| Willow Creek mining district | |
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| — Alaska Mining District — | |
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Willow Creek mining district
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The Willow Creek mining district, also known as the Independence Mine/Hatcher Pass district, is a gold-mining area in the U.S. state of Alaska. Underground hard-rock mining of gold from quartz veins accounts for most of the mineral wealth extracted from the Hatcher Pass area. The first mining efforts were placer mining of stream gravels, and placer mining in the area has continued sporadically to this day. Robert Hatcher discovered gold and staked the first claim in the Willow Creek valley in September 1906. The first lode mill in the area started operating in 1908. Underground mining continued at a variety of locations around the pass until 1951. In the 1980s one of the area's hard-rock mines was briefly re-opened. At least one mining company is actively exploring for gold in the area now.[1] Through 2006 the district produced 667-thousand ounces of hard rock gold and 60-thousand ounces of placer gold.[2]
The lode gold mines at Hatcher Pass exploit gold-bearing quartz (+/- Ag, W, Sb, As, Cu, Mo, Pb, Te, Zn, Hg) veins in a variety of granitic intrusive rocks and country-rock schist. Near the pass, the southwestern margin of the Tertiary-Cretaceous-age Talkeetna Mountains batholith abuts an older pelitic schist unit. The Talkeetna Mountains batholith in this area consists of a 74ma-old tonalite body to the east and a 67ma-old quartz monzonite to the west. The schist consists mainly of metamorphosed and deformed sedimentary rocks, probably of Jurassic age. Plutonic bodies and dikes of Jurassic age are found within the schist, some are deformed, some postdate deformation. Undeformed Tertiary terrastial sediments of the Chickaloon and Arkose Ridge Formations lie to the south of the Jurassic schists and intrusives.[3] Gold deposits occur in the 74ma-old tonalite, the enclosing schist, and the Jurassic intrusives, but not in the 67ma-old quartz monzonite or in the Tertiary sediments.[4]
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What is now called Independence Mine was once two mines: The Alaska Free Gold Mine on Skyscraper Mountain, and Independence Mine on Granite Mountain. In 1938 the two were brought together under one company, the Alaska-Pacific Consolidated Mining Company (APC). With a block of 83 mining claims, APC became the largest producer in the Willow Creek Mining District. The claims covered more than 1,350 acres (5.5 km2) and included 27 structures. In its peak year, 1941, APC employed 204 men, blasted nearly a dozen miles of tunnels, and produced about 35,000 ounces of gold.
In 1942, the War Production Board designated gold mining as nonessential to the war effort. Gold mining throughout the United States came to a halt, but Independence Mine was permitted to continue to operate because of the presence of scheelite, an ore of the "strategic mineral" tungsten, which occurs in the quartz lode with the gold. In 1943, Independence Mine was ordered to close. Mining interests returned to Hatchers Pass when gold prices rose in the mid-1970s; this resulted in a short period of production from the Independence Mine in 1982 by Coronado Mining Company.[5]
Today, Independence Mine is a part of the Independence Mine State Historical Park, a popular winter recreation area. Displays of mining artifacts may also be viewed at the Dorothy Page Museum and Old Wasilla Townsite in downtown Wasilla, Alaska.
The Independence was the largest mine in the Willow Creek District, over a dozen other hard rock mines operated, and may operate again, within a few miles.
The Willow Creek Mines includes the Lucky Shot mine (Gold, copper, lead, zinc, arsenic) and War Baby mine (Gold, copper) veins, which produced from veins cutting the igneous country rock. Combined production for the two mines between 1919 and 1940 was about 252,000 ounces of gold, with some copper. Grade was about 2.2 ounces of gold per ton.
The Gold Bullion Mine (Gold, copper, mercury), produced about 77,000 ounces of gold, at a grade of 1.7 ounces per ton, from quartz veins in igneous rock.
The Fern Mine (Gold, lead, tungsten, tellurium), produced about 44,000 ounces of gold between 1922 and 1950 from quartz veins in shears in igneous rock.
The Martin Mine (Gold, copper, lead), produced about 28,000 ounces of gold from two veins between 1911 and 1920, at an average grade of 1 ounce per ton.
The Gold Cord Mine (Gold, copper, lead, zinc, tungsten), produced about 16,000 ounces of gold, mainly between 1931 and 1938, from veins with grades ranging for 0.1 to 9 ounces per ton.