An old problem in a new light: Elemental and lead isotopic analysis of Luristan Bronzes

Abstract

The emergence and provenance of the Luristan Bronzes has been a subject of interest for many decades. This paper presents the results of elemental and lead isotopic analysis of a series of Luristan Bronzes discovered from recent excavations in the Sangtarashan sanctuary, as well as an extensive comparative study on technology and provenance of the Luristan Bronzes. This study was performed in order to better understand tin bronze production technology in the Luristan region during the Iron Age. It focuses on the artefacts themselves, as no mining or production evidence has been discovered in Luristan so far. For this purpose, 46 samples from different pieces of thin sheet vessels from Sangtarashan were analysed by inductively coupled plasma-optical emission spectroscopy (ICP-OES) for their elemental composition and by multi-collector inductively coupled plasma-mass spectroscopy (MC-ICP-MS) for their lead isotopic composition. The results of elemental analysis showed that tin bronze with variable tin content was used to produce these artefacts. The comparative study of the alloy composition also shows that tin bronze may have been the main material to produce ritual artefacts during the Iron Age of western Iran. Furthermore, the lead isotope ratios of the Sangtarashan artefacts partially overlap with those of different copper ore deposits on the Iranian Plateau, including deposits close to Luristan (such as Deh Hosein) and ore deposits further away, in central and eastern Iran. In fact, the results revealed that it is not possible at this stage in the research to identify one specific ore deposit or region as the source of copper for tin bronze metallurgy during the Iron Age of Luristan. Thus, the research suggests that ancient metalworkers apparently used different copper sources to produce the bronze artefacts specific to the region of Luristan in western Iran.