Cesium is an alkali metal that has a bright gold color in its natural solid state. While cesium is considered to be a solid, it has a low melting point and is a liquid near room temperatures. Cesium is the least abundant non-radioactive alkali metal, and is the second most electropositive alkali metal. Cesium has an atomic weight of 132.9054519, a melting point of 83.19 °F, and a boiling point of 1240 °F. Cesium is most commonly used as a drilling fluid for oil.