Why does magnesium not occur as a free metal in nature?

Magnesium does not occur as a free metal in nature primarily because of its strong chemical reactivity. It is a powerful reducing agent that readily reacts with other elements, such as oxygen, chlorine, and sulfur, to form stable compounds.1234

Because of this high reactivity, magnesium is found exclusively in the form of compounds in the environment, including carbonates like magnesite and dolomite, as well as various silicates, hydroxides, and chlorides found in rocks, brines, and seawater. Consequently, the extraction of pure magnesium metal from these ores is an energy-intensive process that requires specialized industrial techniques, such as electrolysis or thermal reduction methods like the Pidgeon process.3154