NONVACUUM ANALYSES OF SILVER COINS (9TH TO 15TH-CENTURY AD)

Quantitative analyses of silver coins were performed by PIXE with a 2.8 MeV external proton beam. These coins were stamped from 875 to 1456 A.D. mainly by Princes of the Principality of Liège (Belgium). Three series of coins were irradiated at least in four different regions of 0.5 mm2: 17 coins of Hugues de Pierrepont (1203-1229), 27 coins of Englebert de la Marck (1344-1364), and one set of 20 coins belonging to the reigns of 20 other Sovereigns or Princes from Charles le Chauve (869-870) to Jean de Heinsberg (1419-1455). The elements of interest were Ag, Cu, Au, Hg, Pb, Bi, Zn, As and Fe. Each position of the samples was carefully controlled in order to avoid differences in geometrical factors from one analysis to another. All the analyses were made in flat external and bright regions, as to exclude the irradiation of possible inclusions or deposits. Those analyzed regions are then probably the most worn away. The analytical results furnish a possible chronological classification of coins taking into account the relative concentrations of Cu-Pb-Au and the absolute concentration of Au. No means of classification may be expected from Ag or Cu contents (except for the most recent debased coins), nor from traces of Hg and Bi which are only present in a limited number of items. © 1990.