Eskebornite
A brassy tetragonal copper-iron selenide, usually intergrown with other selenides.
Intro adapted from Wikipedia (CC BY-SA).
Eskebornite is an IMA-recognized mineral species in the sulfide class, with the chemical formula CuFeSe₂.
It crystallizes in the tetragonal crystal system (space group P-42c). It is a member of the Chalcopyrite structural group.
Key properties: Mohs hardness 3–3.5; specific gravity 5.35; Metallic luster.
IMA symbol Ebn, grandfathered status — known before the IMA’s founding, named in 1949.
Found in low-temperature hydrothermal vein deposits.
It is found associated with Chalcopyrite, clausthalite, tiemannite, berzelianite, naumannite, umangite, geffroyite, chaméanite, uraninite, ankerite, dolomite.
The name refers to the Eskeborn adit, Tilkerode, Germany, where first discovered.