Trüstedtite
Trüstedtite is an IMA-recognized mineral species in the sulfide class, with the chemical formula Ni²⁺Ni³⁺₂Se₄.
It crystallizes in the cubic crystal system (space group Fd3m). It is a member of the Spinel structural group.
Key properties: Mohs hardness 2.5; specific gravity 6.62; Metallic. R: (400) 42.2, (420) 43.6, (440) 45.0, (460) 46.4, (480) 47.5, (500) 48.5, (520) 49.4, (540) 50.3 luster.
IMA symbol Trü, IMA status: approved, named in 1964.
Found in uranium-bearing calcite veins in sills of albite diabase in schist (Kuusamo, Finland); in stibnite-quartz-barite veins in schists (Qiongmo deposit, China).
It is found associated with Clausthalite, penroseite, sederholmite, wilkmanite, kullerudite (Kuusamo, Finland); gold, tiemannite, clausthalite, selenian famatinite, selenian gersdorffite.
In honor of Otto Trüstedt (1866–1929), Finnish mining engineer, whose work on prospecting methods lead to the discovery of the Outokumpu ore deposit, Finland.