Arsenical bronze at Jinsha: Evidence for technological transmission and adaptive alloying in Bronze Age Southwest China

<title>Abstract</title> <p>Arsenical bronze is well documented in northwestern China but remains poorly understood in Southwest China. This study presents the first archaeometallurgical investigation of twelve arsenic-bearing bronze artefacts from the Jinsha site (c. 1600–600 BCE), integrating metallography, elemental composition, and lead isotope analyses. Arsenic contents exceeding 2 wt.% occur in both binary Cu–As and quaternary Cu–Sn–Pb–As alloys, demonstrating intentional alloying rather than the incidental use of arsenic-rich ores. Metallographic evidence indicates that different alloy recipes were selected to achieve distinct technological properties. Lead isotope data reveal diverse metal sources, suggesting flexible metal procurement rather than reliance on a specialized ore supply. These findings provide the first clear evidence for intentional arsenical bronze production at Jinsha, extending the known distribution of this technology in ancient China and indicating its transmission through interregional exchange networks and local adaptation in Southwest China.</p>