Analyzed polished section of the very rare thallium mineral thalfenisite from the famous Norilsk deposit in Russia. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Thalfenisite
Thalfenisite is an IMA-recognized mineral species in the sulfide class, with the chemical formula Tl₆(Fe,Ni)₂₅S₂₆Cl.
It crystallizes in the cubic crystal system. It is a member of the Djerfisherite structural group.
Key properties: specific gravity 5.26.
IMA symbol Tfn, IMA status: approved, named in 1979.
Found in pentlandite-galena-chalcopyrite ores, localized at the contact of chalcopyrite and galena and included in pentlandite.
It is found associated with Pentlandite, galena, chalcopyrite.
The name refers to the principal constituents, THALlium, FErrum for iron, NI for nickel, and Sulfur.