Godovikovite

Godovikovite
White godovikovite with minor red demicheleite-(Cl) (IMA 2008-020) from La Fossa Crater, Vulcano Island, Messina Province, Sicily, Italy
General
Category	Sulfates
Formula	(NH4)(Al,Fe+3)(SO4)2
IMA symbol	God [1]
Strunz classification	07.AC.20(07)
Dana classification	28.03.05.02
Crystal system	Trigonal
Crystal class	Trapezohedral
Space group	Trigonal enantiomorph
Unit cell	a = 4.75Å, c = 8.30(1)Å
Identification
Formula mass	244.36
Colour	White, colourless
Crystal habit	Very small hexagonal blades
Fracture	Uneven
Mohs scale hardness	2
Luster	Earthy/dull
Streak	White
Diaphaneity	Transparent to translucent
Density	2.53
Birefringence	0.009
Solubility	Slowly in H2O

Godovikovite is a rare sulfate mineral with the chemical formula: (NH₄)Al(SO₄)₂. Aluminium can partially be substituted by iron. Hydration of godovikovite gives the ammonium alum, tschermigite. The mineral forms cryptocrystalline, often porous, masses, usually of white colour. Single crystals are very small hexagonal blades. Typical environment for godovikovite are burning coal sites (mainly dumps). ^[2] There the mineral acts, together with millosevichite, as one of the main components of so-called sulfate crust. ^{[3] [4]}

It was first described in 1988 for an occurrence in the Chelyabinsk coal basin, Chelyabinsk Oblast, Southern Urals, Russia, and named for Russian mineralogist Aleksandrovich Godovikov (1927–1995). ^[5]

References

1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
2. "Godovikovite" (PDF). Handbook of Mineralogy. Archived from the original (PDF) on 26 June 2022. Retrieved 15 February 2021.
3. Chesnokov B. V. and Shcherbakova E. P. 1991: Mineralogiya gorelykh otvalov Chelyabinskogo ugolnogo basseina - opyt mineralogii tekhnogenesa. Nauka, Moscow
4. Jambor J. L. and Grew E. S. 1990: New mineral names. American Mineralogist, 76, pp. 240-246
5. Godovikovite on Mindat.org

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