Lithium is never found in its pure form in nature, according to the UC Davis ChemWiki. It is found in igneous rocks combined with other elements, such as aluminum, silicon and oxygen, and in salt water as lithium chloride.
Lithium is an alkali metal. This means that it has a single valence electron that is easily given up to form compounds and is, therefore, highly reactive. Extraction of lithium from minerals is achieved by converting the mineral into lithium chloride through a series of reactions and then subjecting the chloride to an oxidation-reduction reaction in an electrolytic cell. This separates the lithium and chloride ions.