It's not good news for Superman - kryptonite has come out of comic books and into reality.
According to movie and comic storylines, kryptonite takes away the superhero's powers.
Now scientists have found a mineral made up of the same chemicals as Superman's big fear.
But the new discovery doesn't have special powers and it's white - not sparkly green like the stuff that makes the superhero quake.
The mineral was dug up at a mine in Serbia.
The new mineral
Scientists were shocked to discover that the chemicals it contains were the same as those listed for kryptonite in the film Superman Returns.
But that's where the similarities end.
"Instead of something green and spectacular we have something that's white and chalky," said one scientist.
The mineral cannot be called kryptonite because it has nothing to do with krypton, which is a real gas.
Instead, it will be named Jadarite after the place where it was discovered.