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U.S. Geological Survey Open-File Report 2004-1432

Mineral Commodity Profiles: Cesium

Published 2005
Online only
Version 1.0

William C. Butterman, William E. Brooks, and Robert G. Reese, Jr.


Cesium is a very soft, ductile, alkali metal that is liquid at 28.4° C. It is the most electropositive and reactive of the alkali metals and forms compounds with a variety of anions and alloys with the other alkali metals and with gold.

The metal ignites spontaneously in the presence of air and reacts explosively in water. Because of this reactivity, cesium is classed as a hazardous material and must be stored and transported in isolation from possible reactants. It is a relatively uncommon element that can be mined in only a few places in the world. The world’s largest deposit of pollucite, which is the principal ore of cesium, is in a zoned pegmatite at Bernic Lake, Canada, and accounts for more than two-thirds of world reserves. Other reserves are in Namibia and Zambia, although numerous low-grade occurrences are known to exist elsewhere. There are cesium occurrences in pegmatite in Afghanistan, China, and Italy, in hydrous opal in Tibet, and in brines in Chile. Although there are cesium occurrences in the United States, no ore is mined, and the metal and its compounds are produced from imported ores by one U.S. company, the Cabot Corporation (Cabot Specialty Fluids, 2003).

Cesium is used in small quantities in a variety of uses, some of which are experimental or developmental in nature. The current application that requires the most cesium is probably as a specialty high-density component in drilling mud used for petroleum exploration. Cesium also has a wide-spectrum of photoemissive properties whereby electromagnetic radiation, which includes visible light and nearby regions of the radiation spectrum, are converted to electrical current. Thus, cesium is used in television image devices, night-vision equipment, solar photovoltaic cells, and other types of photoelectric cells. Perhaps one of its best known applications is its use in the super-accurate atomic cesium clock that is used as a standard for the world’s timekeeping systems. It is used also in the chemical process industry, primarily as an ingredient of metal-ion catalysts; in medical applications; in the removal of sulfur from crude oil in petroleum refining; and as an ingredient in specialty glasses used in fiber optics and night-vision devices.

The market for cesium is very small and amounts to perhaps less than 25,000 kilograms per year (kg/yr) in the United States, and not much more for the rest of the world. World reserves are vast compared with apparent world demand. The mining and processing of cesium minerals are on such a small scale that environmental hazards or damage caused by the production of cesium are minimal.


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For scientific questions or comments concerning this report, contact William E. Brooks.

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