Cerite

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Cerite
Cerite.jpg
Cerite - Bastnas - Deposit Topotype
General
CategorySilicate mineral group
Formula
(repeating unit)
(Ce,La,Ca)9(Mg,Fe+3)(SiO4)6(SiO3OH)(OH)3
Crystal systemTrigonal
Crystal classDitrigonal pyramidal (3m)
(same H-M symbol)
Space groupR3c
Identification
ColorClove-brown with a reddish tinge; pale lavender-brown to colorless in thin fragments
Crystal habitMassive granular
CleavageNone
FractureUneven
Mohs scale hardness5 to 5.5
LusterVitreous to resinous
StreakWhite to greyish white
DiaphaneitySubtranslucent to opaque
Specific gravity4.7 to 4.86
Optical propertiesUniaxial (+)
Refractive indexnω = 1.806 - 1.810 nε = 1.810 - 1.820
Birefringenceδ = 0.010
References[1][2][3]

Cerite is a complex silicate mineral group containing cerium, formula (Ce,La,Ca)9(Mg,Fe+3)(SiO4)6(SiO3OH)(OH)3.[2] The cerium and lanthanum content varies with the Ce rich species (cerite-(Ce)) and the La rich species (cerite-(La)).[4][5] Analysis of a sample from the Mountain Pass carbonatite gave 35.05% Ce2O3 and 30.04% La2O3.[2]

Cerite was first described in 1803 for an occurrence in Bastnäs in Västmanland, Sweden;[3] the lanthanum rich species, cerite-(La) was first described for an occurrence in the Khibina massif, Kola Peninsula, Russia in 2002.[6]

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