Archaeometric Investigation of Gold Coins (Byzantine Period, Romanus Iii) By Means of Portable Xrf: Characterization and Comparison

Abstract

Some of the ancient materials in museums can only be examined on-site, which requires in-situ analysis techniques. Coins made of precious metals are one of such materials and portable X-ray fluorescence (p-XRF) spectrometry is one of the most preferred technique for gold and silver-based coins that need to be characterized in situ and non-destructively. In this study, a detailed archaeometric investigation was carried out for the gold coins which were unearthed after the excavations in Melik Ahmet Street (Diyarbakır, 1992) and brought to Directorate of Diyarbakır Museum through confiscation. The chemical compositions of the samples were specified by means of portable XRF which was applied on 45 gold coins of the Romanus III period. The main element in the composition was found as gold detected as 93.89% in average. Silver was the most abundant element after gold, however the highest silver rate did not exceed 9% (5.25% in average). Copper and iron were identified respectively in 12 coins (Cu: 1.05-2.46%) and 18 coins (Fe: 0.87-6.5%). Manganese, nickel, titanium, lead, iridium and osmium were seen in one sample each. The hierarchical clustering analysis applied with gold-silver-copper-iron and gold-silver suggested three different groups. The hierarchical clustering analysis was also applied considering the p-XRF data achieved in this study (belonging to the Romanus III period), solidus samples belonging to six Byzantine period emperors, and for the hollow coins belonging to four Byzantine period emperors. Taking into account the distribution, classification and the variations, the coins of different emperor periods were compared.