What is "tschermigite"

n. a water-soluble mineral, ammonium aluminium sulphate (NH₄)Al(SO₄)₂·12(H₂O) found in fumaroles and similar environments

Tschermigite is a mineral form of ammonium alum, formula N H Al( S O)·12(HO). It is found in burning coal seams, bituminous shale and fumaroles. Because of its extreme water solubility it is unlikely to persist except in the dryest of conditions. Discovered in 1852 at Cermiky, also known as Tschermig in Bohemia. It is colorless and named for where it was discovered.