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Formula: CaCe(Al2Fe2+)[Si2O7][SiO4]O(OH)
Sorosilicate (Si2O7 groups), allanite group of
the epidote supergroup,
cerium-bearing mineral
Specific gravity: 3.4 to 4.2
Hardness: 5 to 6½
Streak: Light brown
Colour: Light brown to black
Solubility: Gelatinises with hydrochloric acid (Dana)
Environments
Plutonic igneous environments
Pegmatites
Metamorphic environments
Allanite-(Ce) is an accessory mineral in some granites and
granite pegmatites
and syenites, and more rarely in
gabbroic pegmatites;
it occurs rarely in schist,
gneiss and some contact metamorphosed
limestones, and it can be a detrital mineral (Dana, HOM).
Associated minerals
include epidote, muscovite and
fluorite (HOM, Mindat).
Localities
At lots 10 and 11 of concession 1, Bathurst Township, Lanark County, Ontario, Canada (DeWitts corner), the deposit is
located in the Grenville Geological Province, which consists mostly of
marble, gneiss, and
quartzite.
Syenite-migmatite was
also reported in the area where the vein-dikes are located. Characteristic features of the vein-dikes include the
fact that perfectly formed euhedral crystals of different minerals can often be found floating in
calcite with no points of contact with the walls. Sometimes these crystals
have inclusions of calcite, irregular or rounded in shape. It has been argued
that at least some of the vein-dikes were formed as a result of melting of Grenville
marble.
Allanite-(Ce) is a rare mineral at DeWitts Corners that occurs as brown semitransparent patches to 4 mm on
dark green to nearly black diopside crystals
(R&M 97.6.556-564).
The type locality is Qáqarssuatsiaq, Aluk Island, Kujalleq, Greenland, Denmark.
At the Trimouns quarry, Ariège, France, allanite-(Ce) is found in dolomite and
talc, and may be associated with bastnäsite,
synchysite, parisite,
quartz, calcite, and very rarely
hingganite (R&M 35.3.232, R&M 86.5.451).
At the Bastnas mines, Vastmanland, Sweden, allanite-(Ce) occurs within amphibole
skarn and as compact masses with
cerite-(CeCa).
Associated minerals include chalcopyrite,
bismuthinite, bastnäsite and rarely
linnaeite (R&M 35.3.193-194).
At Pacoima Canyon, Los Angeles County, California, USA, allanite occurs with
zircon and
apatite in a pegmatite
(AM 56.447).
At the Tiro Estrella mine, Lincoln County, New Mexico, USA, allanite-(Ce) occurs in
quartz
veins with feldspar.
At the Dafoe Property, Pierrepont, St Lawrence county, New York, USA, allanite-(Ce) occurs as dark brown-to-black,
acicular crystals that occur in sprays to 0.5 cm. They are best preserved as inclusions in transparent
quartz and calcite. These can usually be
seen on the walls of molds of quartz after
tourmaline or unidentified species (likely
baryte or anhydrite).
Allanite-(Ce) more commonly occurs as mats and fillings between, and sometimes on,
calcite and quartz. Not all these
crystals contain enough cerium to be classified as allanite-(Ce), but
rather some are cerium-rich epidote
R&M 97.3.247).
At Power's Farm, Pierrepont, St. Lawrence county, New York, USA, allanite-(Ce) occurs as a late-stage mineral
associated with
microcline, quartz, and
chamosite (R&M 85.2.162).
At the danburite occurrence near Russell, St. Lawrence county, New York, USA,
allanite-(Ce) forms crystals on tremolite (R&M 90.3.217).
At the Selleck Road Locality, West Pierrepont, St. Lawrence county, New York, USA, allanite-(Ce), or a closely
related species, occurs
on the surfaces of microcline crystals (R&M 91.2.121).
In New York city, New York, USA, an allanite-(Ce) crystal has been found at the southeast corner of 56th and
Broadway embedded in
albite pegmatite, and
another allanite-(Ce) crystal has been found embedded in
quartz from the Brooklyn-Battery Tunnel (R&M 84.3.221-222).
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