Antimony is a lustrous, bluish-white metalloid element with the chemical symbol Sb and atomic number 51 . Though it resembles a metal in appearance, it is extremely brittle and a poor conductor of heat and electricity, exhibiting properties in between those of true metals and non-metals . In nature, it is most commonly found in the mineral stibnite (Sb₂S₃), from which it has been extracted since ancient times . A unique and valuable property of some antimony alloys is their ability to expand upon solidifying, which makes them ideal for casting intricate items like printer type .
The primary industrial use of antimony is as a flame retardant, a role that consumes over half of global production . As antimony trioxide, it is added to plastics, textiles, and electronic casings to prevent the spread of fire . Another major application is in lead-acid batteries, where alloying lead with antimony significantly increases the metal's hardness and mechanical strength for battery grids and plates . From producing ceramic enamels and glass to manufacturing semiconductor components like infrared detectors, antimony's versatility makes it a critical, yet often overlooked, component of modern industry .