Cuprokalininite
Cuprokalininite is an IMA-recognized mineral species in the sulfide class, with the chemical formula Cu(Cr³⁺Cr⁴⁺)S₄.
It crystallizes in the cubic crystal system (space group Fd-3m). It is a member of the Spinel structural group.
Key properties: Mohs hardness 4.5–5; specific gravity 4.16; Black streak; Submetallic luster.
IMA symbol Ckal, IMA status: approved, named in 2010.
Occurs as disseminated inclusions in quartz from Cr-V-bearing quartz-diopside granulite facies metamorphic rocks.
It is found associated with Cr-V-tremolite and mica, calcite, Cr-V spinels, V-titanite, pyrite, plagioclase, a mineral of the natalyite-kosmochlor series, goldmanite-uvarovite.
The name refers to its essential copper content and structural identity with kalininite, ZnCr2S4.