Kryptonite discovered

it doesn't glow green or absorb superman's power, but it does have the same chemical composition as described in the movie superman returns. the stone was discovered in a Siberian mine and was not found to match any other type of rocks, and when analyzed it was found to be made of sodium lithium boron silicate hydroxide which is the same composition wrote under the rock that lex luthor steals from the museum in the movie. scientists were amazed when they found that out. also the rock was found to glow orange-pink when exposed to ultraviolet rays.

'Kryptonite' discovered in mine (via BBC news)