Metallic inclusions of the extremely rare nickel selenide mineral mäkinenite in a polished sample that was analyzed by the former owner of the specimen. From Kitka River Valley, Kuusamo, North Ostrobothnia, Finland. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Mäkinenite
Mäkinenite is an IMA-recognized mineral species in the sulfide class, with the chemical formula NiSe.
It crystallizes in the hexagonal crystal system (space group R3m). It is a member of the Millerite structural group.
Key properties: Mohs hardness 2.5–3; specific gravity 7.22.
IMA symbol Mkn, IMA status: approved, named in 1964.
Found in sills of albite diabase in schist, in association with low-grade uranium mineralization (Kuusamo, Finland).
It is found associated with Clausthalite, selenian melonite (Kuusamo, Finland).
The mineral was named to honor Eero Mäkinen (1886–1953), Finnish geologist, and former President of the Outokumpu Company.