Anorthominasragrite, V4+O (SO4) (H2O)5, a new mineral species from Temple Mountain, Emery County, Utah, USA:: Description, crystal structure and hydrogen bonding

Anorthominasragrite, V4+ O (SO4) (H2O)(5), is a new mineral species from Temple Mountain, Emery County, Utah, U.S.A. It occurs as blue-green crusts and spherical granular aggregates (up to similar to1 mm across) in a fossil (Triassic) tree; individual crystals are <0.1 mm and are intimately intergrown. Anorthominasragrite has a white streak, a vitreous luster, and no observable fluorescence under ultraviolet light. It has no cleavage or parting. The Mohs hardness is similar to1, and the calculated density is 2.12 g/cm(3). Anorthominasragrite is biaxial positive, with alpha 1.548, beta 1.555, gamma 1.574, all +/-0.002, 2V(obs.) = 86(1)degrees, 2V(calc.) = 63degrees, nonpleochroic. X Lambda c approximate to 18degrees (in beta obtuse), Y approximate to a, Z Lambda b approximate to 19degrees (in gamma obtuse). Anorthommasragrite is triclinic, space group P (1) over bar, a 7.548(3), b 7.805(2), c 7.821(3) Angstrom, alpha 79.03(4), beta 71.94(3), gamma 65.31(3)degrees, V 397.1(2) Angstrom(3), Z = 2. The strongest seven lines in the X-ray powder-diffraction pattern [d in Angstrom(I)(hkl)] are: 6.617(100)(100), 7.053(80)(010), 4.116(80)((1) over bar 10), 3.712(80)(121,002,211), 3.206(70)(221). 2.934(50)(1 (1) over bar2,(1) over bar 02), 5.314(30)(011). Chemical analysis with an electron microprobe gave VO2 33.93, SO3 30.78, H2O (calc.) 35.52, sum 100.23 wt.%; the amount of H2O was determined by crystal-structure analysis. The resulting empirical formula on the basis of 10 anions (including 5 H2O) is V-1.04 S-0.98 O-5 (H2O)(5); the end-member formula is V O (SO4) (H2O). Anorthominasragrite is the triclinic polymorph of V O (SO4) (H2O)(5). The crystal structure of anorthominasragrite was solved by direct methods and refined to an R index of 3.2% for 673 observed (\Fo\ > 5sigmaF) reflections measured with an automated four-circle X-ray diffractometer using MoKalpha X-radiation. There is one V site occupied by V4+ and surrounded by three O atoms and three (H2O) groups in an octahedral arrangement, with one short vanadyl bond (1.587 Angstrom), four similar equatorial bonds (<2.013 9 Angstrom>). and one longer V-O bond (2.253 Angstrom) trans to the vanadyl bond. The structure consists of (V(4+)phi(6)) (phi: unspecified anion) octahedra and (SO4) tetrahedra that comer-share O2- vertices to form (V4+O)(2) (H2O)(6) (SO4)(2) groups [as in bobjonesite, V4+ O (SO4) (H2O)(3)], with two additional isolated (H2O) groups.