Claustronium

A super-rare element obtained in mysterious circumstances, and used by Hope Three scientists in their attempts to create an invisible soldier. No samples of claustronium remain; they were either lost during the chaos of the Hope Tower Incident, or were stolen from outside labs while the City Special Forces were drafted in to deal with the rescue operation. It is recorded that under certain kinds of electromagnetic fields, the substance would produce a previously unknown kind of radiation, whose properties were incredibly difficult to isolate.

It is now believed that claustronium could have been some form of Atlantean crystal; in which case claustronium rays would be an alternate name for what is now known as Savant Radiation.