Fluorchegemite
Fluorchegemite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₇(SiO₄)₃F₂.
It is a member of the Humite structural group.
Key properties: Mohs hardness 5.5–6; specific gravity 2.91; White streak; optically biaxial.
IMA symbol Fcgm, IMA status: approved, named in 2011.
Formed in the edgrewite-bearing zone of endoskarn (sanidinite facies) at the edge of an altered calciferous xenolith within ignimbrite.
It is found associated with Larnite, edgrewite, wadalite, eltyubyuite, rondorfite, lakargiite, Th-kerimasite, bultfonteinite, killalaite, hillebrandite, afwillite, trabzonite.
Indicates the fluorine-dominant analog of chegemite.
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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