The authors conducted a comprehensive analysis of 13 bronze coins excavated from the Eastern Zhou capital site of Luoyi (洛邑), employing metallographic microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) for compositional analysis, and multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) for lead isotope ratio determination. The results reveal that the Eastern Zhou bronze coins from Luoyang were primarily made of two alloy types: pure copper and lead-tin bronze. The spade-shaped kongshoubu coins exhibited stable alloy ratios and casting techniques, while the round coins were cast from pure copper. The coins utilized two distinct lead sources: common lead and highly radiogenic lead. Notably, the widespread presence of highly radiogenic lead in Eastern Zhou bronzeware warrants further investigation. A remarkable discovery was a flat-shaped pingshoubu coin with an exceptionally high 206Pb/204Pb ratio of 30.44, indicating uranium-derived lead, a geologically rare signature. Comparative analysis with published ore data suggests that the Zhongtiaoshan (中条山) copper mine, particularly the Tongkuangyu deposit, as a likely source, providing direct evidence for the exploitation of metal resources from this region during the Eastern Zhou period. Metallographic examination revealed abundant copper sulfide inclusions, indicating the use of sulfide copper ores in smelting. This study integrates metallurgical history research with archaeology, providing new evidence for exploring the sources of copper-casting metal resources in the Luoyi region during the Eastern Zhou Dynasty, and provides fresh perspectives for research on royal and regional bronze production and culture. Additionally, it contributes to refining the archaeological cultural sequence of the ancient copper mining activities in the Zhongtiaoshan region. The findings also guide future archaeological investigations of ancient mining sites in Zhongtiaoshan.
Xiaohong YUAN (Mon,) studied this question.