
Argentopyrite

Argentopyrite is a moderately rare sulfide mineral with formula AgFe2S3. It is one of the natural compounds of the "M "Fe2S3 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, AgFeS2, and argentopentlandite, Ag(Fe,Ni)8S8.
Crystal structure.
Although previously assumed orthorhombic, argentopyrite was later shown to be monoclinic, with structural relationship to cubanite. The most important feature of the argentopyrite structure are: