Kryptonite

An element from the planet Krypton that only exists in small chunks. It currently is one of the few elements that can pose as a harmful substance to Superman. If he comes into contact with him, his steroid - based powers weaken.

Yesterday, there was Green Kryptonite (kills any Kryptonian in minutes) ; Red Kryptonite (temporarily alters any Kryptonian, e.g. renders ant-headed, giant-sized, or evil) ; Blue Kryptonite (only affects Bizarros) ; White Kryptonite (kills all plantlife) ; Jewel Kryptonite (gives mind control to Phantom Zone residents) ; X-Kryptonite (gives Streaky the Supercat his superpowers).

The authors of the comic book Superman portrayed Kryptonite as a metallic chemical element from the planet Krypton. However, the suffix -ite generally denotes a compound. Look on your periodic table - there are no elements ending in -ite.

To make matters worse, the element Krypton, presumably a component of Kryptonite if it were a compound, is an inert gas that does not form compounds under ordinary conditions. Superman's anathema is an imaginary compound masquerading as an element.