The application of Sr and Nd isotopes to decipher the source of Nabataean bronze coins collected in Israel

This study regards Strontium and Neodymium isotopic analysis of 40 copper-based coins, belonging to the Nabataean Kingdom and coming from the Israel Antiquities Authority at the Israel Museum (Jerusalem). The Nabataean Kingdom was a powerful political entity, which flourished in modern-day Jordan, Israel and Syria between the 4th century B.C.-106 A.D. The Nabataeans were a nomadic tribe, expert in trades and able to control vast trading networks. The elements concentration in the coin-solutions is analysed using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). The isotopic compositions of Sr and Nd are measured on TIMS (Thermal Ionization Mass Spectrometry) and MC-ICP-MS-“Nu Plasma” (Multi-Collector Inductively Coupled Plasma Mass Spectrometer). Lead isotopes are commonly used to trace metal provenance source. They are good geochemical tracers but sometimes they show uncertainty to join the metal to ore deposits, probably because of mixing/re-melting processes. The potential use of Sr and Nd isotopes as geochemical tools («fingerprints») has not yet been explored, due to the low elements' concentrations in metals. However, the ubiquitous geological database of the Sr isotopes and the Nd resistance to the weathering, prompted me to use them to investigate the Nabataean copper archaeometallurgy. The results show that Sr isotopes can trace the metal provenance and when combined with Pb’ ones may represent a more effective tool. Nd isotopes are not easy to measure, but when it’s possible they are also useful for this aim. The simultaneous application of these isotopes, together with chemical elemental analysis, represent the strength of this provenance study.