John Treadwell was a contractor, not a miner. When he inspected a low-grade gold deposit on Douglas Island in 1881 and was asked his opinion, he said it was worthless. Then he bought it. Treadwell understood something other investors missed: extremely low-grade ore could be profitable if you processed enormous volumes of it cheaply — and the combination of cheap waterpower, deep harbor access, and abundant timber made Douglas Island ideal for massive stamp mill operations.
The Treadwell Complex eventually comprised four separate mines — the Treadwell, the 700 Foot, the Mexican, and the Ready Bullion — operating under one corporate umbrella. Together their stamp mills represented the single largest gold milling operation in the world. Thousands of stamps pounding ore 24 hours a day produced a rhythmic thudding audible throughout Juneau across the Gastineau Channel.
The mines ran directly beneath the tidal flats of Gastineau Channel. As the underground workings expanded and the pillars supporting the ceiling were removed to extract their ore, the ground above slowly subsided. On April 21, 1917, the ocean broke through. Miners heard a rumbling and most escaped through emergency exits. Within hours, seawater had permanently flooded hundreds of miles of tunnels. The operation that had made Alaska's capital city was gone overnight.
The same geological system that produced Treadwell extends along the Juneau Gold Belt — a zone of gold-bearing quartz veins running along the west face of the Coast Range. The Alaska-Juneau Mine (AJ Mine) on the Juneau mainland operated until 1944. Modern exploration companies have repeatedly evaluated a potential reopening of the AJ Mine deposits, which contain millions of ounces at low grades amenable to large-scale processing.
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