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Formula: NaSr3CaY(CO3)6.3H2O
Hydrated normal carbonate, mckelveyite group,
yttrium-bearing mineral
Crystal System: Triclinic
Specific gravity: 3.30 measured, 3.266 calculated
Hardness: 3
Streak: White
Colour: Pale yellow to yellow, colourless, white, grey, brown to reddish brown
Solubility: Dissolves in hydrochloric acid with strong effervescence
Environments:
Plutonic igneous environments
Pegmatites
Localities
At the type locality, the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Quebec, Canada,
donnayite-(Y) occurs in small quantities in the pegmatite
dykes, miarolitic cavities and interstices in the
nepheline syenite. It is usually associated with
microcline, analcime,
natrolite, calcite,
chlorite, aegirine,
arfvedsonite and minor amounts of
siderite, rhodochrosite,
ancylite, pyrite,
sphalerite, hematite,
goethite, pyrophanite,
catapleiite, gaidonnayite
and astrophyllite. Crystals are usually very small, less than 2 mm in
size. Donnayite-(Y) commonly forms syntactic intergrowths with ewaldite,
mckelveyite-(Y), and rarely
synchysite
(CM 16.335-340).
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