What is "argentopyrite"

n. (context mineral English) An orthorhombic-dipyramidal mineral containing iron, silver, and sulfur.

Argentopyrite is a moderately rare sulfide mineral with formula AgFeS. It is one of the natural compounds of the ''M ''FeS type, with M being caesium in very rare pautovite, copper in relatively common cubanite, potassium in rare rasvumite and thallium in rare picotpaulite. The type locality is Jáchymov in Czech Republic. Chemically similar mineral include sternbergite (dimorphous with argentopyrite), lenaite, AgFeS, and argentopentlandite, Ag(Fe,Ni)S.