The arsenical copper smelting tradition of the Vera Basin (Southeast Iberia): New insight from Santa Bárbara and Zájara

• Copper Age (3100-2250 cal. BC) arsenical copper metallurgy from the Vera Basin (Southeast Iberia). • Archaeological assemblage from modern excavations including technical ceramics, slag and copper ores from two settlements. • Archaeometallurgical analyses of metallurgical remains: pXRF, OM, SEM-EDS, and XRD. • Arsenical copper (up to 6% As) is produced by using carbonates, mixed Cu-As minerals, and occasional sulphidic ores. • Two types of open crucibles are linked to smelting and melting activities. The early chronology, important archaeological settlements, and extensive archaeometallurgical remains make the Vera Basin in Southeast Iberia a fundamental area to understand the development of metallurgy. Here we present the analyses of a set of technical ceramics, slag and copper ores from Santa Bárbara (Huércal-Overa, Spain) and Zájara (Cuevas del Almanzora, Spain) Chalcolithic sites (3100-2250 cal. BC) using pXRF, OM, SEM-EDS, and XRD. Technological characterisation and contextual information are integrated with previous work conducted in nearby sites, such as Almazaraque (Cuevas del Almanzora), Las Pilas (Mojácar) and Los Millares (Santa Fe de Mondújar), offering a detailed characterisation of the Vera Basin technological tradition. This technological tradition is characterised by the production of arsenical copper (up to 6 % As) using carbonates, mixed Cu-As minerals, and occasional sulfidic ores from a variety of mines, predominantly Pinar de Bédar and Cerro Minado. The metallurgical operations occurred within the domestic sphere, using simple set ups that yielded good-enough but not optimum efficiency. Copper extraction likely entailed a two-step process, in which metal was first smelted, and the resulting metal prills were subsequently re-melted to produce a bigger mass for casting. This is supported by the characterisation of two types of open crucibles linked to smelting and melting activities, respectively. Both types were made of unusually refractory clays but have morphological features adjusted to their specific functions. (An extended summary of results in Spanish is available as Supplementary Material .)