Cerite

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Cerite
Cerite.jpg
Cerite - Bastnas - Deposit Topotype
General
Category Silicate mineral group
Formula
(repeating unit)
(Ce,La,Ca)9(Mg,Fe+3)(SiO4)6(SiO3OH)(OH)3
Identification
Color Clove-brown with a reddish tinge; pale lavender-brown to colorless in thin fragments
Crystal habit Massive granular
Crystal system Trigonal - ditrigonal pyramidal
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 [1][2]

Cerite is a complex silicate mineral group containing cerium, formula (Ce,La,Ca)9(Mg,Fe+3)(SiO4)6(SiO3OH)(OH)3.[1] The cerium and lanthanum content varies with the Ce rich species (cerite-(Ce)) and the La rich species (cerite-(La)).[3][4] Analysis of a sample from the Mountain Pass carbonatite gave 35.05% Ce2O3 and 30.04% La2O3.[1]

Cerite was first described in 1803 for an occurrence in Bastnäs in Västmanland, Sweden.[2] The lanthanum rich species, cerite-(La) was first described for an occurrence in the Khibina massif, Kola Peninsula, Russia in 2002.[5]

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