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Formula: Yb(PO4)
Phosphate of ytterbium, xenotime
group
Crystal System: Tetragonal
Specific gravity: 5.85 calculated
Streak: White
Colour: Colourless to yellow, light brown
Luminescence: No observed fluorescence
Environments
Localities
At the type locality, Shatford Lake pegmatite, Lac-du-Bonnet area, Manitoba, Canada, the
pegmatite is a
gadolinite-rich subgroup of an
niobium-yttrium-fluorine
granitic
pegmatite derived from
biotite granite.
Samples with
xenotime-(Yb) were found in a small trench in the centre of the main subvertical dike as granular aggregates
<50 microns across and as separate small (up to 20 microns) grains encased in clots of ferrian
muscovite that also contain albite,
microcline and quartz. The clots
of mica are scattered throughout the saccharoidal
albite unit, and are associated with
columbite-(Fe), albite,
microcline and quartz.
Beryl, microlite,
fluorite and molybdenite were
identified in other units of the parent pegmatite. In
general, the minerals of the pegmatite group also include
biotite, chlorite,
almandine, spessartine,
topaz, zircon,
titanite, epidote,
thorite, gadolinite-(Y),
allanite, apatite,
monazite, xenotime-(Y),
uraninite, cassiterite,
magnetite, pyrite and
niobium-bearing rutile
(CM 37.1303-1306).
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