# Caesium

A soft alkali metal used by the gram in drilling brines, catalysts and atomic clocks, mined from a handful of pegmatites.

Source page: https://www.materialinsights.org/commodities/cesium/

Tech & minor metals · No. 51

- US critical 2025
 Tech & minor metals · Foundation · Matter

Cesium defines the second in atomic clocks, and its dense brines are rented to oil drillers and mostly returned for reuse.

Chart: Illustration: Caesium

##### Where it comes from

Chart: Map of where it comes from

The main ore is pollucite, holding 5% to 32% cesium oxide, from lithium-rich pegmatites. Mining is almost a single-site affair, with much drawn from old stockpiles and tailings.

##### Three things to know

1. About 11,000 t of cesium formate brine is in drilling use, and only 5% is depleted and replaced each year.
2. Cesium is the most electropositive stable metal: it melts just above room temperature and reacts violently with air and water.
3. Congress set a goal to eliminate cesium-137 blood irradiators in the United States by 2027.

##### The journey

1. 1 **Pegmatite**Zoned granite with lithium minerals
2. 2 **Pollucite**Ore with 5-32% cesium oxide
3. 3 **Digestion**Broken down to sulfate or carbonate
4. 4 **Salts**Formate, hydroxide, iodide and others
5. 5 **End uses**Drilling brines, catalysts, detector panels, clocks
 Covered in [How a chemical process works: reactions, separations, catalysts and flowsheetsChemicals](https://www.materialinsights.org/learn/chemicals/how-chemical-processes-work/)[Heavy inorganics: salt, sulphur, nitrogen and phosphorusChemicals](https://www.materialinsights.org/learn/chemicals/heavy-inorganic-chemicals/)

##### Go deeper pick a tab to open it in full

## Other sections

- [Overview](https://www.materialinsights.org/commodities/cesium/overview/index.md)
- [Correlation](https://www.materialinsights.org/commodities/cesium/correlation/index.md)
- [Extraction](https://www.materialinsights.org/commodities/cesium/extraction/index.md)
- [Production](https://www.materialinsights.org/commodities/cesium/production/index.md)
- [Stocks](https://www.materialinsights.org/commodities/cesium/stocks/index.md)
- [Cycles](https://www.materialinsights.org/commodities/cesium/cycles/index.md)
- [Trading](https://www.materialinsights.org/commodities/cesium/trading/index.md)
- [Movement](https://www.materialinsights.org/commodities/cesium/movement/index.md)
- [Criticality](https://www.materialinsights.org/commodities/cesium/criticality/index.md)
- [Characteristics](https://www.materialinsights.org/commodities/cesium/characteristics/index.md)
- [Emissions](https://www.materialinsights.org/commodities/cesium/emissions/index.md)
- [Relationships](https://www.materialinsights.org/commodities/cesium/links/index.md)