A multianalytical approach to study the Phoenician bronze technology in the Iberian Peninsula—A view from Quinta do Almaraz

Phoenician settlers were responsible for very important changes on the metallurgical practices used in the Iberian Peninsula during the first half of the 1st millennium BC. The study of copper-based artefacts from the Phoenician settlement of Quinta do Almaraz (Portugal) was used to characterise exogenous influences on local metallurgy. Micro-EDXRF analyses on cleaned metal surfaces identified copper, low-tin bronze (2.2 to 8.1 wt.% Sn) and leaded bronze artefacts (4.6 to 5.9 wt.% Pb). Additionally, significant impurities of iron were found (0.15 to 1.3 wt.% Fe) suggesting the smelting of copper ores under a strong reducing atmosphere. SEM-EDS and optical microscopy identified polygonal and nearly equiaxial α-copper grains with annealing twins and slip bands, which indicate comprehensive manufacturing procedures involving hammering and annealing operations. Vickers microhardness testing was utilised to assess the mechanical performance attained by ancient metallurgists. The microstructural features and microhardness values showed that a common approach was to workharden the artefact with a strong final hammering (discernible by high density of slip bands), although some examples also benefited from a highly skilful usage of the forging plus annealing cycles (uniform and very small grain size). Comparison with coeval collections from the southwestern Iberian Peninsula has established that the metals in the settlement of Quinta do Almaraz were produced by a different technology from the indigenous metallurgy.