Cerium · element 58
The most common rare earth, named after a dwarf planet, polishing your phone screen and sparking your lighter
Key facts
Cerium is the rare earth that is not rare. It is about as plentiful in the Earth's crust as copper and far more common than tin or lead. It was also the first of the lanthanides to be found, in 1803, and it was named after Ceres, a small world discovered between Mars and Jupiter just two years earlier.
What sets cerium apart chemically is that it can lose four electrons rather than the usual three. That extra flexibility lets its oxide grab and release oxygen on demand, which makes it a superb polish, a useful catalyst and a self-cleaning agent in ovens.
Where it is found
Cerium is the dominant component of the light rare earth ores. Bastnäsite typically contains around half cerium among its rare earth content, and monazite also holds a large share. Both minerals occur in carbonatite intrusions and in placer sands. Cerium also turns up in the mineral cerite, from the Swedish locality where it was first identified.
Production follows the wider rare earth industry. China's Bayan Obo deposit and southern ion-adsorption clays supply most of the world's cerium, with contributions from the United States, Australia, Myanmar and elsewhere. Because cerium is produced in large amounts alongside the more valuable neodymium and praseodymium, it is often the cheapest rare earth, and producers actively look for new ways to use it.
How it was discovered
Cerium was discovered twice in the same year. In 1803 Jöns Jacob Berzelius and Wilhelm Hisinger in Sweden examined a heavy mineral from the Bastnäs mine and identified a new oxide. Independently, Martin Heinrich Klaproth in Berlin reached the same conclusion with the same mineral. Berzelius and Hisinger named it after Ceres, the asteroid, now classified as a dwarf planet, which Giuseppe Piazzi had spotted in 1801.
What they had found was not pure. Cerium oxide from Bastnäs concealed lanthanum, and later didymium, praseodymium and neodymium. Cerium metal itself was first prepared by Mosander in 1825, and pure samples came only with electrolysis in the twentieth century.
What we use it for
Cerium oxide is the standard polish for glass. Its particles are just hard enough to smooth glass and just reactive enough to help remove material chemically as well as mechanically, leaving an optically flat surface. Lenses, mirrors, phone screens and the glass in display panels are finished with it.
In catalytic converters, cerium oxide sits alongside the platinum group metals and acts as an oxygen store, soaking up oxygen when the exhaust is lean and releasing it when the exhaust is rich, which keeps the reactions running smoothly. The same property is used in diesel fuel additives and self-cleaning oven coatings. Cerium is the main component of mischmetal, the alloy that sparks in lighter flints when scraped. Cerium compounds decolourise glass by oxidising green iron impurities, block ultraviolet light in sunglasses and windows, and colour ceramics red.
Reading the numbers
Cerium melts at about 795 °C and boils at about 3443 °C. Its melting point is lower than iron's but its boiling point is far higher, giving an enormous range as a liquid. The density of 6.77 grams per cubic centimetre is a little below iron and just under seven times that of water.
Its configuration is written [Xe] 4f1 5d1 6s2. The single 4f electron marks the true start of the f block. Cerium normally loses three electrons to form Ce3+, like its neighbours, but it can also lose that 4f electron to reach Ce4+ with the stable xenon core, which no other lanthanide does so readily. This dual personality is the source of its catalytic usefulness. Its electronegativity of 1.12 and first ionisation energy of 534 kilojoules per mole are typical of a reactive, electropositive metal.
Safety and the environment
Cerium metal is pyrophoric when finely divided: scrapings can ignite in air, which is exactly what a lighter flint relies on. In bulk it tarnishes but is not dangerous to handle. Cerium compounds have low toxicity and are used in medicines and in some sunscreens, though inhaled cerium oxide dust can irritate the lungs and there are questions about very fine nanoparticles.
As with all rare earths, the environmental burden is in extraction and separation, with acidic waste and mildly radioactive tailings at some mines. Cerium oxide nanoparticles used as diesel additives are released into the air, and researchers are studying where they end up. On the positive side, cerium-based catalysts and polishes have replaced more harmful materials in several industries.
Did you know?
- Cerium is about as common in the Earth's crust as copper, making it the most abundant of the rare earth elements.
- Cerium was named after Ceres, which was discovered in 1801 and is now classed as a dwarf planet.
- The spark from a cigarette lighter comes from a cerium-rich alloy called mischmetal that ignites when scraped.
- Cerium oxide is the polish used to finish most smartphone screens and precision lenses.
- Cerium is the only lanthanide that easily forms a stable ion with a charge of +4.
More in the lanthanides
The nearest neighbours of cerium in the family, by atomic number.
See all 15 lanthanides on one page, or browse all 118 elements.
Frequently asked questions
What is cerium used for?
Its oxide is the standard polish for glass, from phone screens to telescope mirrors, and it stores and releases oxygen inside catalytic converters. Cerium is also the main ingredient in lighter flints, a decolouriser and UV blocker in glass, a fuel additive, and a strengthening addition to some aluminium alloys.
Is cerium rare?
No. Despite being a rare earth element, cerium is about as abundant in the crust as copper and is the most common of the lanthanides. The label rare earth dates from the eighteenth century, when the minerals containing these elements seemed scarce and were hard to separate.
Is cerium toxic?
Cerium compounds have low toxicity and cerium salts have even been used in medicine. The main hazards are physical: finely divided cerium metal ignites in air, and breathing cerium oxide dust over long periods can irritate the lungs. Normal contact with polished glass or lighter flints poses no risk.
Why is cerium named after Ceres?
Ceres, the largest body in the asteroid belt, was discovered in 1801 and was big news when cerium was identified two years later. Berzelius and Hisinger followed the fashion of naming new elements after newly found celestial bodies, as had been done with uranium and would soon be done with palladium.
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Written by Anthony. Updated September 2026. Numerical data from Periodic-Table-JSON (CC BY-SA), cross-checked against the Cerium reference article. Spotted an error? Tell us.