The first time silver kryptonite appeared in comics, Jimmy Olsen proved it to be a hoax as it had no effect on Superman; however, it later appeared in the television series "Smallville," where it induced intense hallucinations and paranoia, although it did not take away the majority of Superman's abilities. In the "Smallville" incarnation, the storyline suggests that Brainiac laced it with trace amounts of green kryptonite because he was able to stab Clark Kent with the material.
After appearing in "Smallville," silver kryptonite found its way back into comics, and maintained the story of the television series. Silver kryptonite is a synthetic form created from the liquid metal of Brainiac's human avatar. It causes Superman to lose his invulnerability, but he can still use his super speed, super strength, freezing breath and laser eyes.