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Formula: K(Al,Zn)2(As,Si)2O8
Feldspar group
Crystal System: Monoclinic
Specific gravity: 2.92 calculated
Hardness: 5 to 6
Colour: Colourless
Luminescence: No fluorescence under UV
Environments
Filatovite is a rare mineral; it was approved in 2004, but to date (January 2023) it has been reported only from
the type locality.
Localities
At thr type locality, the Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik Volcanic field,
Milkovsky District, Kamchatka Krai, Russia, filatovite was found in fumaroles. The Great Fissure Tolbachik
Eruption is the largest basaltic eruption in modern history. It was active in 1975-76 and consisted of two Breaches
(North and South) and seven cones. Beginning in the late 1970s, fumarolic activity of the Great Fissure Tolbachik
Eruption resulted in the crystallisation of a unique mineral assemblage, with twenty-four new mineral species
discovered to date. Crystals of filatovite were found in products of fumarolic activity where the temperature of
gases in the fumarole was about 410 to 420°C.
Filatovite is associated with alumoklyuchevskite,
lammerite, johillerite,
sylvite, arsenic-bearing
orthoclase, hematite and
tenorite. The filatovite occurs as prismatic crystals up to 0.3 mm and
intergrowths of crystals, in close association with elongated crystals of
arsenic-bearing orthoclase
(EJM 16.3.533-536).
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