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
Caesium melts at about 28°C, so it is liquid on a warm day, and it is the most reactive metal there is — it will ignite in air and detonate in water, so it lives sealed in glass. Its one real ore, pollucite, occurs in a handful of granite pegmatites worldwide, and for decades a single deposit in Manitoba supplied nearly all of it. Its greatest role is definitional: the second is no longer a fraction of a day but a fixed number of oscillations of a caesium-133 atom, which means every clock on Earth ultimately answers to this element.
Where it sits among the 118
First isolated in 1860.
Where it comes from in China
Caesium is scarce enough that only a handful of places on Earth have ever yielded it in quantity, and one of them is the Koktokay pegmatite in the Altai of Xinjiang, where it occurs as pollucite. The caesium ion is the largest of any stable metal, which is precisely why it cannot squeeze into ordinary rock-forming minerals and stays behind in the residual melt until the very end of a granite's crystallisation. Almost every caesium mineral on Earth is therefore found in a pegmatite.
The full entry
For stroke order, example sentences, audio and the complete set of meanings, see the dictionary entry.
铯Caesium in the dictionary →Others built the same way
Every one of these carries 钅, and every one is a metal.