Uh oh. Superman better be careful. Scientists have apparently found Kryptonite. On Earth. How do they know it is kryptonite? Well from the movie Superman Returns of course :D

In the movie,Lex Luthor steals the Kryptonite from a museum. In the movie, the chemical composition is displayed on the case window in the museum. The recently discovered chemical has a similar chemical composition to the rock stolen in the movie.

I feel bad for Supes.Now every petty criminal is going to try and get the Kryptonite and try to kill him :P
The scientists better make him a shield against kryptonite now.