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Formula: Ca12Al14O32[☐4F2]
Multiple oxide
Crystal System: Isometric
Hardness: 5½ to 6
Streak: White
Colour: Colourless, in places with greenish or yellowish tint
Luminescence: Not fluorescent
Environments
Localities
At the type locality, Jebel Harmun, Quds Governorate, West Bank, Palestine, fluormayenite and
fluorkyuygenite are major constituents of
larnite pyrometamorphic rocks. Mineral associations of holotype
fluormayenite and fluorkyuygenite are similar and include
larnite, shulamitite,
chromium-bearing
spinel–magnesioferrite series
minerals, ye’elimite,
fluorapatite–fluorellestadite,
periclase, brownmillerite and
oldhamite, as well as the retrograde phases
portlandite, hematite,
hillebrandite, afwillite,
foshagite, ettringite,
katoite and hydrocalumite.
Fluormayenite and fluorkyuygenite form crystals, usually less
than 20 μm in size. Fluorkyuygenite crystallized initially as
fluormayenite, which later was altered under the influence of water vapour-enriched gases during a combustion
process
(EJM 27.123-136).
Other associated minerals include dzierżanowskite
(MM 81.5.1073–1085) and harmunite (AM 99.965–975).
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