History
(Magnesia, district in Thessaly) Compounds of magnesium have long been known. Black
recognized magnesium as an element in 1755. Davy isolated it in 1808 and Bussy prepared it
in coherent form in 1831. Magnesium is the eighth most abundant element in the earth's
crust. It does not occur uncombined, but is found in large deposits in the form of
magnesite, dolomite, and other minerals.
Sources
The metal is now principally obtained in the U.S. by electrolysis of fused magnesium
chloride derived from brines, wells, and sea water.
Properties
Magnesium is a light, silvery-white, and fairly tough metal. It tarnishes slightly in
air, and finely divided magnesium readily ignites upon heating in air and burns with a
dazzling white flame.
Uses
Uses include flashlight photography, flares, and pyrotechnics, including incendiary
bombs. It is one third lighter than aluminum, and in alloys is essential for airplane and
missile construction. The metal improves the mechanical, fabrication, and welding
characteristics of aluminum when used as an alloying agent. Magnesium is used in producing
nodular graphite in cast iron, and is used as an additive to conventional propellants.
It is also used as a reducing agent in the production of pure uranium and other metals
from their salts. The hydroxide (milk of magnesia), chloride, sulfate (Epsom salts), and
citrate are used in medicine. Dead-burned magnesite is employed for refractory purposes
such as brick and liners in furnaces and converters.
Compounds
Organic magnesium is important in both plant and animal life. Chlorophylls are
magnesium-centered perphyrins.
The adult daily nutritional requirement, which is affected by various factors include
weight and size, is about 300 mg/day.
Handling
Because serious fires can occur, great care should be taken in handling magnesium
metal, especially in the finely divided state. Water should not be used on burning
magnesium or on magnesium fires.
Sources: CRC Handbook of Chemistry
and Physics and the American Chemical Society.
Last Updated: 12/19/97, CST Information Services Team
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