Caesium: Characteristics
The most electropositive stable metal, and its useful salts
What this tab covers The supply and physical characteristics of the commodity. Supply: current production, inventories and stocks, capacity utilisation, geographic and producer concentration, how fast supply responds to price, the project pipeline and capital spending, and logistics and export flows. Material: the physical and chemical properties that set its grade, price and end uses (for example purity and conductivity for metals, API gravity, sulfur and energy content for fuels, moisture, protein and fibre quality for crops).Supply volume characteristics
| Characteristic | Figure | What it means | Source |
|---|---|---|---|
| Current production volume | not published; tonnes to low hundreds of tonnes of cesium compounds a year (no official data) | USGS publishes no world production figure. Mined supply comes from Tanco (Canada, intermittent in 2025), Bikita tailings (Zimbabwe, shipped to China) and stockpiles. US use is no more than a few thousand kilograms of chemicals a year. | USGS MCS 2026, Cesium |
| Inventory and stock levels | about 11,000 t of cesium formate brine in circulation; 5% replaced a year | The largest stock is in use: rented formate drilling brine, of which about 85% is recovered after each well. Producers also hold pollucite stockpiles at Tanco and former mines, but tonnages are not published. There is no exchange stock and no US government stockpile. | USGS MCS 2026, Cesium |
| Capacity utilisation | not published | No capacity or utilisation data exist. Tanco produced only intermittently in 2025, which implies low use of mine capacity, while Sinomine's cesium and rubidium segment revenue rose 50% in H1 2025, which suggests refining capacity was well used. | USGS MCS 2026; Asian Metal (Aug 2025) |
| Geographic and producer concentration | one dominant company (Sinomine, owner of Tanco and Bikita); HHI not computable | No country production data exist, so an HHI cannot be calculated. Producers of cesium products are Canada, China, Germany and Russia. Reserves in Australia, Canada, China and Namibia total under 200,000 t Cs2O. | USGS MCS 2026; Sinomine disclosures |
| Supply elasticity | very low: few pollucite deposits; new supply depends on lithium projects | Bikita's pollucite ran out in 2018 and Sinclair's in 2019. New supply needs lepidolite or spodumene lithium projects to add cesium circuits, which stalled when lithium prices fell. Formate recycling (85% recovery) cushions demand swings. | USGS MCS 2026 |
| Project pipeline and CapEx | exploration and feasibility only; no committed capacity | Projects in Canada (e.g. Case Lake), Laos (cesium-bearing clays), Namibia (Karibib, 3,100 t Cs measured and indicated, in administration from end-2024) and the US. No CapEx or start dates published. | USGS MCS 2026 |
| Logistics and export flows | not tracked in trade data; shipped as salts in kilogram to tonne lots | Cesium has no dedicated HS code and is reported under 'alkali metals, other' and generic salt codes. Bikita tailings move to China for processing; refined compounds move from China and Germany. Metal is shipped sealed in glass or steel ampoules under argon because it ignites in air. | USGS MCS 2026, Cesium (tariff codes) |
Material characteristics Metal / hard commodity
Cesium is the most electropositive stable metal. It melts just above room temperature and reacts violently with water and air. Commercial value lies in its salts: very dense formate brines, cesium promoters in catalysts, cesium iodide scintillators and the cesium-133 atomic transition that defines the second. Purity and the specific compound matter more than any mechanical property.
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Purity / grade | Metal sold at 99.8% and 99.98% (metal basis); salts at 99.9% | Sets price: 1 g ampoule $104 at 99.8% vs $132 at 99.98% (2025) | USGS MCS 2026 |
| Ore grade | Pollucite typically 5-32% Cs2O | Determines which deposits are economic; few exceed this range | USGS MCS 2026 |
| Melting point and density | about 28.5 °C; about 1.93 g/cm3 (indicative, standard handbook values) | Liquid near room temperature; must be shipped sealed under inert gas | CRC Handbook of Chemistry and Physics (indicative) |
| Formate brine density | up to about 2.3 t/m3 (specific gravity 2.3) | Controls pressure in deep high-pressure, high-temperature wells without solids | Asian Metal 2025, via content_v2 |
| Atomic transition frequency | Cs-133 hyperfine transition 9,192,631,770 Hz | Defines the SI second; basis of primary atomic clocks for GPS and telecoms | BIPM SI Brochure, 9th ed. 2019 |
| Electropositivity / reactivity | More electropositive than rubidium | Makes cesium the preferred promoter in some catalysts and photoemissive uses | USGS MCS 2026 |