General Information:
Chemical Formula:
(Fe,Mn,Nb)(Nb,W,Ta)O4
IMA Status:
Not IMA Approved
Physical Properties:
Cleavage:
[???] Perfect
Color:
black.
Density:
6.3 - 6.55, Average = 6.42
Diaphaniety:
Opaque
Hardness:
5-6 - Between Apatite and Orthoclase
Luster:
Sub Metallic
Streak:
brownish black
More details...