A new piece of the puzzle: slag and ore analysis to reconstruct the prehispanic smelting technology at the Atacama Desert, Chile

Abstract The Incas appropriated many local metallurgical technologies throughout the Andes, each of which had its unique peculiarities and was based on ancestral knowledge. widespread use tin-bronze during Inca expansion, development mining smelting sites, as well ethno-historical records evidence Incas’ interest in copper smelting, a key activity Andes since ca . 1400 BC. However, little is known about technical parameters achieved by ancient metallurgists changes that occurred expansion. In this paper, we address these through case study Copiapó valley, focusing Viña del Cerro site, one most famous centres southern Andes. Although place architectonically restructured Incas, operations began long before imperial expansion used wind-powered furnaces. We analysed 19 slag 11 ore samples using OM, SEM–EDS, WD-XRF, XRD analyses. Results identified heterogeneous viscous slags, rich SiO 2 (43 wt%) poor FeO (13 wt%). Copper retention high (up to 60 Microstructural analyses indicate slags were formed under unstable oxidising conditions, reaching temperatures ranged between 1000 1100 °C. produced very pure. High-grade ores containing up 69 wt% CuO reduced at combining carbonates (malachite, azurite), halides (buttgenbachite, clinoatacamite), some sulphates (brochantite). propose even relatively unfavourable conditions for formation, generated competent enough extract metal, but not necessarily form liquid slag. These facilitated metallurgists’ thorough knowledge wind flow their ability select right ore. This new information contributes understanding efficiency technology knowledge, skills, adaptability from group integrated into economic networks Empire.