Be -Sb- is a toxic chemical element with atomic number 51. Antimony is a lustrous grey metalloid, found in nature mainly as the sulfide mineral Stibnite. Although the use of antimony is limited by its toxicity, its compounds have been of fundamental value in chemistry. Antimony compounds are prominent fire retardants found in many commercial and domestic products; certain alloys are valuable for use in solders and ball bearings; and an emerging application is the use of antimony in microelectronics.