Pale green crystal aggregates of the rare Ni mineral nickelhexahydrite from Jachymov (Jáchymov, Krušné Hory, Karlovy Vary Region, Czech Republic). Ex. Erich Laskowski collection (USA). — Photo: David Hospital · CC BY 4.0
Nickelhexahydrite
Nickelhexahydrite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Ni(SO₄)·6H₂O.
It crystallizes in the monoclinic crystal system (space group C2/c). It is a member of the Hexahydrite structural group.
Key properties: specific gravity 2.036; Vitreous luster; optically biaxial.
IMA symbol Nhhy, IMA status: approved, named in 1965.
Precipitated from mine waters in the bottom of an open-pit nickel mine, and on nickel-bearing gabbro-dolerite rocks in the oxidation zone (Noril’sk region, Russia); in shear zones in talc overlying ultramafic rocks (Lahnaslampi deposit.
It is found associated with Morenosite.
As the nickel-dominant analog of hexahydrite.