Kogarkoite

kogarkoite

villiaumite

lorenzenite

lamprophyllite

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Formula: Na3(SO4)F
Anhydrous
Crystal System: Monoclinic
Specific gravity: 2.66 measured, 2.676 calculated
Hardness: 3½
Streak: White
Colour: White, pale blue, pale pink
Luminescence: Fluoresces cream to pale blue under short wave UV and green under long wave
Solubility: Slowly soluble in water
Melting point: 781oC
Environments

Plutonic igneous environments
Pegmatites
Hot springs

Localities

At the Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Quebec, Canada, kogarkoite occurs in sodalitesyenite xenoliths associated with an intrusive alkalic gabbrosyenite complex (HOM).

At the type locality, the Alluaiv Mountain, Lovozersky District, Murmansk Oblast, Russia, the occurrence is in a nepheline syenite pegmatite, closely associated and at places intergrown with villiaumite. Other associated minerals include nepheline, feldspar, aegirine, lorenzenite, apatite and lamprophyllite. The pale blue kogarkoite occurs as grains and aggregates occupying interstices between nepheline and feldspar. The situation for formation of these minerals seems to be late-stage crystallisation at a temperature near the critical temperature for water, where these compounds are virtually insoluble (AM 58.116-127).
Other associated minerals include thermonatrite, sidorenkite, aegirine and lorenzenite (HOM).

At the Hortense Hot Spring, Chalk Creek District, Chaffee county, Colorado, USA, kogarkoite occurs in a repeatedly generated, white, soft sublimate around steaming vents of hot-spring water, at temperatures up to 84oC. Opal, mostly milky, is the principal constitutent of the incrustations, and the only crystalline phase that can be readily recognised is kogarkoite. This occurs in small clusters or single crystals up to 0.7 mm in size but mostly in the range 0.1 to 0.3 mm (AM 58.116-127).
Other associated minerals, very fine grained, include burkeite, trona, halite, fluorite, calcite and phillipsite (HOM)

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