Willow Creek

Site Name

Primary: Willow Creek

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Commodity

Primary: Gold
Secondary: Silver
Secondary: Platinum

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Location

State: Alaska
District: Marshall

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Land Status

Not available

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Years of Production:
Organization:
Significant:

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Physiography

Not available

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Mineral Deposit Model

Model Name: Placer Au-PGE

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Orebody

Not available

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Structure

Not available

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Alterations

Not available

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Gold
Ore: Hematite
Ore: Ilmenite
Ore: Magnetite
Ore: Platinum

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Comments

Comment (Geology): Age = Quaternary.

Comment (Geology): Geologic Description = Placer gold was discovered on Willow Creek in 1914. Mining started in 1915, and more than 12,000 ounces were produced in 1916 (Hoare and Cobb, 1977). By the 1950's, placer mining took place along about 2 miles of the drainage from the headwaters of the west fork of Willow Creek near the Arnold lode prospect (RM005) downstream to an elevation of about 200 feet. The deposits were rich. Retherford (1987) estimated that the average grade may have been 0.049 ounce of gold per cubic yard and Brooks (1922) reported that recovery was as much as one-third ounce ($6) of gold per cubic yard. As much as 85,000 ounces of gold may have been produced from Willow Creek by the 1950's (Retherford, 1987). Inasmuch as many of the gravels were coarse and bouldery, much mining included the separate washing of large, angular boulders. Retherford (1987) divided the creek into three segments: (1) the upper canyon is the first mile below the Arnold prospect, where the steep-walled, narrow valley carries 5 to 15 feet of gravel on bedrock; (2) the lower canyon is the next 3,500 feet of the creek, where the flood plain gradually broadens downstream and the alluvial fill is 15 to 35 feet thick; and (3) the next mile downstream is an alluvial fan ('deltaic') complex that has not been mined. The gold was commonly coarse and concentrated on bedrock in the upper canyon. In the middle part of the lower canyon, 15 feet of overburden alluvium with moderate to low gold values covered a thin clay hardpan. Below the hardpan, gold was distributed through 15 feet of a bouldery and clayey pay zone above bedrock (Retherford, 1987). Placer concentrates contained magnetite, ilmenite, hematite, and minor platinum (Harrington, 1918). Retherford (1987) estimated that the potential reserves at Willow Creek include (1) about 480,000 cubic yards of tailings with a grade of 0.008 to 0.012 ounce of gold per cubic yard; and (2) 2,715,000 cubic yards of unmined material in the alluvial fan complex that may have a grade of 0.02 ounce of gold per cubic yard. The low elevation (in part about 150 feet) and proximity to the lower Yukon River lowlands suggests that Quaternary sea-level fluctuations may have influenced the development of the Willow Creek placer deposit.

Comment (Reference): Primary Reference = Retherford, 1987

Comment (Workings): Workings / Exploration = Hand methods, draglines, scrapers, and eventually dozers were used in mining. A ditch was built in 1917 to divert water from Slope Creek to Willow Creek for use in hydraulic mining. A dryland dredge was brought in after WWII and operated for a few years. Many exploration shafts were sunk along the lower part of the creek, nearby tributaries, and along the mountain front both to the east and west of Willow Creek (Retherford, 1987).

Comment (Deposit): Model Name = Placer Au-PGE (Cox and Singer, 1986; model 39a)

Comment (Production): Production Notes = Retherford (1987) estimated that the average grade may have been 0.049 ounce of gold per cubic yard,and Brooks (1922) reported that recovery was as much as one-third ounce ($6) of gold per cubic yard. As much as 85,000 ounces of gold may have been produced from Willow Creek by the 1950s (Retherford, 1987).

Comment (Reserve-Resource): Reserves = Retherford (1987) estimated that the potential reserves at Willow Creek include (1) about 480,000 cubic yards of tailings with a grade of 0.008 to 0.012 ounce of gold per cubic yard, and (2) 2,715,000 cubic yards of unmined material in the alluvial fan complex that may have a grade of 0.02 ounce of gold per cubic yard.

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References

Reference (Deposit): Hoare, J M., and Cobb, E.H., 1972, Metallic mineral resources map of the Russian Mission quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-444, 1 sheet, scale 1:250,000.

Reference (Deposit): Retherford, R.M., 1987, Willow Creek Placer, Marshall District: Calista Corporation, Anchorage, unpublished report, 14 p.

Reference (Deposit): Hoare, J M., and Cobb, E.H., 1972, Metallic mineral resources map of the Russian Mission quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-444, scale 1:250,000.

Reference (Deposit): Harrington, G.L., 1918, The Anvik-Andreafsky region, Alaska (including the Marshall district): U.S. Geological Survey Bulletin 683, 70 p.

Reference (Deposit): Hoare, J.M., and Cobb, E.H., 1977, Mineral occurrences (other than mineral fuels and construction materials) in the Bethel, Goodnews, and Russian Mission quadrangles, Alaska: U.S. Geological Survey Open-File Report 77-156, 98 p.

Reference (Deposit): Brooks, A.H., 1922, The Alaska mining industry in 1920: U.S. Geological Survey Bulletin 722-A, p. 1-74.

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