Common as copper, cerium (No. 58 on the periodic table) is one of the most abundant of the rare earth metals.
It is often converted into cerium oxide, which is known as "optician's rouge" for its ability to polish glass and semiconductors. Cerium oxide (CeO2) is also essential in catalytic converters, helping to turn smog-causing molecules into carbon dioxide, as well in the massive carbon-arc lighting used on movie sets.
Bloomberg reported recently that cerium oxide prices rose to $36 per kilogram Oct. 19 from about $4.70 a kilogram on April 20, according to Metal-Pages.