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.