This kryptonite is lethal… Thanks to her abuse of a magic ring, Supergirl wakes up one morning to find she …
KILL IT WITH FIRE.

It’s what most individuals are familiar with. Silver Kryptonite is a synthetic form of Kryptonite created by Brainiac from the liquid metal that formed the body of his humanoid avatar.
Kryptonite is the name given to shards of matter cast off from the planet Krypton after its destruction. Large amounts of the substance landed on Earth in October 1989 during a spectacular yet destructive meteor shower which struck Smallville and concealed the arrival of the baby Kal-El and his cousin Kara Zor-El. Green kryptonite is the traditional kryptonite. Kryptonite is a radioactive mineral that made up most of the planet Krypton's structure, including its core. • The Adventures of Superman (1952–1958) featured kryptonite in the episodes "Panic in the Sky", "The Defeat of Superman", "Superman Week", "The Deadly Rock", "The Magic Secret", "The Gentle Monster" and "All That Glitters". Silver Kryptonite induces hallucinations and paranoia into a Kryptonian, as seen in Smallville, Batman and Superman Adventures.