Phosphoinnelite, Ba4Na3Ti3Si4O14(PO4,SO4)2(O,F)3, a new mineral species from peralkaline pegmatite of the Kovdor pluton, Kola Peninsula

Phosphoinnelite, an analogue of innelite with P > S, has been found in a peralkaline pegmatite vein crosscutting calcite carbonatite at the phlogopite deposit, Kovdor pluton, Kola Peninsula. Cancrinite (partly replaced with thomsonite- Ca), orthoclase, aegirine- augite, pectolite, magnesioarfvedsonite, golyshevite, and fluorapatite are associated minerals. Phosphoinnelite occurs as lath- shaped crystals up to 0.2 x 1 x 6 mm in size, which are combined typically in bunch-, sheaf-, and rosettelike segregations. The color is yellow - brown, with vitreous luster on crystal faces and greasy luster on broken surfaces. The mineral is transparent. The streak is pale yellowish. Phosphoinnelite is brittle, with perfect cleavage parallel to the {010} and good cleavage parallel to the {100}; the fracture is stepped. The Mohs hardness is 4.5 to 5. Density is 3.82 g/cm(3) (meas.) and 3.92 g/cm(3) (calc.). Phosphoinnelite is biaxial (+), alpha = 1.730, beta = 1.745, and gamma = 1.764, 2V (meas.) is close to 90 degrees. Optical orientation is Z boolean AND c similar to 5 degrees. Chemical composition determined by electron microprobe is as follows (wt %): 6.06 Na2O, 0.04 K2O, 0.15 CaO, 0.99 SrO, 41.60 BaO, 0.64 MgO, 1.07 MnO, 1.55 Fe2O3, 0.27 Al2O3, 17.83 SiO2, 16.88 TiO2, 0.74 Nb2O5, 5.93 P2O5, 5.29 SO3, 0.14 F, -O=F-2 = - 0.06, total is 99.12. The empirical formula calculated on the basis of (Si, Al)(4)O-14 is (Ba3.59Sr0.13K0.01)(Sigma 3.73)(Na2.59Mg0.21Ca0.04)(Sigma 3.04)(Ti2.80Fe0.263+Nb0.07)(Sigma 3.13) [(Si3.93Al0.07)(Sigma 4)O-14 (P1.11S0.87)(Sigma 1.98)O-7.96] (O2.975F0.10)(Sigma 3.075). The simplified formula is Ba4Na3Ti3Si4O14(PO4, SO4)(2)(O, F)(3). The mineral is triclinic, space group P (1) over bar or P1. The unit cell dimensions are a = 5.38, b = 7.10, c = 14.76 angstrom; alpha = 99.00 degrees, beta = 94.94 degrees, gamma = 90.14 degrees; and V = 555 angstrom(3), Z = 1. The strongest lines of the X- ray powder pattern [d, angstrom in (I)(hkl)] are: 14.5(100)(001), 3.455(40)(103), 3.382(35)(0 (2) over bar2), 2.921(35)(005), 2.810(40)(1 (1) over bar4), 2.683(90)(200, (2) over bar 01), 2.133(80)((2) over bar(2) over bar2), 2.059(40)(204, 1 (3) over bar3, 221), 1.772(30)(0 (4) over bar1, 1 (2) over bar7, 2 (3) over bar2, 2 (3) over bar3). The infrared spectrum is demonstrated. An admixture of P substituting S has been detected in the innelite samples from the Inagli pluton (South Yakutia, Russia). An innelite - phosphoinnelite series with a variable S/P ratio has been discovered. The type material of phosphoinnelite has been deposited at the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.