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Formula: KCa12(SiO4)4(SO4)2O2F
Valence: KCa12(SiO4)4(S6+O4)2O2F
Nesosilicate (insular SiO4 groups), arctite group,
arctite supergroup, forms a series with
dargaite
Crystal System: Trigonal
Specific gravity: 3.119 calculated
Hardness: 5
Streak: White
Colour: Colourless
Luminescence: None
Environments
Nabimusaite is formed from high-temperature syn-pyrometamorphic alteration of
primary
ye’elimite-larnite rocks during
combustion events as a result of the reaction of potassium-enriched, sulphate-bearing melt with
larnite and ellestadite. Associated
minerald include larnite, ye’elimite,
brownmillerite,
fluormayenite-fluorkyuygenite,
gehlenite, ternesite,
jasmundite, periclase,
oldhamite, covellite,
dzierżanowskite, shulamitite,
magnesioferrite and spinel
(HOM).
Localities
At the type locality, Jebel Harmun, Quds Governorate, West Bank, Palestine, nabimusaite has been discovered in
larnite-ye’elimite nodules of
pyrometamorphic rocks of the Hatrurim Complex. Nabimusaite is colourless, transparent with a white streak, has a
vitreous lustre and does not show luminescence. It is brittle, but shows pronounced parting and imperfect cleavage. Two
other new minerals in the Hatrurim Complex with related modular structures are
zadovite and aradite.
The mineral assemblage and paragenesis suggests that nabimusaite formed as a result of the reaction of
potassium-enriched, sulphate-bearing melt with larnite and
ellestadite
(MM 79.5.1061-1072).
Nabimusaite occurs as xenomorphic, poikilitic (the texture of an igneous rock in which small crystals of one
mineral occur within crystals of another) crystals 0.1 to 0.2 mm in size, filled with inclusions of
larnite and ye’elimite. Very rarely
nabimusaite grains reach 0.5 mm in size. Associated minerals include
brownmillerite, covellite,
dzierżanowskite,
fluorellestadite, gehlenite,
larnite, magnesioferrite,
oldhamite, periclase,
shulamitite, spinel and
ye'elimite
(Mindat).
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