A news report yesterday provided us with this information:

A newly-discovered mineral has been found to contain exactly the same elements as the large green crystals that rob the superhero of his powers.

Unlike fictional kryptonite, the real thing at London's Natural History Museum is white and powdery, emits no radiation, and comes from Serbia rather than outer space.

But scientists who analysed the find were astonished to discover that its chemical composition matched a description of kryptonite in the film Superman Returns.

In the 2006 movie, Superman's arch enemy Lex Luthor steals a kryptonite rock fragment from the Metropolis Museum.

On the case are written the words "sodium lithium boron silicate hydroxide with fluorine".

Mineralogist Dr Chris Stanley, from the Natural History Museum, said: "Towards the end of my research, I searched the web using the mineral's chemical formula - sodium lithium boron silicate hydroxide - and was amazed to discover that same scientific name written on a case of rock containing kryptonite stolen by Lex Luthor from a museum in the film Superman Returns.

"The new mineral does not contain fluorine and is white rather than green, but in all other respects the chemistry matches that for the rock containing kryptonite.

"We will have to be careful with it - we wouldn't want to deprive Earth of its most famous superhero!" weightlifter

The unusual mineral was unearthed in Serbia by geologists from the mining group Rio Tinto.

The newly found mineral will not be called Kryptonite but "Jadarite" - because of where it was found in Jarda, Serbia.