Magnesium chloride is the name for the chemical compound
with the formula MgCl₂ and its various hydrates MgCl₂ₓ.
Anhydrous MgCl₂ contains 25.5% elemental magnesium by mass. These
salts are typical ionic halides, being highly soluble in water. The hydrated
magnesium chloride can be extracted from brine or sea water.