Iron oxide, oo sidoo kale loo yaqaano ferric oxide, gubatay limonite, ocher gubtay, cas birta, cas cas, budada cas, Venetian cas (qaybta ugu muhiimsan waa birta oxide), iwm. Qaabka kiimikada Fe2O3, oo ku milma hydrochloric acid, waa casaan. - budo bunni ah.Budada gaduudan-bunniga ah waa midab-fasalka hoose, kaas oo loo yaqaan cas cas ee birta ah.Waxaa loo isticmaalaa rinjiga, khad, caag iyo warshado kale si ay u kiciyaan, wakiilka polishing ee dhalooyinka, dhagaxa dhagaxa iyo biraha, waxaana loo isticmaali karaa sida alaabta ceeriin samaynta birta.