Caesium: Extraction

Why nearly all cesium comes from one rare ore

The main ore is pollucite, which forms in lithium-rich zoned granite pegmatites alongside lepidolite or petalite. Most pollucite holds 5% to 32% cesium oxide. The ore is mined underground or from old stockpiles and tailings, then digested chemically into salts such as sulfate, carbonate and formate. Cesium is tied to lithium geology. New projects in Canada, Laos, Namibia and the United States aim to recover it as a by-product of lithium or rubidium mining. Lower concentrations exist in Chilean and Chinese brines and in geothermal systems.

Cesium is mined from pollucite in a handful of lithium-rich pegmatites. For decades the Tanco mine in Manitoba supplied most of the world, with Bikita in Zimbabwe and Sinclair in Australia as smaller sources. Bikita's pollucite was depleted in 2018 and Sinclair finished in 2019 (USGS), so supply now depends on Tanco's intermittent output, stockpiles and tailings. Ore is digested in acid and converted to salts. New supply may come as a by-product of lithium mining from lepidolite, spodumene or zinnwaldite, but those projects were still in exploration or feasibility in 2025.

Methods compared

How each method works

Pollucite is mined underground or in small pits from zoned pegmatites, sorted, ground and digested in acid. Cesium is purified by crystallisation and converted to carbonate, formate and other salts. Sinomine controls Tanco and Bikita and is the leading producer.

High-grade ore, but only a few deposits worldwide and several are exhausted.

Old tailings and stockpiled ore at former mines are re-treated to recover cesium. Bikita tailings have been processed for shipment to China in recent years.

Uses mined material, but finite.

Lepidolite and zinnwaldite concentrates carry cesium and rubidium that can be recovered from lithium process liquors. China's Yichun lepidolite district in Jiangxi has cesium-rich deposits. Projects in Canada, Laos, Namibia and the US were in exploration or feasibility in 2025.

Large potential volumes, but only if lithium plants add recovery circuits.

Used cesium formate brine is returned after a well, filtered and re-concentrated for the next job. About 85% is recovered each time, and around 5% of the 11,000 t stock is replaced each year.

Makes a scarce metal reusable; depends on deep-well drilling activity.

By-product supply

Cesium is mainly a primary product of pollucite, but new supply will increasingly be a by-product of lithium mining from lepidolite and spodumene, with rubidium as a co-product. That ties future cesium supply to lithium economics: when lithium prices fell in 2023-2025, lepidolite projects stalled, including the Namibia project that entered administration at the end of 2024 (USGS). Prices of cesium salts rose 6-8% a year in 2024-2025 (USGS catalogue prices).

Who does it: global

Who does it: India

India has no cesium production or reserves. USGS notes low cesium concentrations in Indian geothermal systems. India imports small quantities of cesium compounds for catalysts, laboratories and medical isotopes, and cesium is not on India's 2023 critical list.