From structure topology to chemical composition. XXVIII. Titanium silicates: Jinshajiangite from the Oktyabr'skii Massif, Donetsk Region, Ukraine, a new occurrence

Abstract

ABSTRACT Here we report electron-microprobe data and unit-cell parameters for jinshajiangite, ideally NaBaFe2+4Ti2(Si2O7)2O2(OH)2F, from a new locality: the Oktyabr'skii massif in the coastal area of the Azov Sea, Donetsk region, Ukraine. Chemical analysis by electron microprobe gave Nb2O5 1.59, ZrO2 0.61, TiO2 17.07, SiO2 27.60, Al2O3 0.08, Fe2O3 2.04, FeO 16.42, BaO 9.81, ZnO 0.76, MnO 12.97, CaO 1.82, MgO 0.07, K2O 2.05, Na2O 2.51, F 2.48, H2O 1.92, O = F –1.04, sum 98.76 wt.%; H2O was determined in accord with the required number of monovalent anions for the Ti-dominant perraultite-type minerals: OH + F = 3 pfu; the Fe3+/Fe2+ ratio was assigned in accord with Mössbauer-spectroscopy results for jinshajiangite from a different locality. The empirical formula calculated on the basis of 19 (O + F) is (Na0.71Ca0.28□0.01)Σ1(Ba0.56K0.38□0.06)Σ1(Fe2+1.99Mn1.59Fe3+0.22Zn0.08Mg0.02Al0.01□0.09)Σ4 (Ti1.86Nb0.10Zr0.04)Σ2(Si4.00O14)O2[(OH)1.86F0.14]Σ2F1.00, Z = 4. Unit-cell parameters from the single-crystal data were determined by least-squares refinement of 9807 reflections with I > 10σI and are as follows: a = 10.726(8), b = 13.834(10), c = 11.065(8) Å, α = 108.172(5), β = 99.251(7), γ = 90.00(1)°, V = 1537.5(3.4) Å3, space group C .