Schafarzikite

General Information:
 Chemical Formula:
Fe++Sb+++2O4
 Composition:
(Molecular Weight = 363.34 gm)
Iron 15.37 % Fe
Antimony 67.02 % Sb
Oxygen 17.61 % O 
 Empirical Formula:
Fe2+Sb2O4
Physical Properties:
 Cleavage:
[110] Perfect, [200] Good
 Color:
red, reddish brown, or yellow.
 Density:
4.3
 Diaphaniety:
Opaque
 Hardness:
3.5 - Copper Penny
 Luster:
Metallic
 Streak:
yellowish brown
More details...