The role of arsenic in Chalcolithic copper artefacts – insights from Vila Nova de São Pedro (Portugal)

Non-destructive characterization of archeological Cu-based artifacts from the early metallurgy of southern Portugal

“…Notwithstanding the limitation imposed by the somewhat limited number of samples investigated, at a first glance, the results seem to point to the absence of any clear relationship between the amount of As and the typological and morphological characteristics of the metal objects under consideration. This circumstance appears to be in contrast with what has been documented in various sites from southern and central Portugal using copper and arsenical copper technology, such as Atalaia do Peixoto, Castro dos Ratinhos, São Pedro, Três Moínhos, Tholos de Caladinho (Orestes Vidigal et al 2015), Zambujal (Müller et al 2007), Leceia (Müller and Cardoso 2008a), and Vila Nova de São Pedro (Müller and Soares 2008b;Pereira et al 2013), and where correlations between As concentration and certain artifact types have been identified and interpreted as the evidence of an intended selection made by the ancient metallurgists of the alloys produced. On the other hand, similarly to what has been detected at VNMF and EST, chemical analyses on metal artifacts found in the neighboring region of Andalusia, such as at Cabeço Juré and La Junta e Valencina de la Concepción, did not allow detection of any link between As contents and specific metal typologies and functionalities (Bayona 2008), thus attesting a controversial reality, whose interpretation appears to not be unanimous among researchers.…”

Microanalytical study of copper ores from the Chalcolithic settlement of São Pedro (Portugal): Copper production in the south‐western Iberian Peninsula

“…The selection of As‐rich raw materials could be made for aesthetic reasons rather than functional purposes due to the apparent inability of those metallurgists to exploit the hardening capability of As fully (e.g., Pereira et al . ; Valério et al . ).…”

“…The association of arsenical Cu alloys with certain articles, such as daggers and arrowheads, is another distinctive trait of this early metallurgy. The selection of As-rich raw materials could be made for aesthetic reasons rather than functional purposes due to the apparent inability of those metallurgists to exploit the hardening capability of As fully (e.g., Pereira et al 2013;Valério et al 2017). Other authors suggest that the differences in As content between different types of artefacts might be explained by the higher probability of recycling of metals collected in settlements when compared with objects chosen to be deposited in graves (Rovira and Delibes de Castro 2005; Rovira and Montero-Ruiz 2018).…”

“…Early artefacts were composed of Cu with varying contents of arsenic, an alloying element that induces significant changes to the metal, such as a better castability, higher strain hardening and a silvery colour. However, it is still unclear whether the arsenical Cu alloy (Cu with more than 2 wt% arsenic ) was intentionally produced and, if so, whether it would be used as a prestige symbol owing to its unique colour or be chosen for more practical reasons such as the higher hardness of hammered artefacts (Müller et al 2007;Müller and Cardoso 2008;Müller and Soares 2008;Pereira et al 2013;Valério et al 2017).…”

An insight into the organisation of metal production in the Argaric society

“…These data suggest that the innovation of tin bronze was not intended to increase proficiency or production, but rather for purposes of ostentation, being tin is scarcer than copper and having trade and aesthetic value Murillo-Barroso et al, 2014). Colour may have also played an important role in the development of arsenical copper and bronze production in Europe (Keates, 2002;Pereira et al, 2013). Differences in trace element compositions between arsenical copper and bronze are not detected.…”