Figure 8: Typical X-ray spectra obtained at 20 kV acceleration voltage. The identified elements can be divided in two categories: Cu, Zn, Sn, Ag, Hg, Pb, Au, and Bi that, presumably, compose the coins alloy and C, O, Na, Al, Mg, Si, S, Cl, and Ca that are attributed to external pollution and dust incrusted at the surface of the metal.