Metallic cerium is prepared by reduction techniques, such as by reducing cerous fluoride with calcium, or by electrolysis of molten cerous chloride or other cerous halides. Cerium is an iron-grey lustrous metal. It is malleable, and oxidises very readily at room temperature, especially in moist air. Except for europium, cerium is the most reactive of the rare-earth metals. It slowly decomposes in cold water, and rapidly in hot water. Alkali solutions and dilute and concentrated acids attack the metal rapidly. The pure metal may ignite when scratched with a knife.
It is the most abundant of the rare earth metals and is found in minerals including allanite, monazite, cerite, and bastnaesite. There are large deposits found in India, Brazil and the USA.