Abstract:
Phosphoinnelite, an analogue of innelite with P > S, was found in agpaitic pegmatite vein cross-cutting calcite carbonatite at the Phlogopite deposit, Kovdor alkaline-ultrabasic massif, Kola Peninsula, Russia. It is associated with cancrinite (partially altered to thomsonite-Ca), orthoclase, aegirine-augite, pectolite, magnesio-arfvedsonite, golyshevite, fluorapatite, etc. It occurs as lath-like crystals up to 0.2* 1 x6 mm typically combined in bunch-, sheaf-and rosette-like aggregates. Transparent, color yellow-brown to brown, streak pale yellowish, luster vitreous on crystal faces and greasy on broken surface. Brittle, cleavage perfect on {010} and good on {100}, fracture stepped. Mohs' hardness 4.5-5. Z)(meas.) 3.82,0(calc) 3.92 g/cm3. Opticaly biaxial (+), a = 1.730, p = 1.745, у = 1.764, 2F(meas) close to 90°. Orientation: Z~c ~ 5°. Chemical composition (electron probe data), wt %: Na20 6.06, K2O0.04, CaO0.15, SrO 0.99, BaO 41.60, MgO 0.64, MnO 1.07, FqAi 1.55, A1203 0.27, Si02 17.83, ТЮ2 16.88, Nb205 0.74, P205 5.93, S03 5.29, F 0.14, -0=F2 -0.06, total 99.12. The empirical formula calculated on (Si,Al)4014 is: (Ba3.59Sr0,]3Ko.oi)z:3.73(Na2.59Mg0.2iCao.o4)i3.o4(Ti2.8oFe3+o.26Nb0.07)5:3.13[(Si3.93Alo.o7)2:4 Oh(Pi.iiSo.87)si.9807.96](02.975Fo.io)23.075- The simplified formula: Ba4Na3Ti3Si4014(P04,S04)2(0,F)3. Tricli-nic, P\ or PI. The unit cell dimensions are: a = 5.38, ft = 7.10, с = 14.76 A, a = 99.00", p = 94.94°, у = 90.14°, K=555A3, Z=\. The strongest reflections of X-ray powder diagram (d, A-I[hkl]) are: 14.5-100[001], 3.455-40[103], _3.382-35[022], 2.921-3_5[005], 2.810-40[U4], 2.683-90[200, 201], 2.133-80[2 22], 2.059-40[204, 133,221], 1.772-30[041, 127,232, 233]. The IR spectrum is given. An admixture of P substituting S is found in innelite samples from Inagli (S. Yakutia, Russia). The innelite - phosphoinnelite isomorphous series with S/P-ratio variation is discovered. The type specimen of phosphoinnelite is deposited in Fersman Minera-logical Museum of Russian Academy of Sciences, Moscow.