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alumina

The Columbia Encyclopedia, 6th ed. | 2011 | Copyright

alumina or aluminum oxide, Al ₂ O ₃ , chemical compound with m.p. about 2,000°C and sp. gr. about 4.0. It is insoluble in water and organic liquids and very slightly soluble in strong acids and alkalies. Alumina occurs in two crystalline forms. Alpha alumina is composed of colorless hexagonal crystals with the properties given above; gamma alumina is composed of minute colorless cubic crystals with sp. gr. about 3.6 that are transformed to the alpha form at high temperatures. Alumina powder is formed by crushing crystalline alumina; it is white when pure. Alumina is widely distributed in nature. Combined with silica and other minerals it occurs in clays, feldspars, and micas. It is the major component of bauxite and occurs in an almost pure form as corundum . Alumina is commercially important. A major use is in the production of aluminum metal. It is also used for abrasives; corundum and emery are widely used, as are artificially prepared alumina abrasives. Trade names for alumina abrasives include Alundum and Aloxite. Alumina is also used in ceramics, in pigments, and in the manufacture of chemicals. Clays containing alumina are used in porcelain, pottery, and bricks. Pure alumina is used in making crucibles and other refractory apparatus. Hydrated alumina is used in mordant dyeing to make lake pigments; it is also used in glassmaking, in cosmetics, and in medicine as an antacid.

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alumina

The Oxford Pocket Dictionary of Current English | 2009 | Copyright

a·lu·mi·na / əˈloōmənə/ • n. aluminum oxide, Al₂O₃, a white solid that is a major constituent of many rocks, esp. clays, and is found crystallized as corundum, sapphire, and other minerals.

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alumina

World Encyclopedia | 2005 | Copyright

alumina (aluminium oxide, Al₂O₃) Mineral used as an abrasive, electrical insulator and furnace lining. Other forms of alumina include corundum, two impure varieties of which are the gemstones sapphire and ruby.

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alumina

Oxford Dictionary of Rhymes | 2007 | Copyright

alumina •beginner, Berliner, Corinna, dinner, grinner, inner, Jinnah, sinner, skinner, spinner, thinner, winner •echidna •Krishna, Mishnah, Ramakrishna •vintner • prisoner • Pilsner •Kitchener • Modena • bargainer •imaginer •Elinor, Helena •milliner •examiner, stamina •epiphenomena, phenomena, prolegomena •alumina, noumena, numina •determiner •mariner, submariner •foreigner • larcener • Porsena •patina • retina • Pristina •Herzegovina • breadwinner •prizewinner •angina, assigner, china, consignor, decliner, definer, Dinah, diner, diviner, forty-niner, hardliner, incliner, Indo-China, liner, maligner, Medina, miner, minor, mynah, recliner, refiner, Regina, Salina, Shekinah, shiner, signer, South Carolina, Steiner, twiner, vagina, whiner •headliner • jetliner • airliner •mainliner • eyeliner • moonshiner •Landsteiner • Niersteiner •Liechtensteiner

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Free newspaper and magazine articles

	Alumina: basic balance between supply and demand.(Inorganics) Magazine article from: China Chemical Reporter; 2/26/2008
	Bauxite and alumina growth. Newspaper article from: Advanced Ceramics Report; 3/1/2002
	Cyanate ester-alumina nanoparticle suspensions: effect of alumina... Magazine article from: Polymer Engineering and Science; 7/1/2011