Bannermanite

General Information:
 Chemical Formula:
(Na,K)xV++++xV+++++6-xO15
 IMA Status:
Approved IMA 1981
Physical Properties:
 Cleavage:
[110] Perfect, [010] Good
 Color:
black.
 Density:
3.5
 Luster:
Sub Metallic
 Streak:
brownish black
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