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The Treadwell gold mine was on the south side of Douglas Island, .5-mile (0.80 km) east of downtown Douglas and southeast of downtown Juneau, owned and operated by John Treadwell. Composed of four sub-sites, Treadwell was in its time the largest hard rock gold mine in the world, employing over 2,000 people. Between 1881 and 1922, over 3 million troy ounces of gold were extracted. Not much remains today except for a few crumbling buildings and a "glory hole". Although John Treadwell had twelve years of experience in both placer and lode mines, he was a carpenter and builder by trade who had come to Alaska prior to the Klondike Gold Rush.
In 1880, prospectors Joseph 'Joe' Juneau and Richard Harris discovered gold in Silver Bow Basin. This brought waves of prospectors to the region, including John Treadwell, whose first move was to purchase a lode claim on Douglas Island from Pierre Joseph Erussard de Ville. Treadwell also formed a partnership in September, 1881 with Erussard de Ville, D.P. Mitchell and Dave Martin under the name of The San Francisco Company. For unknown reasons he later backed out of this, and in early December 1881 he devoted his attention solely to the Douglas Island property. He then went on to buy two claims neighboring his property from D. W. Clark. Treadwell extracted twenty two samples from his three claims which he sent to San Francisco, California for a mill test, yielding encouraging results.
On December 27, 1881, Treadwell organized the Alaska Mill & Mining Company and began operations at the Treadwell Dike. Shortly after this, five men from California bought over $10,000 worth of stock in the business. These men were James Freeborn ( 1828 - June 21, 1894 ), San Francisco banker and mining magnate John Douglas Fry (July 1, 1819 - February 3, 1901 ), Horace Lewis Hill (1840 - November 6, 1912 ), Howard Hill Shinn ( born April 4, 1857 ) and E. M. With these men funding him, Treadwell began running a tunnel and discovered that much of the vein he was mining was not on his property. Because word of his strike had not yet gotten out he was able to buy many of the adjoining claims for very little money, after which he returned to San Francisco to secure more backing for a much larger mill. His financial benefactors agreed to invest more and the major mining operation had begun.
In 1889, Treadwell sold his stake in the company for $1.5 million and returned to California.
At the height of the operation there were five mills with over 960 stamps in continuous operation, closing down only on Christmas and Independence Day. These mills were fed by four mines known as the Treadwell, 700-Foot, Mexican and Ready Bullion. At this time the mine employed over 2,000 people and was the largest hard rock mine in the world. The gold was 55% free milling and 45% embedded in pyrite, which was extracted using chlorination, smelting, and cyanidation. Power to the complex was supplied by a coal-fired power plant (later switching to oil and two hydroelectric dams).
Some of the shafts extended as much as 2,400 feet (730 m) below the surface.
The mine was still yielding gold in 1917 when the Treadwell, 700-Foot and Mexican mines (excavated to a depth of more than 500 feet (150 m) below sea level under Gastineau Channel) suddenly began leaking and were evacuated. Hours later the mines collapsed. At the climax, sprays of water were sent up to 200 feet (61 m) in the air from the mine entrances. The only casualties were a dozen horses and one mule; local lore has it that one man unaccounted for used the opportunity to head for parts unknown.
Evidence of instability had been noticed around 1909, but there was no indication of impending disaster until 1913, when major geological shifts occurred. Reinforcements were constructed but were ineffective. The last shaft was worked in a limited fashion until 1922.
The site eventually became the property of Alaska Electric Light & Power, which has since deeded a portion to the city of Juneau with the stipulation that it be maintained as a historic site. Under the management of the Treadwell Historic Preservation & Restoration Society there are recreation trails with markers identifying various locations. Another portion of the property is leased to a zip line operator.
Directly above the cave-in site is a concrete pad where the Alaska Department of Transportation and Public Facilities places a 105mm howitzer, which is fired across Gastineau Channel at a shoulder of Mount Roberts to break up avalanches before they get so big as to pose a danger to Thane Road and residences there.
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