A silvery metallic element belonging to group 2 (formerly IIA) of the periodic table (see alkaline-earth metals); a.n. 12; r.a.m. 24.305; r.d. 1.74; m.p. 648.8°C; b.p. 1090°C. The element is found in a number of minerals, including magnesite (MgCO3), dolomite (MgCO3.CaCO3), and carnallite (MgCl2.KCl.6H2O). It is also present in sea water, and it is an essential element for living organisms. Extraction is by electrolysis of the fused chloride. The element is used in a number of light alloys (e.g. for aircraft). Chemically, it is very reactive. In air it forms a protective oxide coating but when ignited it burns with an intense white flame. It also reacts with the halogens, sulphur, and nitrogen. Magnesium was discovered by Sir Humphry Davy in 1808.
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