Ivory, a hard, fine-grained, creamy-white substance resembling bone. The teeth of most animals consist largely of ivory. It is usually called dentin when referring to teeth, and ivory when used as an article of commerce. Commercial ivory includes the tusks of the elephant, hippopotamus, walrus, narwhal, and a few other animals. The tusks of the elephant and narwhal are incisors. Those of the hippopotamus and walrus are canines.
Ivory is composed largely of calcium phosphate, organic matter, and water. It takes a high polish, can be sawed or filed readily, and possesses great elasticity, or springiness. Ivory tends to crack, however, when exposed to sudden changes in temperature.
The best ivory, obtained from the African elephant, is a translucent white. Indian elephant ivory is opaque with a yellowish shade. An elephant's tusk is usually solid for about half of its length, but the base is thin and of little commercial value. The tusks of other animals are much shorter than those of the elephant, and usually of inferior quality.
Ivory has been used for inlay work on fine furniture, and for such articles as knife handles, bracelets, and chessmen. Artisans of China, Japan, and India have long been noted for their carved ivory statuettes, fans, and ornaments. Ivory has also been used on the keys of expensive pianos and for billiard balls. For most purposes, however, ivory has been displaced by such substitutes as plastics, bone, and vegetable ivory.
The quest for ivory dates from prehistoric times. Ivory is often mentioned in the Old Testament, and it was used for ornamental work in the early civilizations of Egypt, Assyria, Babylonia, Crete, and Cyprus. Great quantities of ivory were used by the early Greeks and Romans. During the Renaissance, ivory was widely used for caskets, statuettes, crucifixes, and inlay work. A significant international trade in ivory began in the 17th century.
By the mid-20th century, the ivory trade had diminished, partly because of substitutes, and partly because of the scarcity of elephants and the establishment of game preserves in Africa. Continued demand for ivory in some parts of the world, however, led to widespread poaching, an illegal ivory trade, and the near extinction of the elephant.
In 1990 an international ban on the trade of raw ivory went into effect. In 1999, however, as permitted by a United Nations convention on endangered species, several African nations conducted a one-time sale of stockpiled ivory.