General Information:
Chemical Formula:
(Ca,Ce,La,Na)10-12(Fe++,Mn)(Si,Be)20(O,OH,F)48
Environment:
Occurs in border zone of the only epididymite-eudidymite bearing albitite, in cavities and fractures.
IMA Status:
Approved IMA 1972
Locality:
Ilimaussaq complex, South Greenland.
Name Origin:
Named for Yevgeny Ivanovich Semenov, (1951-), Russian mineralogist, IMGRE, Moscow, Russia.
Physical Properties:
Cleavage:
None
Color:
brown, orange brown, gray, reddish brown, or colorless.
Density:
3.14
Diaphaniety:
Transparent to translucent
Habits:
Pseudo Tetragonal - Crystals show a tetragonal shape., Twinning Common - Crystals are usually twinned.,
Hardness:
3.5-4 - Copper Penny-Flourite
Luster:
Vitreous (Glassy)
Streak:
white
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