Study of an Iron Age Gilded Silver Earring by XRF, SEM-EDS and Multifocus OM

Abstract

The use of gold for artefact productions underwent substantial developments during Iron Age in western Europe, with the diversification of alloy compositions and the introduction of new technologies and aesthetics. This work presents a detailed study of a Late Iron Age earring from the western Iberian Peninsula and a discussion taking into consideration the alloys and technologies used at the time. The earring has a complex structure, composed of block- and strip-twisted wires and granulation. Characterization by multifocus optical microscopy, portable X-ray fluorescence spectrometry (pXRF), micro-XRF and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) were performed to obtain information on the chemical composition and manufacturing techniques. Results show that the earring was manufactured with wires and granules made of a silver-rich alloy, covered with a gold-rich layer 45 μm thick on average, which acted as an external coating making the entire earring resemble gold. This is a rare example of an Iron Age gilded earring, and its detailed study provides further information on the manufacturing solutions adopted by the Iron Age goldsmiths.