Irillium is an element which may occur as an impurity in ryetalyn. The presence of irillium in ryetalyn renders it pharmacologically inert, and useless as a treatment for Rigelian fever.
During a Rigelian fever outbreak on USS Enterprise in 2269, Holberg 917G was scoured for ryetalyn. Initially, the planet's deposits were believed to be useless due to irillium contamination of almost one parts per thousand. However, it was possible there might be a way to couneract the effects of irillium. (TOS: "Requiem for Methuselah")
Page 18 of the Star Fleet Medical Reference Manual describes irillium as having the chemical symbol Im, an atomic mass of 305 for its most stable isotope, and an atomic number of 116. It adds that the element (which is presumably radioactive) was first discovered by Humans in the Sol system's asteroid belt in 2029.
External link[]
- Irillium at Memory Beta, the wiki for licensed Star Trek works