Recent results from a three-year multi-disciplinary project on Ancient Egyptian gold jewellery revealed that items of jewellery from the Middle Kingdom to the New Kingdom were manufactured using a variety of alluvial gold alloys. These alloys cover a wide range of colours and the majority contain Platinum Group Elements inclusions. However, in all the gold foils analysed, these inclusions were found to be absent. In this work a selection of gilded wood and leather items and gold foil fragments, all from the excavations by John Garstang at Abydos (primarily from Middle Kingdom graves), were examined using Scanning Electron Microscopy-Energy Disperse Spectroscopy (SEM-EDS), X-Ray Fluorescence (μXRF), Particle Induced X-Ray Emission (µPIXE) and Double Dispersive X-Ray Fluorescence (D 2 XRF). The work allowed us to characterise the composition of the base-alloys and also to reveal the presence of Pt at trace levels, confirming the use of alluvial gold deposits. Corrosion products were also investigated in the foils where surface tarnish was visually observed. Results showed that the differences in the colour of corrosion observed for the foils are related not only to the thickness of the corrosion layer but also to a multi-layer structure containing the various corrosion products.
To gain further insight into the use of native gold and intentional gold alloys during the Bronze Age in Northwest Portugal, jewellery in the collections of three Portuguese museums was studied using an in-house built portable X-ray fluorescence spectrometer. Among the analysed objects are the Late Bronze Age bracelet from Monte Airoso (Viseu) and the Iron Age tubular bracelet from Regoufe (Aveiro). To shed more light on the manufacture of gold bracelets, have also been analysed all the components (bracelets, wires and bands) of the hoard of Arnozela (Braga), so far incompletely studied. The results obtained show that from the Middle Bronze Age onwards gold containing 8-11 wt.% silver is used, to which gradually increasing amounts of copper seem to have been added over time. These results support a heterogeneous chronology for the components of the hoard of Arnozela and show that the bracelet from Monte Airoso is made from an intentional gold alloy used in the Portuguese area during the Late Bronze Age. On the contrary, the bracelet from Regoufe is made from native gold without addition of copper. This could indicate that at least during a certain period the goldsmiths used both native gold as found and intentional alloys.Two other objects, discussed on the light of the data obtained for the bracelets, complete the study. One of them is one of the two Portuguese Early Bronze Age gold sheet ornaments with cut parallel bands (so-called gargantilha de tiras), found in Braga. Without obvious signs of use-wear like other ornaments of the same type, and made, as expected, with gold hammered into sheet, this ornament is made from an alloy that seems to correspond to a later period using gold from another origin. Finally, the composition of some of the components of the Late Bronze Age-Iron Age string from Malhada (Vila Real), a set of gold decorated plaques made from punched gold sheet by using different and asymmetrical punches, supports the addition of small amounts of copper to gold to produce intentional alloys.
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