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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 sodalite–syenite
xenoliths associated with an intrusive alkalic
gabbro–syenite 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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