Potassium is named from the English potash, pot ashes and was discovered in 1807. The symbol K is from the Latin kahlium, meaning alkali. This metal is the seventh most abundant and makes up about 2.4%, by weight, of the earth's crust. Most potassium minerals are insoluble and it is very difficult to obtain the metal from them. Potassium is never found free in nature, but is obtained by the electrolysis of the hydroxide. Potash is mined in Germany, New Mexico, California, Utah and elsewhere. The greatest demand for potash is in the agriculture industry where it is used for fertilizers. Potassium is an essential element for plant growth and it is found in most soils.