Kogarkoite

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Kogarkoite
Kogarkoite - Poudrette quarry, Mont Saint-Hilaire, Quebec, Canada.jpg
General
CategorySulfate mineral
Formula
(repeating unit)
Na3(SO4)F
IMA symbolKog[1]
Strunz classification7.BD.15
Crystal systemMonoclinic
Crystal classPyramidal (2/m)
(same H-M symbol)
Space groupP21/m
Unit cella = 18.07, b = 6.94
c = 11.44 [Å]; β = 107.72°; Z = 12
Identification
ColorColorless, pale sky-blue, pale pink, lilac
Crystal habitTabular crystals, granular, earthy aggregates, pseudorhombohedral
TwinningCommon
Mohs scale hardness3.5
LusterVitreous to dull
StreakWhite
DiaphaneityTransparent to translucent
Specific gravity2.66
Optical propertiesBiaxial (+)
Refractive indexnα = 1.439 nβ = 1.439 nγ = 1.442
Birefringenceδ = 0.003
2V angleSmall, approaching zero
Ultraviolet fluorescenceCream to pale blue under SW UV and green under LW UV
SolubilitySlowly soluble in water
References[2][3][4]

Kogarkoite is a sodium sulfate fluoride mineral with formula Na3(SO4)F. It has a pale blue color, a specific gravity of about 2.67 and a hardness of 3.5. The crystal is monoclinic and is a type of naturally occurring antiperovskite. Kogarkoite is named after the Russian petrologist Lia Nikolaevna Kogarko (born 1936) who discovered the mineral.

Discovery and occurrence[edit]

Kogarkoite was first described in 1973 for an occurrence on Alluaiv Mountain, Lovozero Massif, Kola Peninsula, Russia.[3] On Alluaiv it occurs in pegmatitic veins in nepheline syenite. It occurs with sodalite in syenite xenoliths in an alkali intrusive complex at Mont Saint-Hilaire, Canada. In Hortense Hot Spring, Chaffee County, Colorado, it occurs as a sublimate.[2] It occurs at Lake Natron near Ol Doinyo Lengai, Tanzania and Suswa Volcano, Lake Magadi, Kenya.[2][3]

See also[edit]

References[edit]

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b c Handbook of Mineralogy
  3. ^ a b c Mindat.org
  4. ^ Webmineral data