Godovikovite

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]

Godovikovite
White godovikovite with minor red demicheleite-(Cl) (IMA 2008-020) from La Fossa Crater, Vulcano Island, Messina Province, Sicily, Italy
General
CategorySulfates
Formula
(repeating unit)
(NH4)(Al,Fe+3)(SO4)2
IMA symbolGod[1]
Strunz classification07.AC.20(07)
Dana classification28.03.05.02
Crystal systemTrigonal
Crystal classTrapezohedral
Space groupTrigonal enantiomorph
Unit cella = 4.75Å, c = 8.30(1)Å
Identification
Formula mass244.36
ColourWhite, colourless
Crystal habitVery small hexagonal blades
FractureUneven
Mohs scale hardness2
LusterEarthy/dull
StreakWhite
DiaphaneityTransparent to translucent
Density2.53
Birefringence0.009
SolubilitySlowly in H2O

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. 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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