About five years ago, the staff at CERN realized there was a thin film of material that was forming on the interior of the LHC. They soon realized that it was actually made up of precious metals.
In fact, this material was a combination of about 90% gold, 10% platinum, and a small balance of rare earth metals.
The thin layer of metals was just four microns thick. However, if it turned out that this metallic coating lined a large portion of the LHC's 27 kilometers of piping, it was estimated that some four metric tons of gold had accidentally been created!
https://www.gainesvillecoins.com/blog/did-physicists-accidentally-discover-a-way-to-make-gold