Fluornatrocoulsellite
Fluornatrocoulsellite is an IMA-recognized mineral species in the halide class, with the chemical formula (Na₁.₅Ca₀.₅)(Mg₁.₅Al₀.₅)F₆F.
It crystallizes in the hexagonal crystal system (space group R-3m). It is a member of the Pyrochlore structural group.
Key properties: Mohs hardness 4.5; specific gravity 2.99; White streak; Vitreous luster.
IMA symbol Fnc, IMA status: approved, named in 2009.
Found in replacement lenses developed during greisenization.
It is found associated with Morinite, gearksutite, vivianite, siderite, K-rich feldspar (adularia), fluorite, quartz.
Prefixes indicate the dominant cation in the X site, fluor, and B site, natro, the base name honors Ruth Elise Coulsell (1912-2000).
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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