PIXE analysis of tiara emeralds
This curve - called the energy spectrum - shows the energy distribution of X-rays detected during the irradiation of an emerald by the particle beam of the accelerator AGLAE. One observes the presence of characteristic lines signatures of zinc, rubidium and caesium impurities. Like "DNA" identification, these impurities establish that these emeralds belonging to a crown of Visigoth treasure of Guarrazar (Spain) came from a mine in Tyrol.