Yellow single crystal of the extremely rare mineral tienshanite from the type and only known locality worldwide. From: Dara-i-Pioz Glacier, Tien Shan Mountains, Districts of the Republican Subordination, Tajikistan. — Photo: David Hospital · CC BY-SA 4.0
Tienshanite
A rare borosilicate named for the Tian Shan range — nearly rock-forming at Tajikistan's Dara-i-Pioz glacier.
Intro adapted from Wikipedia (CC BY-SA).
Tienshanite is an IMA-recognized mineral species in the silicate class, with the chemical formula K(Na,K, )₉Ca₂Ba₆Mn²⁺₆Ti₆B₁₂Si₃₆O₁₁₄(O,OH,F)₁₁.
It crystallizes in the hexagonal crystal system (space group P6/m).
Key properties: Mohs hardness 6–6.5; specific gravity 3.29; Vitreous luster; optically uniaxial.
IMA symbol Tsh, IMA status: approved, named in 1967.
Found in the central portions of alkalic pegmatites in syenite.
It is found associated with Pyrochlore, astrophyllite, bafertisite, stillwellite, danburite, galena, titanite, calcite, datolite.
The name refers to the occurrence in the Tien Shan (Tien Mountains), Ta jikistan.