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Formula: Y(VO4)
Valence: Y(V5+O4)
Simple vanadate of yttrium,
xenotime group
Crystal system: Tetragonal
Specific gravity: 4.25 calculated
Hardness: 5
Colour: Pale tan, yellow, canary-yellow, yellow-brown
Environments
Localities
At the type locality, the Evans-Lou Mine, Lake Saint-Pierre, Saint-Pierre-de-Wakefield, Val-des-Monts, Les
Collines-de-l'Outaouais RCM, Outaouais, Québec, Canada, the
pegmatite has giant
perthite-quartz at the centre and
perthite-plagioclase
quartz on the periphery.
Fergusonite and hellandite
were deposited before a period of brecciation and sometimes appear as
fragments surrounded by quartz. Large crystals of pink
microcline (up to 5 X 2 feet) and weathered
allanite (up to 4 X 2 feet) appear on the quarry wall in the giant
perthite-quartz zone. Also noted
in this zone is an abundance of vugs up to several feet across that contain large
quartz crystals (up to 7 lbs) commonly coated with
montmorillonite, goethite
or hematite. Of the accessory minerals on the dump,
biotite, yttrium-bearing
spessartine, allanite,
hematite, goethite and
fergusonite are the most common, probably in that order of abundance.
In the first-found specimen of wakefieldite taken from the dump, a pale tan mixture of
wakefieldite, intimately associated with quartz and
hellandite, and lesser amounts of
kainosite-(Y) and
montmorillonite, filled cavities in
quartz in three sites on the specimen. Subsequently, canary-yellow
wakefieldite was discovered at two locations within the quarry. At one, wakefieldite was associated
with montmorillonite in vuggy
quartz; yttrium-bearing
fluorapatite and
thorogummite were found nearby. At the other location, in the giant
perthite-quartz zone,
wakefieldite was mixed with montmorillonite in cavities in
quartz near a cluster of
fergusonite crystals. Fine-grained
xenotime occurred a few inches away. Wakefieldite was found with
montmorillonite in quartz
in four additional specimens on the dump; in two of these specimens wakefieldite was intimately associated
with hellandite
(AM 56.395-410 as wakefieldite).
Wakefieldite-(Y) from the Evans-Lou Mine -
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