Copper plating on an iron artefact from the early medieval site of Peveragno (Piemonte, north western Italy)

Among the iron pyrometallurgical slags and iron artefacts found during the stratigraphically related excavation of an early-Middle age site near Peveragno (Cuneo) in the north-western part of Italy, an object attracted attention due to the presence of a surviving copper plating on an iron core. As copper plated iron object are quite rare and, to our best knowledge, the sample found at Peveragno is the first example found in Italy, we have studied the microchemical structure of the copper-iron interface for this artefact in order to ascertain the copper plated technique used at Peveragno. The microchemical results have shown that the copper layer is characterised by a thickness ranging from 100 to 200 micr., and it must be underlined that the copper layer is continuous 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 and in these latter materials characterised by iron-rich alpha spheroids (20-40 micr.) where very small copper particles are dispersed. 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 phases. Based on these results, a dipping technique can be ruled out and the first results of the copper plating experiments suggest a more sophisticated plating technique.