Cerium is the most abundant of the rare earth metals and is found in a number of minerals, which include allanite (also know as orthite), monazite, bastnasite, cerite and samarskite. Monazite and bastnasite are presently the two most important sources of cerium. Some of the applications of cerium include: pyrophoric alloys for cigarette lighters; making aluminium alloys and in some steels and irons; in cast iron it opposes graphitisation and produces a malleable iron; in steels it removes sulphides and oxides and completely degasifies; in stainless steel it is used as a precipitation-hardening agent; adds heat resistance to magnesium castings in magnesium alloys; and it is used in used in the manufacture of glass, as a component and a decolouriser.