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ivory, type of dentin present only in the tusks of the elephant. Ivory historically has been obtained mainly from Africa, where elephant tusks are larger than they are in Asia, the second major source, and much dead ivory was and continues to be taken from remains of extinct mammoths found in Canada, Alaska, and Siberia. African tusks of about 55 lb (25 kg) each are common, although tusks of more than 200 lb (91 kg) have been recorded.
In commerce, ivory is classified as live (from recently killed animals) and dead (tusks long stored or on the ground for extended periods and lacking the resilience of live ivory). Ivory may be of a soft or hard variety; the former type is more moist, cracks less easily than the brittle hard ivory, and is easier to work. In the West, soft ivory, obtainable primarily from the eastern half of Africa, was preferred to the hard variety from W Africa. Green, or guinea, ivory denotes certain types of ivory obtained from a wide belt in north central Africa, from the east to the west coasts. At various periods in Africa, native peoples, Arabs, and European colonial powers dominated the trade (now banned) in ivory. Zanzibar, Antwerp, London, and Hong Kong have been major centers of ivory commerce.
Natural substitutes (e.g., tagua, or vegetable ivory) for ivory or near equivalents have long been used. The tooth structure of many other animals, such as the hippopotamus, walrus, narwhal, sperm whale, and wild boar, is also often called ivory.
Uses of Ivory
Ivory is prized for its close-grained texture, adhesive hardness, mellow color, and pleasing smoothness. It may be painted or bleached, and is an excellent material for carving. Large surfaces suitable for veneer are obtained by cutting spiral sheets around the tusk. Commercial uses of ivory include the manufacture of piano and organ keys, billiard balls, handles, and minor objects of decorative value. In modern industry, ivory is used in the manufacture of electrical appliances, including specialized electrical equipment for airplanes and radar.
Its use in art dates back to prehistoric times, when representations of animals were incised on tusks. Objects in ivory were created in ancient Egypt, Assyria, Crete, Mycenae, Greece, and Italy, and there are many biblical references to its use at least from the time of Solomon. Large Greek statues, such as the Athena of Phidias, were made in gold and ivory (chryselephantine), and the Romans made lavish use of ivory in furniture, implements of war, and decorative items. A considerable number of diptychs and panels in ivory, given as gifts primarily by Roman consuls, still exist. Ivory plaques, diptychs, boxes, liturgical objects, book covers, and small statues were made in great numbers from early Christian times until c.1400, but the production of these objects declined thereafter. Ivory carving was practiced both in W Europe and in the Byzantine Empire. In India, ivory carving and turning has been done from ancient times. In China and Japan ivory has been used for inlay and small objects, especially for statues and carvings of small size and great precision and beauty of detail. In the last few centuries in Europe and North America, ivory has been employed to decorate furniture, for small statues, and occasionally as a surface for miniature painting.
The Threat to Elephants
the tooth substance, or dentin, that composes the tusks of elephants (African elephant, Indian elephant, and mastodon). Ivory is a valuable manufacturing material. Durable and homogeneous, it is characteristically white with a yellowish cast. Ivory yields well to carving, grinding, and polishing; after plasticization it can be bent, so that it can be formed into sheets up to 0.4 m wide. The best-quality ivory is exported from Africa (tusks reaching a length of 3 m and a weight of 100 kg) and India (tusks reaching a length of 2.5 m long and a weight of 75 kg). Ivory is highly valued on the international market.
In the USSR many mastodon tusks have been found in northeastern Siberia in layers of permafrost. Since ancient times ivory has been used to make ornaments, as well as objects for everyday and religious use. Ivory is also used in industry. The teeth of sperm whales and the tusks of narwhals and walruses may be used as ivory.