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Formula: (NH4)(As2O3)2Br
Halide, arsenic-bearing mineral
Crystal System: Hexagonal
Specific gravity:
Hardness: 1 to 1½
Streak: White with a yellowish tint
Colour: Yellow
Solubility: Insoluble in water, hydrochloric acid, nitric acid and organic solvents
Environments
Ermakovite is a new mineral, approved in 2020 and to date (March 2023) reported only from the type locality.
Localities
The type locality is at Ravat Kishlak, Ayni District, Sughd, Tajikistan. Ermakovite is a fumarolic mineral formed
directly from gas from a natural underground coal fire. Associated minerals are
sulphur, realgar, amorphous
arsenic sulphides, salammoniac,
alacránite, bonazziite and
thermessaite-(NH4). In addition, there are amorphous
As2S3 intergrowths associated with ermakovite. The mineral typically occurs as tabular or
prismatic hexagonal crystals up to 200 μm in size; spherulites and multi-twinned intergrowths are very common.
In terrestrial rocks, bromine minerals are extremely rare with only nine minerals known where bromine is a dominant
component
(MM 87.1.69-78).
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