Rankachite

General Information:
 Chemical Formula:
CaFe++V+++++4W++++++8O36·12(H2O)
 Composition:
(Molecular Weight = 2,562.65 gm)
Calcium 1.56 % Ca
Vanadium 7.95 % V 
Iron 2.18 % Fe
Hydrogen 0.94 % H 
Tungsten 57.39 % W 
Oxygen 29.97 % O 
 Empirical Formula:
CaFe2+V5+4W8O36·12(H2O)
 IMA Status:
Approved IMA 1984
Physical Properties:
 Cleavage:
[100] Perfect, [010] Perfect
 Color:
brownish yellow or dark brown.
 Density:
4.5
 Hardness:
2.5 - Finger Nail
 Luster:
Adamantine - Greasy
 Streak:
light brown
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