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Formula: (Ce,Ca)5(SiO4)3(OH)
Nesosilicate (insular SiO4 groups), britholite group,
apatite supergroup
Crystal System: Hexagonal
Specific gravity: 4.20 to 4.69 measured, 4.65 calculated
Hardness: 5½
Colour: Colourless, pale pink to pink, pale blue, brown, greenish brown, yellow, resin-brown, black
Strongly RADIOACTIVE
Environments
Plutonic igneous environments
Pegmatites
Metamorphic environments
Britholite-(Ce) is typically thorium-bearing and often metamict.
(Mindat).
It occurs in nepheline syenites and
pegmatites, and in contact deposits related to them.
Associated minerals include zircon,
pyrochlore, titanite,
fluorite, diopside,
andradite, allanite and
vesuvianite
(HOM).
Localities
At the Papanduva pluton, Morro Redondo complex, Tijucas do Sul, Paraná, Brazil, minerals that have been reported
include chevkinite,
allanite,
aenigmatite,
astrophyllite,
narsarsukite,
nacareniobsite-(Ce), britholite-(Ce),
turkestanite, neptunite,
elpidite and bastnäsite
(CM 51.313-332).
At the type locality, Naujakasik, Tunulliarfik Fjord, Ilímaussaq complex, Kujalleq, Greenland,
britholite-(Ce) occurs as brown, apparently hexagonal, prisms embedded in a
nepheline syenite
pegmatite matrix. Associated minerals include
steenstrupine-(Ce),
sodalite, nepheline,
feldspar,
eudialyte, arfvedsonite and
aegirine
(Mindat).
At the San Vito Quarry, San Vito, Ercolano, Mount Somma, Somma-Vesuvius Complex, Naples, Campania, Italy,
britholite-(Ce) occurs as 0.2 mm transparent pale blue hexagonal tabular crystals in volcanic ejecta, mainly
composed of sanidine
(EJM 1.723-725).
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