Phosphate of ytterbium, xenotime group
Specific gravity: 5.85 calculated
Colour: Colourless to yellow, light brown
Luminescence: No observed fluorescence
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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