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Formula: Ba(Al2Si2O8)
Tectosilicate (framework silicate), feldspar group, high-temperature
paramorph of celsian and
paracelsian, barium-bearing
mineral
Crystal System: Hexagonal
Specific gravity: 3.305 calculated
Streak: White
Colour: Colourless
Environments
Hexacelsian is a comparatively new mineral, approved in 2015 and to date (October 2023) reported only from
the Hatrurim basin (two localities).
Localities
At the type locality, the Gurim anticline, Hatrurim Basin, Tamar Regional Council, Southern District, Israel, two
new barium-bearing minerals,
gurimite and hexacelsian, were discovered in veins of
paralava cutting
gehlenite-flamite
hornfels. Gurimite and
hexacelsian occur in oval polymineralic inclusions in paralava
and are associated with gehlenite,
pseudowollastonite or
wollastonite, rankinite,
flamite, larnite,
schorlomite, andradite,
fluorapatite,
fluorellestadite,
kalsilite, cuspidine,
aradite, zadovite and
khesinite. Gurimite and
hexacelsian form elongate crystals less than 10 µm thick. The minerals are colourless and transparent with a
white streak and vitreous lustre
It is suggested that after relatively fast crystallisation of the main constituents of the
paralava, gurimite,
hexacelsian and other barium-bearing phases crystallised from
residual melt enriched in incompatible elements that
filled interstices between crystals of the main constituents
(MM 81.4.1009-1019).
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