Potassium Potassium, the twentieth most common element in the Universe and the seventh most common on Earth, is a lightweight, soft, silvery-coloured metal, whose name comes from the word potash . The chemical symbol, K, however, comes from the Latin word kalium , which in turn comes from the Arabic word for alkali. Like sodium, potassium is too reactive to occur naturally and is always found in compounds. It reacts even more violently than sodium when exposed to air and water, meaning that demonstrations with potassium can be dangerous. The most common uses of potassium are as potash the compound used in glass-making and as a fertiliser.
Potassium is found in the sea, in rocks and in plants.
It was first obtained from the ashes of plant, as potassium carbonate, known as potash. However, the largest amount of potassium is in sea water. Potassiumsalts are also found among deposits indesert lakes and in ancient desert rocks. Potassium is also found in many volcanic rocks. The pink or white feldspar crystals in granite, for example, are compounds of potassium.