Voltaite

General Information:
 Chemical Formula:
K2Fe++5Fe+++3Al(SO4)12·18H2O
 Composition:
(Molecular Weight = 2,028.99 gm)
Potassium 3.85 % K 
Aluminum 1.33 % Al
Iron 22.02 % Fe
Hydrogen 1.79 % H 
Sulfur 18.96 % S 
Oxygen 52.04 % O 
 Empirical Formula:
K2Fe2+5Fe3+3Al(SO4)12·18(H2O)
 Name Origin:
Named after the Italian physicist, A. G. A. A. Volta (1745-1841).
Physical Properties:
 Cleavage:
None
 Color:
greenish black, dark green, olive green, or black.
 Density:
2.6 - 2.8, Average = 2.7
 Diaphaniety:
Opaque
 Habits:
Massive - Granular - Common texture observed in granite and other igneous rock., Crystalline - Fine - Occurs as well-formed fine sized crystals.,
 Hardness:
3-3.5 - Calcite-Copper Penny
 Luminescence:
None.
 Luster:
Silky
 Streak:
grayish green
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