Tectosilicate (framework silicate)
Specific gravity: 2.48
Hardness: 6 to 7
Colour: Pale to medium violet, reddish violet, sometimes barely tinted purple
Solubility: Easily fusible, gelatinises with acids (Dana)
Common impurities: Ca,K,Cl,H2O,S
Plutonic igneous environments
Ussingite occurs in syenite pegmatites and and associated
At Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Quebec, Canada, ussingite occurs in sodalite xenoliths in an intrusive alkalic gabbro - syenite complex, associated with villiaumite, lovozerite, eudialyte, lueshite, griceite and natrophosphate (HOM).
At the type locality, the Kangerluarsuk Fjord, Ilímaussaq complex, Narsaq, Kujalleq, Greenland, ussingite occurs as a secondary mineral in a syenite pegmatite, and in sodalite-bearing xenoliths (Mindat). Associated minerals include microcline, natrolite and aegirine (HOM).
At the Palitra pegmatite, Karnasurt mine, Kedykverpakhk Mountain, Lovozersky District, Murmansk Oblast, Russia, ussingite occurs as masses to 10 cm closely associated with sodalite, steenstrupine-(Ce), lomonosovite, vuonnemite and serandite. Ussingite replaces analcime, and pseudomorphs of ussingite after analcime are common (Minrec 36.5.412).
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