Cerium is a rare earth element denoted by the atomic symbol Ce. The most abundant of this type of element, cerium has an atomic number of 58, and an atomic weight of 140.12. It is an iron-gray metal with a melting point of 1,463°F (795°C) and a boiling point of 5,895°F (3,257°C). Cerium is a highly reactive element that will decompose in cold water slowly but hot water rapidly. In fact, it may catch fire if cut with a knife or ignite spontaneously if finely divided.

The first allusion to cerium appears in 1751, when Axel Crönstedt (1722-1765) described a new mineral found in the Bastnäs Mineat Riddarhyttan, Sweden. At first, chemists thought the mineral might be a form of tungsten since it was so heavy.

A correct description of the mineral appeared from two sources at almost the same time. One source...