Antimony is a chemical element with the symbol Sb (from Latin: stibium) and atomic number 51. It is a lustrous gray metalloid, which means it has properties of both metals and nonmetals. Normally it is mined as the sulfide mineral stibnite (Sb2S3). Much less important is stibiconite (Sb3+Sb5+2O6(OH)) Metallic, pure antimony is rare and was erroneously identified as lead upon its discovery. The Swedish scientist and local mine district engineer Anton von Swab discovered it in 1783 in the MineSala Silvergruva, Sweden in Sala, Västmanland, Sweden.

Antimony compounds were used since ancient times, they were powdered for use as medicine and cosmetics. In predynastic Egypt it was used as an eye cosmetic (kohl) as early as about 3100 BC, when the cosmetic palette was invented. The Roman scholar Pliny the Elder described several ways of preparing antimony sulfide for medical purposes in his treatise Natural History. The intentional isolation of antimony is described by Jabir ibn Hayyan before 815 AD. Modern uses are lead antimony plates in lead–acid batteries, for alloys of lead and tin, additives for chlorine and bromine-containing fire retardants, and in microelectronics.

Antimony is a hard, brittle, silver-white metal with a relatively high specific gravity (~6.7) and a relatively low melting temperature. Used in alloys it hardens the alloy, lowers the melting point, and decreases contraction during solidification.