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Formula: (NH4)2Mg2(SO4)3
Anhydrous sulphate, langbeinite group
Crystal System: Isometric
Specific gravity: 2.52 calculated
Hardness: 2
Colour: Grey, white
Solubility: Soluble in water
Environments
Localities
The type locality is Coal mine No. 43, Kopeysk, Chelyabinsk Oblast, Russia.
In air at room temperature, refremovite is hydrated to
boussingaultite in the course of several days. The mineral shows an endothermic
effect at 430oC to 495oC (maximum 475oC) accompanied by a weight loss of 35.8% associated with
decomposition into MgSO4 and (NH4)2SO4 and breakdown of the latter (the calculated
weight loss from the ideal formula is 35.5%). Efremovite occurs as equant grains, 0.01 to 0.015 mm, in grey to white
aggregates with an uneven fracture, vitreous lustre and no cleavage. Aggregates are opaque except in thin slivers. It occurs in
the burning dumps from two shafts in the coal basin. At one shaft the mineral was deposited from hot gases issuing from a fumarole.
The deposit consists of four layers overlying red burning rock
(1) unconsolidated material on top
(2) asphalt-like crust with crystals of sulphur
and kladnoite
(3) crusts and stalactites of mascagnite
(4) dense cement-like grey masses dominantly of efremovite, hydrated in the upper part to
boussingaultite.
At the other shaft, efremovite occurs in a white, fine-grained crust on an incompletely combusted area of the dump that is
enriched by a carbonaceous mass. The efremovite is interpreted to have formed by the decomposition of carbonate rocks (such
as dolostone) in the dumps by sulphuric acid, ammonia, and the products of
burning coal at temperatures between 180oC and 400oC
(AM 76.299-300).
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