Felbertalite
Felbertalite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Cu₂Pb₆Bi₈S₁₉.
It crystallizes in the monoclinic crystal system (space group C2/m).
Key properties: Mohs hardness 3.3–3.4; specific gravity 6.948; Grayish black streak; Metallic luster; optically biaxial.
IMA symbol Fbt, IMA status: approved, named in 1999.
Found in a hydrothermal tungsten deposit in amphibolites and felsic gneisses, in discordant quartz veins (Felbertal mine, Austria); in a copper deposit in skarn.
It is found associated with Cosalite, lillianite, bismuthinite–aikinite species, cannizzarite, junoite, pavonite series species, bismuth, chalcopyrite (Felbertal mine, Austria); aikinite.
The name refers to the valley of Felbertal, Austria, in which the mineral was found.