White kryptonite

White kryptonite is a fictional item featured in comic book titles published by DC Comics. It is part of DC's Pre-Crisis Earth-One continuity and relates to the Superman family of comic book titles.

White kryptonite is one of the many altered colored forms of Kryptonite. As a mineral, it was once part of the planetary core of the dead world Krypton and was converted into Green kryptonite after the planet exploded. A volume of green kryptonite passed through a radiation wave in space, which changed its color and altered its properties.

White kryptonite emits radiation that is lethal to all forms of plant life, including micro-organisms such as bacteria. Kal-El kept a supply of white kryptonite inside the Fortress of Solitude and channeled its energy through a specially designed ray for various purposes.

Superman once used white kryptonite radiation treatment to cure his cousin Kara Zor-El/Supergirl after she had been driven into a mentally agitated state after being infected with the artificially created pathogen known as Virus X.