Willyamite

General Information:
 Chemical Formula:
(Co,Ni)SbS
 Composition:
(Molecular Weight = 212.69 gm)
Cobalt 20.78 % Co
Nickel 6.90 % Ni
Antimony 57.24 % Sb
Sulfur 15.08 % S 
 Empirical Formula:
Co0.75Ni0.25SbS
Physical Properties:
 Cleavage:
[001] Perfect
 Color:
steel gray or silver white.
 Density:
6.76
 Diaphaniety:
Opaque
 Hardness:
5.5 - Knife Blade
 Luster:
Metallic
 Streak:
grayish black
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