Willemseite

General Information:
 Chemical Formula:
(Ni,Mg)3Si4O10(OH)2
 Composition:
(Molecular Weight = 456.63 gm)
Magnesium 3.99 % Mg
Silicon 24.60 % Si
Nickel 28.92 % Ni
Hydrogen 0.44 % H 
Oxygen 42.05 % O 
 Empirical Formula:
Ni2.25Mg0.75Si4O10(OH)2
 IMA Status:
Approved IMA 1968
Physical Properties:
 Cleavage:
[001] Perfect
 Color:
light green.
 Density:
3.31
 Hardness:
2 - Gypsum
 Streak:
greenish white
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