http://news.yahoo.com/s/nm/20070424/od_ ... kryptonite
A mineral found by geologists in Serbia shares virtually the same chemical composition as the fictional kryptonite from outer space, used by the superhero's nemesis Lex Luther to weaken him in the film "Superman Returns".
"We will have to be careful with it -- we wouldn't want to deprive Earth of its most famous superhero!," said Dr Chris Stanley, a mineralogist at the Natural History Museum.
Stanley, who revealed the identity of the mysterious new mineral, discovered the match after searching the Internet for its chemical formula - sodium lithium boron silicate hydroxide.
"I was amazed to discover that same scientific name written on a case of rock containing kryptonite stolen by Lex Luther from a museum in the film Superman Returns," he said.