Krutovite Dimensions: 5.6 x 4.9 x 3.2 cm Locality: Svornost Mine (Einigkeit Mine), Jáchymov, Karlovy Vary District, Karlovy Vary Region, Czech Republic Description: A wonderful piece of the very rare nickel arsenide krutovite, which is only found in less than a dozen localities in the world. The type locality for the species is Potucky, which is right next to Svornost in the Jachymov District in Bohemia. Pale grey krutovite can be seen on a few sides of the specimen, the light yellow mineral is unidentified, though it could just be dickite clay. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Krutovite
A cubic nickel diarsenide with trace cobalt, copper and sulfur.
Intro adapted from Wikipedia (CC BY-SA).
Krutovite is an IMA-recognized mineral species in the sulfide class, with the chemical formula NiAs₂.
It crystallizes in the cubic crystal system (space group Pa3). It is a member of the Pyrite structural group.
Key properties: Mohs hardness 5.5; Metallic. R: (400) —, (420) —, (440) 66.2, (460) 65.4, (480) —, (500) 64.0, (520) —, (540) 64.7, (560) —, (580) 65.7 luster.
IMA symbol Kru, IMA status: approved, named in 1975.
Found in Co–Ni–As sulfide veins of hydrothermal origin.
It is found associated with Nickel-skutterudite, tennantite (Jáchymov, Czech Republic); nickeline, breithauptite, löllingite, nickel-skutterudite, rammelsbergite, pararammelsbergite.
The name refers to Georgi Alekseevich Krutov (1902–1989), Professor of Mineralogy, Moscow State University, Moscow, Russia.