XRF analyses on Greek and Roman copper-based coins from Istros (Romania)

• Compositional data of copper and copper-based alloys coins (6 th -7 th c. AD) using pXRF. • Analyses of 35 Greek, Roman and Early Byzantine coins from recent excavations in Istros (Romania). • Compositional types and trends in monetary issues were diachronically investigated. • Alloys for minting from Greek to Early Byzantine period: impure copper, leaded copper, bronze, Ag-Cu alloy, brass. The paper presents and discusses the results of the X-Ray Fluorescence (XRF) analysis on 35 copper-based coins excavated at Istros (Romania), colony of the Greek city of Miletus in the Black Sea, which became later a part of the Roman Empire. All the analysed items were found during the 2017 archaeological campaign conducted by the team of the University of Bucharest. The archaeological research is focused on a Late Antique insula dated to the 6 th – beginning of the 7 th centuries AD. In parallel with the identification and publication of the numismatic material, it was decided to determine the composition of the coinsby means of X-Ray Fluorescence analysis using a portable spectrometer (pXRF). The results reflect the metal composition after the coins underwent laboratory interventions for patina removal, but it should be emphasised that the state of preservation of the items did not allow in all the cases a complete cleaning. The identifiable items range chronologically from the autonomous period of Istros to the 6 th c. AD. Their composition is discussed in the context of the coins’ chronology, issuing authority/centre/mint, and type, using previous results in order to determine possible trends/specificities, which will be discussed in the larger context of copper-based coins issued in the Greek and Roman world.