Scanning electron microscopy and energy dispersive spectrometry analyses of ancient bronze artefacts of the Urartian period from Yegheghnadzor region, Armenia

The results of the analysis on some fragments of bronze belts and a bowl discovered from southwestern Armenia, Yegheghnadzor archaeological site, are discussed. The samples are dated to the 7 and 6 BCE from the Urartian period. The artefacts were corroded, and a multilayer structure was formed. To study the stratigraphy of layers and their composition, the samples were analysed using scanning electron microscopy and energy dispersive spectrometry (scanning electron microscopy (SEM)-EDS) and optical microscopy techniques. The bronze finds appear with the typical incrustations, rich in alloy alteration compounds. Concentrations of copper and tin in the alloys were quantified by SEM-EDS: The pattern and the percentage of the alloy are the same for the belts. Regarding the bowl sample, it is constituted by two foils, perfectly in contact but different in colour, thickness and composition. The results evidenced that only two elements participate in forming alloy composition in the samples: Cu and Sn. The tin content is variable from 7.75% to 13.56%. Other elements such as Ag, As, Fe, Ni, P, Pb, Sb and Zn are lower and more than 1% and can be considered as impurities.