Antimony, a chemical element. It exists in two forms, one metallic and one nonmetallic. Only the metallic form is important commercially. Metallic antimony is a lustrous, blue-white, brittle substance. Although weak and soft in the pure state, antimony imparts strength and hardness to alloys. In one of its principal uses, it is alloyed with lead to make storage-battery plates. Other alloys containing antimony include pewter and type metal.

Although all antimony compounds are poisonous, some are used in medicine to treat certain tropical diseases, while others are used as emetics (agents that cause vomiting). Semiconductors, which are used to make transistors and other solid-state devices, are often "doped" with atoms of antimony. (Doping is the deliberate introduction of impurities to impart desired electrical properties to semiconductors.)

Antimony was known and used several thousand years before the Christian Era. It sometimes occurs free (chemically uncombined) in nature, but is usually found combined with sulfur in the ore stibnite. Antimony is mined chiefly in China and Bolivia. The metal is obtained by heating the ore with scrap iron.

Symbol: Sb. Atomic number: 51. Atomic weight: 121.76. Specific gravity: 6.69. Hardness: 3-3.5. Melting point: 1,166.9 F. (630.5 C). Boiling point: 3,182 F. (1,750 C). Antimony has two stable isotopes: Sb-121 and Sb-123. It belongs to Group VA of the Periodic Table and its principal valences are 0, -3, +3, and +5.