Barnesite

General Information:
 Chemical Formula:
Na2V6O16·3(H2O)
 Composition:
(Molecular Weight = 661.66 gm)
Sodium 6.95 % Na
Vanadium 46.19 % V 
Hydrogen 0.91 % H 
Oxygen 45.94 % O 
 Empirical Formula:
Na2V4+6O16·3(H2O)
 IMA Status:
Approved IMA 1963
Physical Properties:
 Color:
brown red or dark red.
 Density:
3.15
 Luster:
Adamantine
 Streak:
brownish red
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