The press office of the Natural History Museum must have been beside themselves with this one: asked to analyse an unusual mineral from a mine in Serbia, one of their scientists types the composition he's determined into Google and discovers, via Wikipedia, that it's the same as that for Kryptonite. I'd imagine that 'Scientist discovers new mineral - might be a good source of lithium' would be quite a tricky media sell, whereas "Scientist discovers KRYPTONITE!!!' kind of sells itself.
Rather disappointingly, the chemical resemblance does not lead to much physical similarity:

But the reason why is obvious - it's not really kryptonite at all! This new mineral is described as 'sodium lithium boron silicate hydroxide' (shame on the NHM for describing this as the 'chemical formula' incidentally), whereas the Wikipedia article clearly states that the mineral in Superman Returns is 'sodium lithium boron silicate hydroxide with fluorine'. Just add a little fluorine, and the white and powdery 'Jadarite' will no doubt become green, fluorescent and capable of fending off superheroes with dubious fashion sense.
The NHM press release links to a video about the analysis of the mineral, and there's also going be some sort of live presentation about it which you can watch online tomorrow.

Chris Rowan is a geologist specialising in the dark arts of paleomagnetism, and getting people to pay him to travel to exotic destinations for fieldwork. Having drilled up New Zealand during his PhD, and South Africa in his first post-doc, he now works at the University of Edinburgh.
Anne Jefferson has a love of all things water-related and blends hydrology, geomorphology, geology, and climate change in her work. She has a Ph.D. from Oregon State University and is now an assistant professor at the University of North Carolina at Charlotte.

