What is "letovicite"

n. (context mineralogy English) (NH₃)₃H(SO₄)₂ A triclinic mineral containing hydrogen, hydrogen, nitrogen, oxygen, and sulfur.

Letovicite is an ammonium sulfate mineral with composition (NH)H(SO) (IUPAC: triammonium sulfate hydrogensulfate, Nickel–Strunz classification 07.AD.20).

It is a rare colorless or white monoclinic secondary mineral formed during the burning of waste coal heaps and as a deposit in hot springs. It was first described from the Letovice region of Moravia in 1932.