Cerium carries the chemical symbol Ce and atomic number 58, placing it within the lanthanide group of rare-earth elements.

The rare-earth label is misleading in cerium’s case. It is actually present in Earth’s crust in quantities comparable to copper and roughly three times greater than lead.

The element was identified in 1803 by Swedish chemists Jöns Jacob Berzelius and Wilhelm Hisinger, with German chemist Martin Heinrich Klaproth arriving at the same discovery independently.

Its name honors Ceres, the celestial body that had been found just two years earlier in 1801. At the time of naming, Ceres was classified as a planet rather than the dwarf planet or asteroid it would later be recognized as.

Through that naming, cerium carries an indirect connection to the Roman goddess Ceres, who presided over grain, fertility, and motherhood.

Pure cerium is a soft, silvery-gray metal that yields easily to a knife blade.

In finely divided form, cerium behaves in a way that sets it apart from most metals. Small filings or shavings can ignite on contact with air, throwing off bright sparks.

That same fiery tendency makes cerium a key ingredient in lighter flints. The component most people think of as a flint is typically not natural flint rock at all but rather mischmetal, an alloy in which cerium makes up roughly half the composition.

Cerium oxide, commonly called ceria, is widely used as a polishing agent for glass. It produces the level of surface clarity required for mirrors, camera lenses, and precision optical instruments.

Many of the polished optics people encounter regularly, from telescope lenses to smartphone camera glass, may owe part of their clarity to cerium compounds used during the finishing process.

In automotive technology, cerium plays a role in catalytic converters, helping to break down harmful exhaust emissions. The element also contributes to petroleum refining, where cerium-based catalysts assist in converting crude oil into usable fuels.

During the Manhattan Project, cerium compounds were examined for use in crucibles designed to handle uranium and plutonium. The demands of wartime nuclear research drove improvements in the techniques used to produce cerium in highly pure form.

Bastnäsite and monazite are the primary ores from which cerium is commercially extracted, and both rank among the most significant rare-earth mineral sources in the world.

The Swedish village of Bastnäs, where cerium was first identified, holds a modest but genuine place in scientific history as the site of discovery for several rare-earth elements.