A bismuth crystal covered with an iridescent oxide surface. Bismuth is a post-transition metal with the atomic number 83. It is generally considered to be the last naturally occurring stable, non-radioactive element on the periodic table, although it is actually slightly radioactive. Bismuth compounds are used in cosmetics, medicines, and in medical procedures. As the toxicity of lead has become more apparent in recent years, alloy uses for bismuth metal as a replacement for lead have become an increasing part of bismuth's commercial importance.Photo: Alchemist-hp