Alunite

Origin

From its earlier name aluminilite, named in 1824.

Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason, and Abraham Rosenzweig: Dana's new mineralogy, John Wiley & Sons, 1997

Noun

1. (mineral) A gray, water-soluble mineral, potassium aluminium sulphate; the natural source of alum, KAl