Appearance
Potassium is a soft, white metal which is silvery when cut but which rapidly oxidises.

Source
Potassium is the seventh most abundant metal and makes up 2.4% of the Earth's crust. Most minerals containing Potassium are only slightly soluble and the metal is difficult to extract from them. Certain minerals, however, such as Sylvite, Sylvinite and Carnalite are found in ancient water beds and Potassium salts can be easily recovered from these huge deposits. Potassium hydroxide (Potash) is mined in several places including Germany and the USA. Potassium is also found in sea water, although in smaller amounts than Sodium.

Uses
The greatest demand for Potassium is the use of Potash in fertilisers. Many other Potassium salts have great importance, including the nitrate, carbonate, chloride, bromide, cyanide and sulphate.

General Information
Potassium is the lightest known metal. It is also one of the most reactive and electropositive of metals, and as it oxidises rapidly in air it must be kept under mineral oil. Its reaction with water is vigorous, it catches fire spontaneously, liberating Hydrogen. Potassium and its salts burn with a violet colour. One of the natural isotopes of Potassium is mildly radioactive, and may be one natural cause of genetic mutation in man.