Although in real life, Superman is merely fictional, it appears that one element from his world IS real.  Researchers have unearthed an element that bears an uncanny resemblance to the make up of the green rock from the movie Superman Returns.  Although the elemental makeup of the material is nearly identical, it unfortunately doesn’t give off the emerald green glow of the made up stuff.

“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 Luther from a museum in the film Superman Returns.

“The new mineral does not contain fluorine (which it does in the film) and is white rather than green but, in all other respects, the chemistry matches that for the rock containing kryptonite.”

Source: BBC News