Isolated crystal of the very rare borate mineral volkovskite from one of the few localities known: Satimola Salt Dome, Western Kazakhstan Province, Kazakhstan. — Photo: David Hospital · CC BY-SA 4.0
Volkovskite
Volkovskite is an IMA-recognized mineral species in the halide class, with the chemical formula KCa₄B₂₂O₃₂(OH)₁₀Cl·4H₂O.
It crystallizes in the triclinic crystal system (space group P1).
Key properties: Mohs hardness 2–2.5; specific gravity 2.27; Vitreous luster; optically biaxial.
IMA symbol Vlk, IMA status: approved, named in 1966.
Uncommon in water-insoluble residues from salt domes and potash deposits.
It is found associated with Halite, sylvite, hilgardite, boracite, anhydrite (Inder deposit, Kazakhstan).
The mineral was named to honor A.I. Volkovskaya, petrographer, who first noted the mineral.