Origin of iron production in the Eastern Mediterranean: Osmium isotope and highly siderophile element evidence from Iron Age Jordan

Abstract

Osmium isotope and highly siderophile element (HSE: Os, Ir, Ru, Rh, Pt, Pd, Re, Au) abundance analysis provides a new methodology for examining the origins of ancient iron production in the Eastern Mediterranean, a current scholarly lacuna. Here we present results from a two-stage campaign of laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) followed by thermal ionization mass spectrometry and solution ICP-MS to measure mixed iron-copper chunks and iron objects from the Faynan region of Jordan. Faynan is a copper-ore resource zone with a rich history of copper smelting. The combination of sophisticated copper metallurgy and iron artifacts in the archaeological record of Iron Age Faynan (10th-9th centuries BCE) offers an exceptional opportunity to investigate the hypothesis that iron production originally developed as an adventitious byproduct of advanced copper smelting technologies. Based on the results, we find no connection from HSE abundances and inter-element ratios, or osmium isotopes, between the iron objects (Pt/Os = 2–7; 187Os/188Os = 1.15 to 2.50) and mixed metal chunks from the furnaces (Pt/Os = 7.7–35; 187Os/188Os = 2.15 to 8.96) excavated in Faynan, indicating that the objects were not locally produced. This conclusion provides additional evidence that iron production in the Levant was probably not directly developed from copper smelting. In turn, osmium isotopes and siderophile element abundances in artifacts and products from metal production can also offer a new line of evidence for examining exchange networks in the Iron Age Eastern Mediterranean and elsewhere.