Micro‐EDXRF study of Chalcolithic copper‐based artefacts from Southern Portugal

Abstract

A collection of 39 metallic artefacts recovered in archaeological sites of Southern Portugal was studied by micro‐EDXRF to identify their compositions and the use of metal among ancient communities. Artefacts presented different typologies such as tools (e.g. awls, chisels and a saw) and weapons (e.g. daggers and arrowheads) mostly belonging to 2500–2000 BC. The results show copper with variable amounts of As and very low content of other impurities, such as Fe, Pb or Sb. Moreover, nearly half of the collection is composed by arsenical copper alloys, and an association was found between arsenic content and typology because the weapons group (mostly daggers) present higher values than tools (mostly awls). These results suggest some criteria in the selection of arsenic‐rich copper ores or smelting products. Finally, the compositions were compared to those of other collections from neighbouring regions and different chronology to determine metallurgical parallels. Copyright © 2015 John Wiley & Sons, Ltd.

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.…”

Use of Monte Carlo Simulation as a Tool for the Nondestructive Energy Dispersive X-ray Fluorescence (ED-XRF) Spectroscopy Analysis of Archaeological Copper-Based Artifacts from the Chalcolithic Site of Perdigões, Southern Portugal

“…Indeed, if this had happened, one should admit that the more efficient technology, i.e., Cu–As alloys, would gradually have replaced the less effective one in the archaeological record or, for example, pure Cu. After all, the mixing of pure Cu and Cu–As alloys in archaeological contexts with evidences of early Chalcolithic metallurgy has also been observed in other Iberian sites, such as Zambujal, 44,45 Leceia, 46 and Vila Nova de São Pedro 47,48 in central Portugal; São Pedro, Três Moinhos, Atalaia do Peixoto, Castro dos Ratinhos, Tholos de Caladinho, 49 Moinho de Valadares 1, Mercador, Monte Tosco 1, 50 Outeiro de São Bernardo 51 in southern Portugal; 52 Cerro Virtud, 53 Almizaraque, 54 Carmona, 55 Los Millares, 56 Cabezo Juré 57 in southern Spain; and in western Andalusia. 58,59…”

Middle Bronze Age Arsenical Copper Alloys in Southern Portugal

“…Histograms of the arsenic content of MBA (left) and Chalcolithic (right) metals: (a) southern Portugal (this work; Nunes da Ponte et al ; Henriques et al ; Valério et al 2014); (b) southern Portugal (Orestes Vidigal et al 2015); (c) western Andalusia (Bayona ); (d) Portuguese Estremadura (Müller and Cardoso ; Pereira et al ).…”

“…Data for Chalcolithic metallurgy in southern Portugal are scarce, but artefacts analysed from several sites, namely from São Pedro, Três Moinhos, Atalaia do Peixoto, Castro dos Ratinhos and Tholos de Caladinho (Orestes Vidigal et al 2015), have lower arsenic contents than their MBA counterparts (Fig. (b)).…”

“…In southern Portugal, 40 artefacts recently recovered from MBA funerary structures and domestic contexts disclosed a metallurgy comprising more than 80% of arsenical coppers that exhibited an average of about 4 wt% As (Valério et al ). This suggests a different trend of copper‐based metals, especially considering that the Chalcolithic artefacts from this region point to lower arsenic contents (Orestes Vidigal et al 2015).…”