A mineral which is a sulphide of silver and arsenic and usually occurs as masses of prismatic, scarlet crystals.
Formula: Ag₃AsS₃. Crystal system: trigonal.
Mid 19th century; earliest use found in Charles Shepard (1804–1886). Fromthe name of Joseph Louis Proust, French chemist, who first identified the mineral + -ite, after French proustite (F. S. BeudantTraité élém. de min (ed. 2) II. 445).