Discovered in: 1860

Discovered by: Robert Bunsen and Gustov Kirchhoff of Germany

Description: Named from the Latin word meaning sky blue (cesium's spectra contains two prominent blue lines), cesium is a shiny silvery metal with a gold tint. Outside of the USA, it is spelled caesium. Cesium is the softest of all metals, about as soft as wax and easily cut with a knife. It is also the most active metal, reacting strongly with air and explosively with water. Cesium will even react with ice, and cesium hydroxide is the strongest base known. It has a very low melting point, and would melt if held in one's hand. Cesium and cesium compounds are used as catalysts and as scavenger metals. It is also used in photoelectric cells, infrared lamps, special glass, and radiation monitoring equipment. Cesium is used in atomic clocks, because of the vibration frequency of the cesium atom. Cesium clocks are accurate to five seconds every 300 years. Cesium, similar to rubidium, has potential for use as a fuel in ion engines. Just burning the metal is a very effective fuel in space (it cannot be used in the atmosphere) being 140 times more efficient than any other known fuel. Cesium replaces potassium in the body, but it has none of potassium's beneficial characteristics. It causes a poisonous reaction in relatively small doses.

Biological Rating: No known benefits for life processes in plants and animals.

Biological Benefits: Cesium has no known biological use.

Percentage Amount in the Human Body: 0.000009 %

Obtained from: Cesium is present in trace amounts in a few minerals. It is obtained chiefly from pollucite, although it also is found in lepidolite as an impurity. It is mined primarily in Canada as well as Zimbabwe.