White godovikovite with minor red demicheleite-(Cl) (IMA 2008-020). From: La Fossa Crater, Vulcano Island, Messina Province, Sicily, Italy. — Photo: David Hospital · CC BY-SA 4.0
Godovikovite
A rare ammonium-aluminium sulfate that hydrates into the ammonium alum tschermigite.
Intro adapted from Wikipedia (CC BY-SA).
Godovikovite is an IMA-recognized mineral species in the sulfate class, with the chemical formula (NH₄)Al(SO₄)₂.
It crystallizes in the hexagonal crystal system (space group P321). It is a member of the Sabieite structural group.
Key properties: Mohs hardness 2; specific gravity 2.53; Dull to chalky in aggregates luster; optically uniaxial.
IMA symbol God, IMA status: approved, named in 1987.
Occurs as reaction crusts around outlets releasing sulfuric acid from burning coal heaps.
It is found associated with Unspecified anhydrous calcium and magnesium sulfates.
The mineral was named to honor Aleksandr Aleksandrovich Godovikov (1927–1995), Russian mineralogist and Director of the Fersman Mineralogical Museum, Moscow, Russia.