<P> Although magnesium is found in more than 60 minerals, only dolomite, magnesite, brucite, carnallite, talc, and olivine are of commercial importance . </P> <P> The Mg 2 + cation is the second-most - abundant cation in seawater (about 1⁄8 the mass of sodium ions in a given sample), which makes seawater and sea salt attractive commercial sources for Mg . To extract the magnesium, calcium hydroxide is added to seawater to form magnesium hydroxide precipitate . </P> <Dl> <Dd> MgCl 2 + Ca (OH) 2 → Mg (OH) 2 + CaCl </Dd> </Dl> <Dd> MgCl 2 + Ca (OH) 2 → Mg (OH) 2 + CaCl </Dd>

The most stable interaction between magnesium and chlorine forms