Kesterite

General Information:
 Chemical Formula:
Cu2(Zn,Fe)SnS4
 Composition:
(Molecular Weight = 437.07 gm)
Zinc 11.22 % Zn
Iron 3.19 % Fe
Copper 29.08 % Cu
Tin 27.16 % Sn
Sulfur 29.35 % S 
 Empirical Formula:
Cu2Zn0.75Fe2+0.25SnS4
Physical Properties:
 Cleavage:
None
 Color:
greenish black.
 Density:
4.54 - 4.59, Average = 4.56
 Diaphaniety:
Opaque
 Hardness:
4.5 - Between Fluorite and Apatite
 Luster:
Metallic
 Streak:
black
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