General Information:
Chemical Formula:(K,Na)1-x(Ta,Nb,Al)4(O,OH)11
Environment:Granite pegmatites.
IMA Status:Approved IMA 1982
Locality:Kola Peninsula, Russia.
Name Origin:Named for A. F. Sosedko (1901-1957), Russian mineralogist.
Physical Properties: Cleavage:None
Color:colorless.
Density:6.9
Diaphaniety:Transparent
Hardness:6 - Orthoclase
Luminescence:Non-fluorescent.
Luster:Adamantine
Streak:white
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