At the Tonglushan Site Museum, visitors can view a vast archaeological excavation resembling an "underground labyrinth". The original mining site, a dense network of shafts and tunnels, has been preserved in situ beneath a protective exhibition hall measuring 36 meters long and 30 meters wide, built in 1984.
Viewed from above, visitors see a "maze" of vertical shafts, inclined passageways, horizontal tunnels, and blind shafts supported by wooden structures.
Drainage channels and wooden troughs weave through the complex, offering a vivid picture of how ancient miners excavated ore and maintained underground operations.
The museum's new building, opened in June 2023, features five themed exhibition halls that explore how ancient people located copper deposits, developed mining techniques, mastered smelting technology, and transported bronze materials across the region.
Wu says that in ancient times, people often located copper deposits by looking for a plant called Elsholtzia splendens, which has red stems and green leaves. It resembles a toothbrush and produces purple flowers.
Every November, when the flowers are in full bloom, Tonglushan Mountain is covered in a sea of purple.
The site's copper-smelting technology was remarkably advanced. Ancient metallurgists developed a stone-built shaft furnace into which alternating layers of ore and charcoal were loaded. Unlike contemporary furnaces in Mesopotamia, which were typically used only once, these furnaces could be reused repeatedly.
It is estimated that the mining area produced about 400,000 metric tons of ancient slag, yielding between 80,000 and 120,000 tons of crude copper. The copper ingots smelted had a copper content of over 93 percent, while the slag contained only 0.7 percent copper — evidence of highly efficient purification techniques.
"This level is remarkably close to modern standards," Wu says.
Scientific testing has since confirmed that the elemental composition of copper used in bronze artifacts from the Panlongcheng site in Wuhan, Hubei province, and the bronzes found in Fu Hao's tomb at Yinxu matches that of copper from Tonglushan.
The findings provide strong evidence that Tonglushan served as a major source of copper for China's bronze industry in ancient times,"proving that China's bronze civilization developed independently and formed its own system", Wu says.
Daye, where the Tonglushan site is located, is adjacent to the Yangtze River. At that time, the transportation route likely involved moving goods via the Yangtze River to an ancient dock in Nanyang, Henan, and finally reaching the ancient capital Luoyang, then a major political and cultural center.
"The abundant copper resources in the middle reaches of the Yangtze River, combined with bronze smelting and casting technologies that spread southward from the Central Plains dynasties in northern China, together created the bronze civilization of the Yangtze River basin," says Zhang Changping, a history professor from Wuhan University.
