Kogarkoite
(repeating unit)Na3(SO4)F IMA symbol Kog[1] Strunz classification 7.BD.15 Crystal system Monoclinic Crystal class Pyramidal (2/m)
(same H-M symbol) Space group P21/m Unit cell a = 18.07, b = 6.94
c = 11.44 [Å]; β = 107.72°; Z = 12 Identification Color Colorless, pale sky-blue, pale pink, lilac Crystal habit Tabular crystals, granular, earthy aggregates, pseudorhombohedral Twinning Common Mohs scale hardness 3.5 Luster Vitreous to dull Streak White Diaphaneity Transparent to translucent Specific gravity 2.66 Optical properties Biaxial (+) Refractive index nα = 1.439 nβ = 1.439 nγ = 1.442 Birefringence δ = 0.003 2V angle Small, approaching zero Ultraviolet fluorescence Cream to pale blue under SW UV and green under LW UV Solubility Slowly soluble in water References [2][3][4]
(same H-M symbol)
c = 11.44 [Å]; β = 107.72°; Z = 12
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
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
References
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