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- Compositional and microstructural outlook of grave goods from Anta do Malhão and Soalheironas (Portugal): the diachronic use of arsenical copper in southwestern Iberian PeninsulaPublication . Valério, Pedro; Silva, Rui J. C.; Soares, António; Araújo, Maria Fátima; Cardoso, João LuísAlthough in recent years the prehistoric metallurgy of southwestern Iberian Peninsula has become increasingly well understood, the southernmost region still requires additional research. This work presents the technological study of artefacts from burial contexts located in this area, namely the necropolises of Anta do Malhão and Soalheironas (Algarve region). Typologies of metalwork and pottery ascribe the single inhumation at Anta do Malhão to a late phase of the “Ferradeira Horizon” (last quarter of the 3rd millennium BC), while assigning the necropolis of cists at Soalheironas to an earlier phase of the Middle Bronze Age (1st half of the 2nd millennium BC). The elemental and microstructural composition of artefacts was established by micro-energy dispersive Xray fluorescence spectrometry, optical microscopy and scanning electron microscopy with X-ray microanalysis. Results show artefacts made of arsenical copper alloys (2.01–3.40% As) with very low iron content (< 0.05% Fe). The microstructures display deformed equiaxed grains with annealing twins and slip bands, evidencing cycles of hammering and annealing, followed by a finishing hammering operation. The integration of results in the prehistoric metallurgy of southwestern Iberian Peninsula suggests a shared technological tradition, while a more comprehensive discussion discloses important developments involving the increased production of strainhardened tools and weapons, together with a rising substitution of the copper metal by arsenical copper alloys from the 3rd to the 2nd millennium BC.
- Compositional and microstructural characterization of grave goods from Anta do Malhão and Soalheironas: an insight into the diachronic use of arsenical copper from the 3rd to the 2nd Millennium BCPublication . Valério, Pedro; Silva, Rui J. C.; Soares, António; Araújo, Maria Fátima; Cardoso, João Luís
- Novos dados sobre a proveniência do cobre de LeceiaPublication . Valério, Pedro; Cardoso, João Luís; Alves, Luís Cerqueira; Soares, António; Araújo, Maria FátimaThe archaeological site of Leceia is a Chalcolithic settlement with one of the largest amounts of metal artefacts in the Lisbon peninsula, although the absence of ores and smelting remains suggests that local metallurgical operations were essentially related to the last stages of the chaine opératoire, namely the casting and forging of artefacts. In fact, the local archaeological record shows several ingots including axe‑ingots, some of which bear clear traces of sectioning. Five of these ingots were analysed to establish their elemental compositions and Pb isotope signatures in order to identify the possible sources of copper used in their manufacture. Elemental results identified copper with variable contents of arsenic (up to 2.94 wt%) and very low amounts of other impurities, which compares well with the composition of local objects. Pb isotope ratios are also in line with the values previously obtained for copper prills and objects from Leceia, supporting the likely use of these ingots for the casting of local artefacts. Moreover, the most likely candidates for supplying the metal based on in the ingots analysed are copper deposits located in the Linares‑La Carolina mine district and also, but to a lesser extent, in mines located in the Los Pedroches Batholith and the South Portuguese Zone. This evidences a long‑distance copper trade between the Portuguese Estremadura and the Southern Iberian Peninsula and implies multiple trade connections of Chalcolithic communities inhabiting this region.
- The supply of copper to the settlement of Leceia (Portugal) and the Estremadura region during the third millennium BCPublication . Valério, Pedro; Cardoso, João Luís; Alves, Luis; Soares, AntónioThe Chalcolithic settlement of Leceia (Portugal) has one of the largest collections of copper artefacts and metallurgical debris in the Portuguese Estremadura. However, the absence of ores and smelting remains suggests that local metallurgical operations were related to the production of artefacts. In fact, the metal assemblage includes several fragments of flat axes, most of them with traces of sectioning, which may have been used as ingots. In order to validate this hypothesis and to identify the copper sources used, elemental, microstructural and Pb isotope characterisation of five axe-ingots was undertaken. The assemblage turned out to be composed of copper with varying amounts of arsenic (0.08–2.94 wt%) and oxide inclusions (Cu2O and Cu-As-O). Some inclusions containing distinct contents of Bi, Sb and/or Sn were also identified, indicating the exploitation of different sources of copper ores. Pb isotope ratios displayed a cluster of four samples (206Pb/204Pb: 18.2378–18.3444) and one outlier with low radiogenic lead (206Pb/204Pb: 17.6625), signatures that compare well with those previously obtained for local artefacts and prills. Euclidean distances identified ore deposits in the Spanish provinces of Huelva and Cordoba as potential suppliers of copper, particularly the supergene copper ores from the mines of Rio Tinto, Cabezadas del Sandino, Preciosa and Quita Pellejo, all of which are located a considerable distance from the settlement of Leceia. Other probable copper sources are located in the mining districts of Linares-La Carolina and Los Pedroches, situated even further away from the Portuguese Estremadura. Consequently, the copper axe-ingots of Leceia, like the previously analysed local artefacts, provide evidence of long-distance trade relations with south-central Iberian Peninsula, which appear to be shared with coeval settlements in Estremadura, such as Vila Nova de São Pedro and Zambujal.