M. Fátima Araújo

EDXRF study of Prehistoric artefacts from Quinta do Almaraz (Cacilhas, Portugal)

Abstract This paper presents a non-destructive analytical study by secondary target energy-dispersive X-ray fluorescence spectrometry of selected artefacts found during excavations carried out since 1988, at the archaeological site of “Quinta do Almaraz”, Estremadura, West Portugal. The analysed collection was composed by metallic artefacts (fibulae, fish-hooks, needles, buckle, tweezers, knives, arrowheads), crucibles, slags and metallurgical residues. The chemical composition of the metallic artefacts have made possible to identify different groups belonging to distinct Prehistoric periods, from the Bronze (bronzes) till the Iron (iron-based alloys) Age. Variation in the Sn and Pb percentages in the bronzes pointed out to the existence of three different metallurgical processes, although they did not present different typological characteristics. Semi-quantitative analysis on fragments of crucibles have permitted to identify particular metallurgical operations, namely the preparation of gold alloys and the remains of the silver cupellation process, which was introduced in the Iberian Peninsula by the Phoenician [Early Metal Mining and Production, Smithsonian Institution Press, Washington, DC, 1995].

Multifocus Optical Microscopy Applied to the Study of Archaeological Metals

Studies on cultural metal artifacts can benefit greatly from microscopy techniques. The examination of microstructural features can provide relevant information about ancient manufacturing techniques, as well as about corrosion/degradation processes. In the present work, advantages of the use of multifocus imaging techniques in optical microscopy for the study of archaeological metals are presented. An archaeometallurgical study of a large collection of bronzes demonstrates the possibility of a microstructural study with no need for sample removal, which is a great advantage in the study of cultural objects. In addition, the study of mounted samples illustrates the advantages of the multifocus technique in the examination of particular corrosion features, with the possibility of three-dimensional reconstructions.