How the character is built
The 钅 radical marks this as a metal, and that is not a coincidence of this one character — it holds right across the table. Read the radical first and the element's state at room temperature is already settled. It is 金 (jīn) squeezed into the space beside another component — radicals change shape by position, which is why 金 is hard to spot until you know to look for 钅.
This character is used for the element and little else — you are unlikely to meet it outside a chemistry classroom.
The element itself
Cerium is about as common in the crust as copper, which makes the term "rare earth" thoroughly misleading. It is also the one member of the family that is easy to separate, because it alone will oxidise a step further than the others, changing its chemistry enough that it can be dropped out of solution while its siblings stay put — the first crack in a problem that took a century to finish solving. Its oxide is the standard polish for optical glass.
Where it sits among the 118
First isolated in 1803.
In Chinese history and language
稀土 xītǔ, "rare earth", is one of the few Chinese technical words that now travels untranslated. The place behind it is 白云鄂博 Báiyún'èbó — Bayan Obo, Mongolian for something like "rich cairn" — north of Baotou in Inner Mongolia, where a survey in the 1920s recorded what looked like an iron mountain and nothing more. The rare-earth minerals in it were identified less than a decade later, but the mine that finally opened in the 1950s was opened for the iron, to feed the new steelworks at Baotou, and for a long time afterwards the rare earths went out with the tailings. The shape of an entire industry is legible in that: the world's great rare-earth deposit was found by people looking for something else, and then worked for years by people who still wanted the something else.
Where it comes from in China
Cerium travels with lanthanum out of Bayan Obo and out of the carbonatite bodies at Maoniuping in western Sichuan, where the same sort of carbonate-rich magma rose along the great strike-slip faults that were tearing through the region as India ploughed into Asia. It is the most abundant rare earth in the crust — commoner than copper — and it arrives whether anyone wants it or not, because the ore's proportions were fixed by geology long ago and no amount of demand rearranges them. That surplus is why so much cerium ends up in bulk uses such as glass polishing: it exists, so a use has to be found for it.
The full entry
For stroke order, example sentences, audio and the complete set of meanings, see the dictionary entry.
铈Cerium in the dictionary →Others built the same way
Every one of these carries 钅, and every one is a metal.