Images
Formulae:
fluorbritholite-(Ce):
(Ce,Ca)5(SiO4)3F
fluorbritholite-(Nd):
Cd2Nd3(SiO4)3F
fluorbritholite-(Y):
(Y,Ca)5(SiO4)3F
Nesosilicates (insular SiO4 groups), britholite group,
apatite supergroup
Specific gravity: fluorbritholite-(Ce) 4.66; fluorbritholite-(Y) 4.609 calculated
Hardness: fluorbritholite-(Ce) 5; fluorbritholite-(Y) 5½
Streak: fluorbritholite-(Ce) Pale brown; fluorbritholite-(Y) Pale brownish to almost white.
Colour: fluorbritholite-(Ce) Pale yellow, tan, reddish-brown; fluorbritholite-(Y) Light pinkish-brown to brownish-pink;
light brown; dark brown
Environments
Plutonic igneous environments
Pegmatites
Localities
The Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Quebec, Canada is the type locality for
fluorbritholite-(Ce). It occurs in vugs in nepheline syenite,
marble xenoliths, sodalite
syenite xenoliths and pegmatite dykes,
associated with zircon, ussingite,
steenstrupine-(Ce), sodalite,
serandite, microcline,
lueshite, lovozerite,
götzenite, fluorite,
eudialyte, chabazite, carbonate-rich
fluorapatite, calcite,
biotite, ancylite,
analcime, albite and
aegirine
(Mindat).
There are three Co-Type Localities for fluorbritholite-(Y), Kråkmo, Hamarøy, Nordland, Norway, Lagmannsvik, Hamarøy, Nordland, Norway and
Vyuntspakhk Mt, Western Keivy Massif, Keivy Mountains, Lovozersky District, Murmansk Oblast, Russia.
At Lagmannsvik and Kråkmo, Hamarøy, Nordland, Norway, fluorbritholite-(Y) occurs in alkaline
granite related pegmatites
(Mindat).
At Kråkmo, Hamarøy, Nordland, Norway, fluorbritholite-(Y) is associated with
fluorapatite, quartz,
fluorite and allanite-(Ce)
(HOM).
At Lagmannsvik, Hamarøy, Nordland, Norway, fluorbritholite-(Y) occurs in pegmatite cutting alkaline
granite as irregular grains and
crystals up to 1 mm embedded in granular aggregates of of cream coloured yttrium-bearing fluorite
and allanite-(Ce).
Associated minerals include yttrium-bearing fluorite,
allanite-(Ce), quartz,
magnetite, fluorapatite,
aluminocerite-(Ce), bastnäsite-(Ce),
britholite-(Y), gadolinite-(Y),
hundholmenite-(Y),
thalénite-(Y),
kainosite-(Y) and tengerite-(Y)
(HOM, Mindat).
At Vyuntspakhk Mt, Western Keivy Massif, Keivy Mountains, Murmansk Oblast, Russia, fluorbritholite-(Y) occurs in a
microcline variety amazonite-bearing pegmatite vein
(Mindat).
At the Longs Peak - St Vrain batholith near Jamestown, Jamestown District, Boulder county,
Colorado, USA, centimetre to decimetre sized mineralised pods and veins consist of zoned
mineral assemblages dominated by fluorbritholite-(Ce)
in a core 10 cm thick, with monazite-(Ce),
fluorite and minor quartz,
uraninite and sulphides. The core is surrounded by a
typically millimetre thick rim of allanite-(Ce), with
minor monazite-(Ce) in the inner part of the rim.
Bastnäsite-(Ce),
törnebohmite-(Ce) and
cerite-(CeCa) appear in an intermediate zone between core and
rim, often just a few hundreds of microns wide
(R&M 96.3.252-253).
Back to Minerals