Belomarinaite

belomarinaite

johillerite

nickenichite

calciojohillerite

Images

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

Fumeroles

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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