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Formula: (NH4)Al(SO4)2
Anhydrous sulphate
Crystal System: Trigonal
Specific gravity: 2.53 measured, 2.52 calculated
Hardness: 2
Streak: White
Colour: White, colourless in thin section
Solubility: Slowly soluble in water
Environments
Godovikovite occurs as reaction crusts around outlets releasing sulphuric acid from burning coal heaps; it is
associated with unspecified anhydrous calcium and magnesium sulphates
(HOM).
Godovikovite hydrates to tschermigite at room temperature, and
it may occur in burning coal dumps as a dehydration product of
tschermigite
(Mindat).
Localities
At the type locality, Kopeysk, Chelyabinsk Oblast, Russia, godovikovite forms white, compact or porous chalky
aggregates of fine hairs, 0.001 to 0.015 mm in size, in the burning dumps of coal mines. It is one of the main
constituents of the sulphate crusts formed by reaction of sulphuric acid with the material in the dumps. Together
with (Al,Fe)2(SO4)3, it occurs in the lower, hotter zones, which are up to 5 cm
thick and up to 1 m2 in area
(AM 75.241-242).
Spontaneous fires occur on many coal dumps and are known to rage for years or decades, forming many rare
high-temperature minerals
(Mindat).
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