Metal flow in the late Bronze Age across the Friuli-Venezia Giulia plain (Italy): new insights on Cervignano and Muscoli hoards by chemical and isotopic investigations

Numerous metal hoards found in the Friuli-Venezia Giulia plain, Northeastern Italy, are archaeologically dated to the Recent and Final Bronze Age. Here, the results of an archaeometric study of the copper-alloy artifacts and ingots from two such hoards (Cervignano del Friuli and Muscoli, Udine) are presented. The mineralogical, metallographic, and chemical analyses of the copper objects indicate that the metallurgical process employed copper derived almost exclusively from chalcopyrite (+/- sphalerite, galena) as ore charge. Distinct typologies of ingots (plano-convex and parallel-surfaces) are characterized by different degrees of metal refining. Tools and weapons are made of carefully refined and compositionally controlled bronze alloys, containing specific proportions of tin. These observations point out a high level of technological knowledge in metallic copper extraction and use. The chemical and lead isotope compositions of most analyzed ingots and artifacts suggest exploitation of copper deposits from the Southeastern Alps, including deposits from the Valsugana area and other mining districts of the Trentino-Alto Adige region. One peculiar sample characterized by a significant Sb content suggests possible mixing with "local" fahlerz copper from Carnia and one other ingot, showing a highly radiogenic lead isotope composition may be interpreted as copper from southern Tuscany or as a mixed metal incorporating a small quantity of copper from northerly Alpine sources such as Mitterberg.