Kryptonite discovered

In Serbia:

The rock — named jadarite — was discovered in a mine in Jadar, Serbia, by the Rio Tinto company and identified by London's Natural History Museum.
[...]
We went to check it out and found that in the 'Superman Returns' movie of 2006, Lex Luthor steals a rock fragment from a museum and it zooms in on the fragment and it lists the chemistry of the mineral and that happens to be exactly the same — or almost exactly the same — as what we had found