A copper-plated artifact from the early medieval site of Peveragno (north-western Italy)

Among the iron pyrometallurgical slags and iron artefacts found during the stratigraphically related excavation of an early Middle Ages site near Peveragno (Cuneo) in the north-western part of Italy, an object attracted the attention due to the presence of a surviving copper plating on an iron core. Because the copper plated iron objects are quite rare and, to our best knowledge, the sample found at Peveragno is the first found in Italy, we have studied the microchemical structure of the copper-iron interface for this artefacts in order to ascertain the copper plating technique used at Peveragno. The microchemical results have shown that the copper layer is characterised by a thickness ranging from 100 to 200 micron and it must be underlined that the copper layer is continuos on one side of the iron artefact with a complex microchemical structure quite similar to that observed in the so called Ramo Secco bars and in the Aes Rude. Indeed, the presence of iron island dispersed in the copper layer was evidenced as in these latter materials characterised by iron-rich alpha spheroids (20-40 micron) where are dispersed very small copper particles. On the contrary, the opposite copper layer is highly defective and is characterised by a quite different microchemical structure with a very thin interdiffusion layer between iron and copper with a scarce presence of the iron rich micron phases. On the base on these results, it can be ruled out a dipping technique and the first results of the copper plating experiments suggest a more sophisticated plating technique.