Lithium does not occur free in Nature, and, even in compounds, is far away from being abundant. The element appears widely in the terrestrial crust with an estimated percentage of the order of 0,004%. The major source of lithium is spudomene, lepidolite, amblygonite, petalite and eucryptite, all of them lithium alumni-silicates. Lithium salts have also been detected in the ashes of many plants, namely tobacco, in the milk, blood or in mineral sources.