Metallurgical analyses in studies on the origin of forged coins from the 11th century in Pomerania (Poland)

Abstrakt

Counterfeit coins in circulation during the early Middle Ages are considered to be products made primarily of copper alloys, often silver-plated or silver-washed. To describe it accurately, it is important that the selected measuring technique accounts for the complexity of such a structure. The application of the right method is of key importance given that the coins in circulation are made using an alloy with an intentionally reduced silver content, which are referred to as imitative coins or coins issued based on original coin stamps. Based on macroscopic and microscopic observations to which a group of 49 coins unearthed at the early medieval site of Pawłówek was subjected to (23 of which showed characteristics of forgeries), four were subjected to a detailed SEM/EDX analysis to identify differences in the chemical composition of the surface of these objects, and then they were tested by XRF fluorescence spectroscopy Based on the findings, it can be concluded that in all these cases, we are dealing with counterfeit coins. On their heavily corroded surface, a top layer of silver was present zonally, with a bronze or brass core underneath.