"Blue copperas" wani tsohon zamani ne wanda ke nufin wani sinadari da aka sani da jan ƙarfe (II) sulfate pentahydrate. Yana da kauri shuɗin lu'u-lu'u wanda galibi ana amfani dashi a masana'antu da aikace-aikacen noma daban-daban, kamar maganin kashe kwari, fungicides, da taki. Har ila yau, a wasu lokuta ana amfani da ita azaman reagen dakin gwaje-gwaje da kuma samar da rini, pigments, da sauran sinadarai. Kalmar "Copperas" wani tsohon suna ne na ferrous sulfate, wanda wani fili ne na daban wanda kuma ake amfani dashi a fannonin masana'antu da noma iri-iri.