Cerium was discovered in 1803. It is the most abundant of the rare-earth elements. It occurs naturally in monazite sands. It is the key ingredient of Misch-metal alloy. Alloys containing cerium are used to make heat-resistant jet-engine parts. Oxides of cerium are also promising candidates for new petroleum-cracking catalysts.

BCIT Chemistry Resource Center
http://nobel.scas.bcit.ca/resource/