General Information:
Chemical Formula:
(Mn++,Fe++)(Ta,Nb)2O6
Physical Properties:
Cleavage:
None
Color:
dark brown or black brown.
Density:
7.72
Diaphaniety:
Translucent to Opaque
Hardness:
6 - Orthoclase
Luster:
Sub Metallic
Streak:
dark brown
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