Orthominasragrite, V4+O (SO4) (H2O)(5), a new mineral species from Temple Mountain, Emery County, Utah, USA

Orthominasragrite, V4+O (SO4) (H2O)(5). is a new mineral species from Templ e Mountain, Emery County, Utah. It occurs as rounded aggregates (up to simi lar to 200 mum across) of irregular grains that are pale blue to bright blu e, depending on size. Orthominasragrite has a pale blue streak, a vitreous luster, and no observable fluorescence under ultraviolet light, It has no c leavage or parting. The Mobs hardness is similar to 1, and the calculated d ensity is 2.00 g/cm(3). Orthominasragrite is biaxial negative (pseudo-uniax ial) with alpha 1.529(2), beta 1.534(2), gamma 1.534(2), 2V(obs) = 2(4)degr ees, 2V(calc) = 0 degrees, non-pleochroic, X = b, Y = c, Z = a, Orthominasr agrite is orthorhombic. space group Pmn2(1), a 7.246(4), b 9.333(6), c 6.21 0(4) Angstrom, V420.0(3) Angstrom (3), Z= 2. The strongest seven lines in t he X-ray powder-diffraction pattern [d in Angstrom (I)(hkl)] are as follows : 4.699(10)(101,020), 3.322(5)(121), 2.865(4)(220), 2.602(3)(221,131,022), 3.734(2)(021), 3.622(2)(200), and 3.108(2)(002). Chemical analysis by elect ron microprobe gave VO2 33.88, SO3 31.97, H2O (calc.) 36.30, sum 102.15 wt. %; the proportion of H2O was determined by crystal structure analysis. The resulting empirical formula on the basis of 10 anions (including 5 H2O) is V-1.014 S-0.991 O-5 (H2O)(5) the endmember formula is VO (SO4) (H2O)(5). Or thominasragrite is the orthorhombic form of (monoclinic) minasragrite. The crystal structure was solved by direct methods and refined to an R index of 4.4% for 1007 observed (\F-o\ > 5 sigmaF) reflections measured with an aut omated four-circle X-ray diffractometer using MoK alpha X-radiation. There is one V site occupied by V4+ and surrounded by one O atom and 5 (H2O) grou ps in an octahedral arrangement, with one short apical vanadyl bond (1.580 Angstrom), four similar equatorial bonds (<2.026 Angstrom >), and one longe r V-O bond (2.231 Angstrom) trans to the vanadyl bond. The structure consis ts of isolated (V-phi6(4+)) octahedra (phi): unspecified anion) and (SO4) t etrahedra linked by hydrogen bonds.