Magnesium

Magnesium, chemical element, symbol Mg; for physical constants see Periodic Table. Compounds of magnesium have been known and used for hundreds of years. It was discovered by Humphry Davy in 1808. The eighth most abundant element in the earth's crust, it is extracted commercially by the electrolysis of fused magnesium chloride taken from sea water or other brines. Magnesium is a light, silvery-white, hard, reactive, metal. It plays an essential role in both plant and animal life. Magnesium and its compounds are used in light metal alloys, incendiary devices, flash bulbs, flares, and in medicine.