The mercury content of sulfides shows a regular trend on both local and regional scale in the Skellefte district. For this reason sulfide concentrates from thirteen ore boulders were analyzed for Hg, Zn and Cu. The ratio Hg/Zn in sphalerite and Hg/Cu in chalcopyrite as well as the amount of mercury in pyrite appear to serve well as fingerprints of the boulders.