Formula: Cu4Fe3+O2(V2O7)(VO4)
Specific gravity: 4.10 calculated
Streak: Dark brown-red
Colour: Iron-black to reddish black


Kainoptrite is a relatively new mineral, approved in 2015.


The type locality is the Yadovitaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik volcano, Kamchatka Krai, Russia. Kainotropite is one of the rarest minerals in the Tolbachik fumaroles. It was discovered in a single specimen collected from the Yadovitaya fumarole. It is thought that it was deposited directly from hot gases as a volcanic sublimate, at temperatures not lower than 300oC.
In the holotype specimen, kainotropite forms well-shaped prismatic crystals up to 0.04 × 0.05 × 0.2 mm in size, which are slightly divergent and combined in clusters up to 0.1 × 0.25 mm. They occur on a langbeinite crust overgrowing basalt scoria. Kainotropite is intimately associated with hematite, tenorite, piypite, and a potassium-sodium-lead chlorosulfate. Other associated minerals are lyonsite, rutile, pseudobrookite, arsenic-bearing sanidine, calciolangbeinite and lammerite (CM 58.2.155-165).

At the Southern fumarole field, Mountain 1004, Tolbachik volcano, Kamchatka Krai, Russia, kainotropite was detected in a specimen collected from the fumarolic deposits. Kainotropite occurs here as prismatic crystals up to 0.2 × 0.2 × 0.5 mm in size, isolated or combined in clusters up to 0.7 mm across. The crystals overgrow volcanic scoria strongly altered by fumarolic gas. Kainotropite is associated here with diopside and hematite; supergene minerals observed in this specimen are volborthite, brochantite, gypsum and opal (CM 58.2.155-165).

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