Antimony is a chemical element with symbol Sb and atomic number 51. It is one of the oldest elements in usage with the Ancient Egyptians having used it for make-up (kohl for the dramatic eye effects). The ancient Romans called it stibium, hence its chemical symbol Sb. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). It was established to be an element around the 17th century. The first natural occurrence of pure antimony in the Earth’s crust was described by the Swedish scientist and local mine district engineer Anton von Swab in 1783.
The abundance of antimony in the Earth’s crust is estimated at 0.2 to 0.5 parts per million, comparable to thallium at 0.5 parts per million and silver at 0.07 ppm. Even though Sb is not abundant, it is found in over 100 mineral species. Antimony is sometimes found natively, but more frequently it is found in the sulfide stibnite (Sb2S3) which is the predominant ore mineral.
The principle use of antimony is in flame retardants as antimony trioxide (ATO). ATO is most commonly used as a synergist to improve the performance of other flame retardants such as aluminium hydroxide, magnesium hydroxide and halogenated compounds. ATO is used in this way in many products including plastics, textiles, rubber, adhesives and plastic covers for aircrafts and automobiles. The largest applications for metallic antimony are as alloying material for lead and tin and for lead antimony plates in lead-acid batteries. Alloying lead and tin with antimony improves the properties of the alloys which are used in solders, bullets and plain bearings. The second most common use of antimony alloy is as a hardener for lead electrodes in lead acid batteries. This use is in decline as the antimony content of typical automotive battery alloys has declined by weight as calcium, aluminium and tin alloys are expected to replace it over time. An emerging application is the use of antimony in microelectronics.