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Formula: KNa(SO4)
Anhydrous sulphate
Crystal System: Trigonal
Specific gravity: 2.687 calculated
Hardness: 2 to 3
Streak: White
Colour: Pale blue to green
Environments
Belomarinaite is a new mineral, approved in 2018 and to date (April 2023) reported only from the Tolbachik
volcano (several localities)
Localities
At the Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik Volcanic
field, Milkovsky District, Kamchatka Krai, Russia, belomarinaite was found as colourless or white, usually
semitransparent hexagonal tabular or lamellar crystals up to 0.6 mm across and up to 0.05 mm thick. They are
combined in crusts or openwork clusters covering basalt
scoria altered by fumarolic gas and overgrowing crystals of
alluaudite-group arsenates,
namely johillerite,
nickenichite and
calciojohillerite. In most cases, crystals of
belomarinaite are covered by powdery aggregates consisting of tiny (up to 20 microns across) dark red-brown
lamellar crystals of hematite, and blue to lilac
johillerite crystals. Other associated minerals are
sanidine, anhydrite and
calciolangbeinite.
Belomarinaite is a
primary fumarolic mineral. The temperatures measured in
pockets in the Arsenatnaya fumarole from which it was collected varied from 360 to 400oC. Thus, it is
assumed that this mineral formed at temperatures not lower than 400oC, being deposited directly from
the gas phase as a volcanic sublimate
(CM 58.2.167-181).
At the type locality, the Toludskoe lava field, 2012-2013 Fissure Tolbachik Eruption site, Plosky Tolbachik
volcano, Tolbachik volcano, Kamchatka Krai, Russia, the lava field formed during the 2012–2013 Tolbachik Fissure
eruption. Belomarinaite occurs as arborescent aggregates of tabular crystals (1 mm × 0.3 mm × 0.1 mm)
comprising hematite impurities. The average size of the aggregates is
0.5 to 0.7 mm
(MM 83.4.569-575).
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