Cerite | |
---|---|
General | |
Category | Silicate mineral group |
Formula (repeating unit) | (Ce,La,Ca) 9(Mg,Fe3+ )(SiO 4) 6(SiO 3OH)(OH) 3 |
IMA symbol | Crt[1] |
Crystal system | Trigonal |
Crystal class | Ditrigonal pyramidal (3m) (same H-M symbol) |
Space group | R3c |
Identification | |
Color | Clove-brown with a reddish tinge; pale lavender-brown to colorless in thin fragments |
Crystal habit | Massive granular |
Cleavage | None |
Fracture | Uneven |
Mohs scale hardness | 5 to 5.5 |
Luster | Vitreous to resinous |
Streak | White to greyish white |
Diaphaneity | Subtranslucent to opaque |
Specific gravity | 4.7 to 4.86 |
Optical properties | Uniaxial (+) |
Refractive index | nω = 1.806 – 1.810 nε = 1.810 – 1.820 |
Birefringence | δ = 0.010 |
References | [2][3][4] |
Cerite is a complex silicate mineral group containing cerium, formula (Ce,La,Ca)
9(Mg,Fe3+
)(SiO
4)
6(SiO
3OH)(OH)
3.[3] The cerium and lanthanum content varies with the Ce rich species (cerite-(Ce)) and the La rich species (cerite-(La)).[5][6] Analysis of a sample from the Mountain Pass carbonatite gave 35.05% Ce
2O
3 and 30.04% La
2O
3.[3]
Cerite was first described in 1803 for an occurrence in Bastnäs in Västmanland, Sweden.[4] The lanthanum rich species, cerite-(La) was first described for an occurrence in the Khibina massif, Kola Peninsula, Russia in 2002.[7]