Early metallurgy in Sardinia: characterizing the evidence from Su Coddu

Abstract

This paper contextualizes analyses of a collection of metal artifacts and ostensible metallurgical slag from the prehistoric settlement of Su Coddu in south-central Sardinia (ca. 3400–2850 BCE). To characterize the types of metals and associated alloys utilized by the earliest residents of Su Coddu, two pins and an unshaped lump of unknown composition were analyzed using portable XRF spectrometry. In addition to metal artifacts, a large quantity of putative slag was discovered at the site that is consistently cited as the earliest evidence of in situ smelting in prehistoric Sardinia. To reconstruct firing temperatures and characterize mineral phases, four samples of the overfired material were selected for thin section petrography and powder XRD analysis. The results of this study indicate that the two pins were made of copper while the unshaped lump was composed of pure lead, making it the earliest lead-based artifact on Sardinia. XRD and petrographic analyses of the fired “slags” reveal that these samples are unrelated to metallurgical smelting and are likely burnt wall coatings whose mineralogical phases correspond with unfired plasters also recovered from the site. These results in combination contribute towards understanding early metallurgical practices in Sardinia and are relevant in reconstructing the events that have shaped the life history of Su Coddu.