The metal artefacts from the prehistoric walled enclosure of Castelo Velho de Freixo de Numão within the early metallurgy of north-west of Iberian Peninsula

This paper deals with the preliminary results of the typological and analytical study of a collection of copper-based objects found at the site of Castelo Velho (Freixo de Numão). This collection is associated to different contexts from the 3rd millennium BC (Chalcolithic). The analyses, performed by non-destructive X-ray fluorescence (XRF), show that the metals were produced with almost pure copper and arsenical copper (> 2% As). Impurities, such as As (<2%), Fe, Bi, Ag, Sn, Sb and Ni, were also identified, likely due to their presence in the ores used for the production of the objects. The data suggest that the metals from Castelo Velho may be framed within the metallurgical production already known for the Chalcolithic of the North-Western Iberian Peninsula.