Bariosincosite, a new hydrated barium vanadium phosphate, from the Spring Creek Mine, South Australia

Bariosincosite is a new barium vanadium phosphate hydrate from the Spring Creek Mine, near Wilmington, South Australia. The new mineral occurs as irregular clusters of pale green, very thin platey crystals up to 250 /..1macross and 2 to 5 /..1mthick. The tetragonal crystals are tabular on {001} and the other form present is {I OO}. Associated with bariosincosite are quartz, cuprite, native copper, fluorapatite, whitlockite, baryte and springcreekite, BaY~+(P04h(OH,H20k Bariosincosite appears to have formed under supergene or low-temperature late-stage hydrothermal conditions. Electron microprobe analysis yielded: BaO 23.20; SrO 4.19; CaO 0.36; Y02 31.55; Fe203 0.20; AI203 0.50; P20S 28.15; H20 13.93 (calculated). These data give an empirical formula of (BaonSr02oCao03h:LOO[(Yri.'96Alo.03Fetolh:LoOO(P04)h.4H20, calculated on the basis of two P atoms. The simplified formula is Ba(y4+OP04hAH20. The mineral is transparent with a very pale green streak, a vitreous lustre and an estimated Mohs hardness of 3. The strongest lines in the X-ray powder pattern are [dobs (lobs) (hkl)] 6.414 (20) (110, 002); 5.748 (70) (I II); 4.552 (30) U 12, 200)