Metallurgical production from the Chalcolithic settlement of Moita da Ladra, Portugal

Abstract

ABSTRACTThe Chalcolithic site of Moita da Ladra, on the right bank of the River Tagus, near Vila Franca de Xira (Portugal), was mainly settled during the second half of the 3rd millennium BC. The large amount of metal artifacts and metallurgical remains recovered at the site indicates local metallurgical activities. Chemical and microstructural characterization of 62 copper-based artifacts and 8 metallic nodules from the settlement are presented. Micro-EDXRF, optical microscopy, SEM-EDS and Vickers microhardness testing were applied in this research. Elemental determinations show artifacts containing variable amounts of arsenic. Forty-five percent of the artifacts have an arsenic content at impurity level (As < 2 wt.%), while the remaining items range from 2.0 wt.% to 5.4 wt.% As. Microstructural analysis shows that artifacts were shaped by hammering and annealing cycles, being 33% of the artifacts finished by cold working. Metallic nodules were produced by smelting operations, and are chemically consistent with the analysed artifact collection. Results are compared with those obtained by similar researches carried out on important contemporary materials from the same geographical area (Portuguese Estremadura) and other Iberian regions (Southern Portugal and Western Andalusia).