Kurgantaite
Kurgantaite is an IMA-recognized mineral species in the borate class, with the chemical formula CaSrB₅O₉Cl·H₂O.
It crystallizes in the triclinic crystal system (space group P1). It is a member of the Hilgardite structural group.
Key properties: Mohs hardness 6–6.5; specific gravity 2.99; White streak; Vitreous luster; optically biaxial.
IMA symbol Kga, IMA status: approved, named in 1952.
Found in marine evaporite salt deposits and salt domes.
It is found associated with Sylvite, halite, boracite, anhydrite, gypsum, magnesite, quartz (Kazakhstan); hydroboracite, boracite, walkerite, veatchite, szaibélyite, pringleite.
The name refers to the region, Kargan-tau, Kazakhstan, that produced the first specimens.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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