Stay with the green: New insights into ancient copper smelting in the Tonglüshan site, China

This paper presents new archaeometallurgical analyses from the Tongl & uuml;shan site, a famous ancient mining and smelting site in China. Results show that the primary phases in slag samples from two sites (Sifangtang and Lujia'nao) are all of a vitreous matrix, interspersed with fayalite crystals, w & uuml;stite, and hercynite. The trapped metallic particles in the slag are mainly raw copper with few sulfides present, which indicates a direct reduction process of oxidic ore. Iron-rich minerals were likely to be added as flux implied by the few unreacted inclusions in the slag samples. The extremely low copper content in the slag samples demonstrates a high rate of copper recovery, indicating that the copper smelting technology in the region had reached a considerably advanced level. In the meantime, the variations in metal content in slag samples from different periods reveal the diachronic changes in this copper smelting technology. The Tongl & uuml;shan site, with its millennia of ancient mining and metallurgical activities, provides an excellent material base for detailed studies on technological evolution.