Belakovskiite, Na7(UO2)(SO4)4(SO3OH)(H2O)3, a new uranyl sulfate mineral from the Blue Lizard mine, San Juan County, Utah, USA. (June 2014)

• Record Type: Journal Article
• Authors: Kampf, A. R.; Plášil, J.; Kasatkin, A. V.; Marty, J.
• Is Part Of: Mineralogical magazine. Volume 78:Number 3(2014:Jun.)
• Page Start: 639
• Page End: 649
• Publication Date: 2014-06
• Subjects: belakovskiite, -- new mineral, -- uranyl sulfate, -- hydrosulfate, -- crystal structure, -- Blue Lizard mine, -- Utah, -- USA; Mineralogy -- Periodicals; Mineralogy -- Great Britain -- Periodicals; 549.05
• DOI: 10.1180/minmag.2014.078.3.12
• Languages: English
• ISSNs: 0026-461X

Abstract

Abstract: The new mineral belakovskiite (IMA2013-075), Na7 (UO2 )(SO4 )4 (SO3 OH)(H2 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 mm 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 H2 O. The calculated density is 2.953 g cm −3 . Optically, belakovskiite is biaxial (+) with α = 1.500(1), β = 1.511(1) and γ = 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 Na2 O 21.67, UO3 30.48, SO3 40.86, H2 O 6.45 (structure), total 99.46 wt.% yielding the empirical formula Na6.83 (U1.04 O2 )(SO4 )4 (S0.99 O3 OH)(H2 O)3 based on 25 O a.p.f.u. Belakovskiite is triclinic, P, with a = 5.4581(3), b = 11.3288(6), c = 18.4163(13) Å, α = 104.786(7)°, β = 90.092(6)°, γ = 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)( 01, 101, 10), 4.66(58)(013, 02, 0, 110), 3.568(37)(120, 023, 005, 0 3), 3.057(59)(0 6, 1 5, 31), 2.930(27)(multiple) and 1.8320(29)(multiple). The structure, refined to R 1 = 5.39% for 3163 F o > 4σ F reflections, contains [(UO2 )(SO4 )4 (H2 O)] 6− polyhedral clusters connected via an extensive network of Na−O bonds and H bonds involving eight Na sites, three other H2 O sites and an SO3 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.