DELIENSITE, FE(UO2)(2)(SO4)(2)(OH)(2)CENTER-DOT-3H(2)O, A NEW FERROUSURANYL SULFATE HYDROXYL HYDRATE FROM MAS-DALARY, LODEVE, HERAULT, FRANCE

Deliensite, ideally Fe(UO2)(2)(SO4)2(OH)(2).3H(2)O, is a new mineral s pecies from the Mas d'Alary uranium deposit, in Lodeve, Herault, Franc e. It occurs as submillimetric tabular crystals arranged in spherical aggregates, and is associated with uraninite, gypsum and pyrite. The c rystals are pale yellow to grayish white in color with a vitreous lust er, and nonfluorescent. D-meas 3.268 and D-calc 3.31 (empirical formul a), 3.26 g/cm(3) (idealized formula); H-Mobs = 2 Optically biaxial neg ative, 2V = 73(2)degrees, alpha 1.432(calc.), beta 1.470(2) and gamma 1.492(3) with optical orientation Y and Z in plane (100), and Z parall el to elongation. The dispersion r > v is weak, and the crystals are n onpleochroic. Deliensite is orthorhombic, space group Pnnm or Pnn2, wi th unit-cell parameters refined from powder data: a 15.908(5), b 16.27 4(3), c 6.903(1) Angstrom, V 1787(1) Angstrom(3), a:b:c: 0.9775:1:0.42 42, Z = 4. The crystals show a tabular habit, tenacity is weak, and th e {100} cleavage is perfect. The strongest ten reflections of the X-ra y powder-diffraction pattern [d in (Angstrom)(I)(hkl)] are: 7.95(81)(2 00), 5.90(100)(111), 4.26(31)(031), 4.20(37)(301), 3.94(71)(140), 3.45 (67)(002), 3.165(50)(202), 2.893(41)(151), 2.596(70)(142) and 2.118(27 )(033). Electron-microprobe and thermogravimetric analyses gave: FeO 7 .42, UO3 67.63, SO3 17.37, H2O 8.63, total 101.05 wt.%. The empirical formula (based on O = 13) is Fe-0.909(UO2)(2.081)(SO4)(1.919)(OH)(2.08 2).3.179 H2O. Deliensite originates from the alteration of uraninite a nd primary sulfides, with a contribution from the host rocks. The mine ral name honors Belgian mineralogist Michel Deliens. Holotype material is deposited in the mineralogical collection of the Royal Belgian Ins titute of Natural Sciences, Brussels, Belgium.