Donnayite-(Y)

donnayite-(Y)

ewaldite

mckelvyite-(Y)

arfvedsonite

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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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