Kryptonite, which robbed Superman of his powers, is no longer the stuff of comic books and films.
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.
The substance has been confirmed as a new mineral after tests by scientists at the Natural History Museum and the National Research Council in Canada.
But instead of the large green crystals in Superman comics, the real thing is a white, powdery substance which contains no fluorine and is non-radioactive.
The mineral, to be named Jadarite, will go on show at the the Natural History Museum at certain times of the day on Wednesday, April 25, and Sunday, May 13.
