Aluminum

Aluminum

by

Jenifer Gilin

Aluminum is one of the most abundant element on earth, and its oxide is present in clay, kaolin and many other mineral formations. For economic reasons, aluminum is almost exclusively produced from bauxite, which is a residual clay formed in tropical regions by the chemical weathering of basic igneous rocks. It contains 55 to 65% aluminum oxide (alumina) together with varying amounts of iron oxide, silica and titanium oxide.

Ancient Greeks and Romans used aluminium salts as dyeing mordants and as astringents for dressing wounds; alum is still used as a styptic. In 1761 Guyton de Morveau suggested calling the base alum alumine. In 1808, Humphry Davy identified the existence of a metal base of alum, which he at first termed alumium and later aluminum. Friedrich Whler is generally credited with isolating aluminium (Latin alumen, alum) in 1827 by mixing anhydrous aluminium chloride with potassium. As the metal had first been produced two years earlier by Danish physicist and chemist Hans Christian can also be listed as its discoverer. Further, Pierre Berthier discovered aluminium in bauxite ore and successfully extracted it. Frenchman Henri Etienne Sainte-Claire Deville improved Whler’s method in 1846, and described his improvements in a book in 1859, chief among these being the substitution of sodium for the considerably more expensive potassium. Aluminium is a soft, durable, lightweight, malleable metal with appearance ranging from silvery to dull gray, depending on the surface roughness. Aluminium is nontoxic, nonmagnetic, and nonsparking. It is also insoluble in alcohol, though it can be soluble in water in certain forms. The yield strength of pure aluminium is 711 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminum has about one-third the density and stiffness of steel. It is ductile, easily machined, cast, and extruded. It is often said that Aluminum has had a relatively brief history, and under the name Aluminum it is certainly true. But using aluminum for its properties in compounds (some sources reckon) started at around 5300 BC. It is thought that potters in ancient Persia made their strongest cooking vessels from a clay that consisted largely of aluminum silicates. Aluminum compounds are thought to have been used more by the Egyptians and Babylonians around 4000 years ago as fabric dyes and cosmetics. Despite these uses in the very far past the element aluminum itself wasn’t discovered or named until the early 1800’s when Sir Humphrey Davy established its existence, but even he was unable to actually make any. Just over 10 years later a French scientist discovered hard, red clay containing over 50% aluminum oxide in southern France.

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Aluminum