Wilkinsonite

General Information:
 Chemical Formula:
Na2Fe++4Fe+++2Si6O20
 Composition:
(Molecular Weight = 869.56 gm)
Sodium 5.29 % Na
Iron 38.53 % Fe
Silicon 19.38 % Si
Oxygen 36.80 % O 
 Empirical Formula:
Na2Fe2+4Fe3+2Si6O20
 IMA Status:
Approved IMA
Physical Properties:
 Color:
black.
 Diaphaniety:
Subtransparent to Opaque
 Hardness:
5 - Apatite
 Luster:
Vitreous (Glassy)
 Streak:
brown
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