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Formula: NaY(HCO3)(OH)3.4H2O
Hydrated carbonate, yttrium-bearing mineral
Crystal system: Monoclinic
Specific gravity: 2.30 measured, 2.34 calculated
Hardness: 2 to 3
Streak: White
Colour: Honey-yellow to white
Luminescence: Not fluorescent under long wave or short wave UV
Solubility: Dissolves readily with strong effervesce in 10% hydrochloric acid
Environments
Pegmatites
Hydrothermal environments
Localities
At the type locality, the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec,
Canada, thomasclarkite-(Y)occurs as a lale-stage hydrothermal phase in a system of alkaline
pegmatite dikes in
nepheline syenite. Associated minerals include
aegirine, albite,
analcime, ancylite-(Ce),
astrophyllite, calcite,
catapleiite, dawsonite,
elpidite, epididymite,
franconite, gaidonnayite,
galena, genthelvite,
microcline, molybdenite,
natrolite,
petersenite-(Ce),
polylithionite,
pyrochlore, rhodochrosite,
rutile, serandite,
siderite, sphalerite and
zircon.
Thomasclarkite-(Y) occurs as individual crystals and as groups of well-formed, blocky, pseudotetragonal
crystals up to 2 mm in length
(CM 36.5.1293-1300).
Thomasclarkite-(Y) from the Poudrette Quarry -
Image
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