Antimony's atomic number is 51 and its symbol is Sb. Elemental antimony does not pose many serious effects on human health. However, once in compound form, this substance can be both toxic and carcinogenic. It is a very shiny and brittle metalloid that has been used since ancient times. It used to be used in medicine and cosmetics, but today its most common use is to produce flame retardants. It is also alloyed with other metals in products such as lead-acid batteries, solders, and bullets. The antimony in these cubes was obtained in pellet form and each cube contains several pieces of this element. The sample is contained within crystal clear Lucite acrylic.