Johnwalkite

General Information:
 Chemical Formula:
K(Mn++,Fe+++,Fe++)2(Nb,Ta)(PO4)2O2((H2O),OH)2
 IMA Status:
Approved IMA
Physical Properties:
 Cleavage:
[001] Good, [100] Good
 Color:
dark reddish brown or reddish brown.
 Density:
3.4
 Diaphaniety:
Transparent to Translucent
 Hardness:
4 - Fluorite
 Luster:
Vitreous (Glassy)
 Streak:
greenish yellow
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