General Information:
Chemical Formula:
(Na,K,Pb,Li)3(Ta,Nb,Al)11(O,OH)30
Environment:
In alluvial concentrates. Probalby derived from the alteration of simpsonite in a lithium pegmatite.
IMA Status:
Approved IMA 1969
Locality:
Mumba, Kivu, Zaire.
Name Origin:
Named for Kalervo Rankama (1913-), Finnish geochemist, University of Helsinki.
Physical Properties:
Cleavage:
None
Color:
white or creamy white.
Density:
5.5
Diaphaniety:
Transparent
Habits:
Massive - Uniformly indistinguishable crystals forming large masses., Fibrous - Crystals made up of fibers., Acicular - Occurs as needle-like crystals.
Hardness:
3-4 - Calcite-Fluorite
Luster:
Adamantine
Streak:
white
More details...