Metallic finds from the Venetic site of M.Calvario, Auronzo di Cadore: a preliminary archaeometric study

We present the first investigation on bronze and lead products found at the Venetic-Roman site (IIB.C.-IIA.D.) of Monte Calvario di Auronzo (BL). Samples, found in secondary layer, are mostly finished artefacts, thin plaques and votive disks, plus semi-worked materials, a bronze heap and a lead ingot. Samples have been studied using SEM~EDS, EMPA, XRPD on alteration patine, lead isotope TMS and carbon isotope AMS spectrometry. Thin plaques are characterized by a Cu/Sn ratio of 10/1 that confers excellent workability and high stress resistance. Votive disks are very malleable as they present a Cu/Sn ratio of 16/1, probably achieved to improve decorative work. The compositions of finished artefacts therefore seem to be according to specific decorative requirements. Bronze heap shows metallic areas (Cu/Sn 10/1) with several diffuse spots of unmelted metallic lead, an absence of dendritic structures, hardening lines and twinnings. The obtained data provide evidence that this object was produced at the site and that a thermal or/and a mechanical treatment followed the smelting process, suggesting the existence of a complete pyrotechnological process at the site of M.Calvario. Pb-isotope analyses of an ingot specimen support this assumption, excluding local provenance of the metal (abundant sulphur ores are located near the sanctuary), therefore it probably reached M.Calvario through trade with the Mediterranean area.