Non-destructive structural studies of coins from the Uzundara Fortress using X-ray diffraction and neutron tomography

Abstract

The copper Heliocles coin and two silver Demetrius coins dated to the II century BC from the archaeological works of the Uzundara fortress of the Greco-Bactrian Kingdom were studied using non-destructive structural diagnostics methods. The phase analysis of the coins was performed using the X-ray diffraction method. Also, the spatial distribution of the internal components of the coins was investigated by neutron imaging methods. It has been established that the dominant phase of the Heliocles coin is copper, however, a small volume of patina was found. It is mainly represented by tenorite CuO phase. The neutron tomography method indicates a deep penetration of tenorite into the thickness of the coin, and its volume fraction can reach 10% of the total volume. Two Demetrius coins consist entirely of silver. The complex profile of coins due to the features of a coinage was reconstructed. The phase composition, the content of the composite phases and three-dimensional models of the studied coins were obtained.