General Information:
Chemical Formula:
(Ce,Th,Ca)5(Si,B)3O12(OH,F)·n(H2O)
Environment:
Alkalic rocks and their cogenetic pegmatites. Also in metamorphosed alkalic rocks.
IMA Status:
Approved IMA 1987
Locality:
Isle of Kjeo in the Langesundfiord district, southern Norway.
Name Origin:
Named froom the Greek meaning "black" and the composition (Cerium).
Physical Properties:
Cleavage:
None
Color:
brown, black, dark brown, or reddish brown.
Density:
4.13
Diaphaniety:
Subtransparent to opaque
Habits:
Tabular - Form dimensions are thin in one direction., Metamict - Mineral originally crystalline, now amorphous due to radiation damage.,
Hardness:
5-6 - Between Apatite and Orthoclase
Luminescence:
Radioactive.
Luster:
Resinous
Streak:
light brown
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