Talnakhite

General Information:
 Chemical Formula:
Cu9(Fe,Ni)8S16
 Composition:
(Molecular Weight = 1,537.43 gm)
Iron 21.79 % Fe
Copper 37.20 % Cu
Nickel 7.63 % Ni
Sulfur 33.37 % S 
 Empirical Formula:
Cu9Fe2+6Ni2S16
 IMA Status:
Approved IMA 1968
Physical Properties:
 Color:
yellow, pink, or brown.
 Density:
4.24
 Diaphaniety:
Opaque
 Luster:
Metallic
 Streak:
black
More details...