Ferricopiapite

General Information:
 Chemical Formula:
Fe+++2/3Fe+++4(SO4)6(OH)2·20(H2O)
 Composition:
(Molecular Weight = 1,231.32 gm)
Iron 21.17 % Fe
Hydrogen 3.44 % H 
Sulfur 15.63 % S 
Oxygen 59.77 % O 
 Empirical Formula:
Fe3+0.6666Fe3+4(SO4)6(OH)2·20(H2O)
Physical Properties:
 Cleavage:
[???] Perfect
 Color:
yellow or orange.
 Density:
2.1
 Diaphaniety:
Transparent to Translucent
 Hardness:
2.5-3 - Finger Nail-Calcite
 Luster:
Pearly
 Streak:
light yellow
More details...