair-like fibres up to 2 mm long and usually no more than a few μm in diameter. The fibres are elongated on [100] and slightly flattened on {021}. Crystals are transparent with a vitreous lustre. The mineral has a white streak and a probable Mohs hardness of ~2. Fibres are flexible and elastic, with brittle failure and irregular fracture. No cleavage was observed. The mineral is readily soluble in cold H 2 O. The calculated density is 2.953 g cm –3 . Optically, belakovskiite is biaxial (+) with α = 1.500(1), β = 1.511(1) and = 1.523(1) (measured in white light). The measured 2V is 87.1(6)° and the calculated 2V is 88°. The mineral is non-pleochroic. The partially determined optical orientation is X a . Electron-microprobe analysis provided Na 2 O 21.67, UO 3 30.48, SO 3 40.86, H 2 O 6.45 (structure), total 99.46 wt.% yielding the empirical formula Na 6.83 (U 1.04 O 2 )(SO 4 ) 4 (S 0.99 O 3 OH)(H 2 O) 3 based on 25 O a.p.f.u. Belakovskiite is triclinic, P 1I, with a = 5.4581(3), b = 11.3288(6), c = 18.4163(13) Å, α = 104.786(7)°, β = 90.092(6)°, = 96.767(7)°, V = 1092.76(11) Å 3 and Z = 2. The eight strongest X-ray powder diffraction lines are [ d obs Å( I )( hkl )]: 8.96(35)(002), 8.46(29)(011), 5.19(100)(1I01,101,1I10), 4.66(58)(013,1I02,1I1I0,110), 3.568(37)(120,023,005,03I3), 3.057(59)(01I6,11I5,1I31), 2.930(27)(multiple) and 1.8320(29)(multiple). The structure, refined to R 1 = 5.39% for 3163 F o 〉 4 F reflections, contains [(UO 2 )(SO 4 ) 4 (H 2 O)] 6– polyhedral clusters connected via an extensive network of Na–O bonds and H bonds involving eight Na sites, three other H 2 O sites and an SO 3 OH (hydrosulfate) group. The 3-D framework, thus defined, is unique among known uranyl sulfate structures. The mineral is named for Dmitry Ilych Belakovskiy, a prominent Russian mineralogist and Curator of the Fersman Mineralogical Museum.