Iridium

Iridium is a dense, very hard, brittle, silvery-white transition metal of the platinum family, and is the most corrosion-resistant element known to exist. It is used in multiple commercial applications, from increasing the efficiency of polymers, creating high-temperature alloys for use in fusion reactors and other high-temperature environments, to the production of antimatter and antimatter based weapons. It is a very rare material and its only known abundant source is in the Omicron Delta system.