Formula: Ce4(Ti,Fe2+,Fe3+)5O8(Si2O7)2
Sorosilicate (Si2O7 groups), chevkinite group
Crystal System: Monoclinic
Specific gravity: 4.53 to 4.67 measured, 4.99 calculated
Hardness: 5 to 6
Streak: Grey-brown
Colour: Black, dark brown, dark reddish brown
Solubility: Soluble in hydrochloric and nitric acids, HF and AR, but not in bases
Common impurities: Ca,Nb,Mg,Th,Sr,Zr
Weakly RADIOACTIVE
Environments
Igneous environments
Pegmatites
Carbonatites
Chevkinite-(Ce) occurs as a minor accessory mineral in volcanic ash beds and
rhyolite, but more
commonly as an accessory mineral in alkaline or peralkaline granite,
granite
pegmatites,
nepheline syenite,
syenite and syenite
pegmatites; rarely in
fenite and
carbonatites
(Dana, HOM, Webmin).
Localities
At the type locality, Pit No. 17, Ilmen Mountains, Chelyabinsk Oblast, Russia, chevkinite-(Ce) occurs as
crystals up to 5 cm in aegirine -
quartz - feldspar
pegmatites associated with
titanite, amphiboles,
allanite-(Ce) and aegirine
(Mindat).
In the Aquarius Mountains, Mohave county, Arizona, USA, chevkinite-(Ce) is associated with
titanite,
monazite, apatite,
cronstedtite and quartz
(HOM).
At the Wausau Intrusive Complex, Marathon county, Wisconsin, USA, there have been three finds of
chevkinite-(Ce).
The first, near the contact with a large quartzite xenolith,
occurred in small pegmatoidal veins and
clots largely composed of feldspar,
quartz,
amphiboles, zircon and grains
of an altered
chevkinite-group mineral. Accessory minerals include apatite,
monazite, and allanite-(Ce).
The second find was in a quarry where the syenite was cut by small
pegmatites containing small
crystals of a chevkinite-group mineral associated with quartz,
microcline, albite,
biotite, aegirine,
ilmenite, probable
rhabdophane-(Ce),
xenotime-(Y), amphiboles,
fayalite, a
euxenite-like oxide and
magnetite.
The third find was in heavy mineral separates prepared from a fine-grained
mafic dike cutting
granite. Associated minerals include
amphiboles,
biotite, chlorite,
fluorapatite and very rare
columbite-group and
monazite-group species
(R&M 87.2.172-173).
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