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Formula: K5Na5Y12Si28O70(OH)2(CO3)8.8H2O
Inosilicate (chain silicate) with double chains, yttrium-bearing mineral
Crystal System: Tetragonal
Specific gravity: 2.61 measured, 2.60 calculated
Hardness: 5
Streak: White
Colour: Pale violet, pink, white
Luminescence: No fluorescence under UV
Environments
Plutonic igneous environments
Pegmatites
Localities
At the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Quebec, Canada,
ashcroftine-(Y) occurs in breccia
zones and miarolitic cavities in nepheline syenite, often
intergrown with lorenzenite
(Dana).
Associated minerals include aegirine,
bastnäsite, lorenzenite,
brookite, elpidite,
leucosphenite, cordylite
and narsarsukite
(HOM).
At the type locality, the Narssârssuk pegmatite, Narsaarsuk Plateau, Igaliku, Kujalleq, Greenland,
ashcroftine-(Y) was found in vugs in aegirine
pegmatite in augite
syenite
(Dana).
Associated minerals include calcite,
elpidite, albite,
quartz, aegirine,
orthoclase, zinnwaldite and
graphite
(HOM).
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