The copper mine at Tonglushan was a large-scale industrial operation from at least the early Spring and Autumn period. Chinese archaeologists have so far excavated 252 vertical shafts going down 150 ft (50 m), with numerous horizontal tunnels leading off to copper working faces.
Both iron and bronze digging tools have been found in the tunnels and at the bottom of the shafts where the miners may have accidentally dropped them while climbing their ladders.
Copper deposits were mined from the bottom upwards: as one tunnel ran out of ore, a new one would be opened further up the vertical shaft. As the ore was pulled to the surface in buckets, waste material from the fresh tunnels could simply be dumped in the lower, worked-out ones, rather than having to be hauled to the surface.
Tunnels were lit by two pieces of flaming bamboo stuck to the walls. Air flow was directed down to the miners by manipulating the opening of different shaft mouths.
