Tarbagataite
Tarbagataite is an IMA-recognized mineral species in the silicate class, with the chemical formula (K )CaFe²⁺₇Ti₂(Si₄O₁₂)₂O₂(OH)₅.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Astrophyllite-Astrophyllite structural group.
Key properties: Mohs hardness 3; specific gravity 3.263; Colorless to pale yellow streak; Vitreous to pearly luster; optically biaxial.
IMA symbol Tbg, IMA status: approved, named in 2010.
Found in pegmatite veins and fenite in association with alkaline granitic massifs.
It is found associated with Astrophyllite, microcline, albite, quartz, aegirine, kupletskite, zircon, thorite, xenotime, fergusonite, fersmite, euxenite-(Y), ilmenite, columbite-(Mn).
The name refers to the Tarbagatai mountain range where the Verkhnee Espe deposit that produced the first specimens is located.