Tarkianite
A rhenium sulfide from Finland's Hitura nickel mine — approved in 2003 as the first rhenium-dominant mineral.
Intro adapted from Wikipedia (CC BY-SA).
Tarkianite is an IMA-recognized mineral species in the sulfide class, with the chemical formula (Cu,Fe)(Re,Mo)₄S₈.
It crystallizes in the cubic crystal system (space group F-43m).
Key properties: Mohs hardness 5.5–6; specific gravity 7.3; Black streak; Metallic luster.
IMA symbol Trk, IMA status: approved, named in 2003.
Found in a heavy mineral concentrate derived from a serpentinized, disseminated sulfide and PGM-bearing, ultramafic intrusion.
It is found associated with Pentlandite, chromite, pyrrhotite, valleriite, chalcopyrite, cubanite, mackinawite, sperrylite, michenerite, irarsite, froodite, hollingworthite.
The mineral was named to honor Prof. Mahmud Tarkian (b. 1941) of the University of Hamburg, Germany, who earlier described an occurrence of the mineral.