The element is widely distributed in Nature, being the seventh in abundance order. The ocean water contains about 0,07% of potassium chloride, and it is necessary to evaporate 98% of this to make potassium salts start to crystallize. Potassium can be found in many volcanic rocks, which by disintegration supply the element to the soils and the water. The silicate leucite and glauconite are the commercial sources of potassium. The clays can absorb potassium retaining it in the soil and allowing the plants to use it. The main potassium ores are: the sylvite (KCl), the carnalite (KCl.MgCl2.6H2O), the langbeinite (K2SO4.2MgSO4), and the polyhalite (K2SO4.MgSO4.2CaSO4.2H2O) that can be found in Germany, USA, Canada, Russia, Palestine, Congo, Ethiopia, Brazil and Bolivia.