Magnesium chloride is an inorganic compound represented by the formula MgCl2, and it exists in various hydrated forms. Anhydrous MgCl2 contains approximately 25.5% elemental magnesium by mass. The hydrated forms of magnesium chloride can be obtained from brine or seawater sources. In its natural mineral state, known as bischofite, it is extracted through solution mining from ancient seabeds, such as the Zechstein seabed in northwest Europe. Anhydrous magnesium chloride serves as the primary precursor for the production of magnesium metal, while hydrated magnesium chloride is the more readily accessible form.