Archaeometallurgical Study of Copper-Based Objects from Achaemenid Persepolis

Abstract

Metallurgical production during the Achaemenid era reflects a high level of technical knowledge and artistic craftsmanship in the ancient Near East. However, the material composition and production techniques of copper-alloy objects from this period have not been fully investigated. This study analyzes fourteen copper-based artefacts discovered during early archaeological excavations at the Persepolis World Heritage Site. The assemblage includes ten arrowheads, two broken pin fragments, thin metal strips interpreted as parts of bracelets, and a rod fragment. To identify their chemical composition and manufacturing processes, the objects were examined using inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDS), and metallographic observation. The analysis shows that most of the artefacts were made from tin bronze and lead-containing tin bronze, while the bracelet element was produced from brass. The technological evidence indicates that the arrowheads were mainly cast, although some were further treated through annealing. In contrast, the pins, bracelet piece, and rod were formed through repeated cycles of cold hammering and annealing. The deliberate selection of leaded tin bronze for cast utilitarian objects and brass for thin decorative components demonstrates advanced knowledge of alloy behavior and metalworking techniques. Overall, the findings enrich our understanding of Achaemenid metallurgical traditions, production skills, and craft organization at Persepolis.