Investigation of copper slags from the Etrusco-Roman site of Populonia-Baratti (southern Tuscany, Italy)

Populonia was one of the most important metalworking centres in Europe in the 1 st Millennium BC. Archaeometallurgical evidences point to significant production of iron, copper, bronze, lead and silver in Etruscan and Roman times. In the framework of an extensive archaeometallurgical survey in the Baratti area, we have analysed types and modes of occurrence of copper slags in order to define the metallurgical process, and the provenance of smelted metals. Along the shoreline of the Baratti Gulf a large slag deposit occur, at the bottom of which we have observed the presence of abundant copper slags of variable size (from small pieces to large cakes). They form a continuous horizon, extending in width for about 30 metres. Two main types (A-type and B-type) of copper slags with different mineralogical, and textural features, have been identified. They could represent the waste products of a two-stage copper smelting process. Both geochemistry and Pb isotope signature of copper slags are in agreement with provenance of copper from Cu (± Pb, Zn) ores occurring in the nearby Campiglia Marittima mining district.