Poorman Creek

Site Name

Primary: Poorman Creek
Secondary: Kast
Secondary: Nelson and Larson

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Commodity

Primary: Gold
Secondary: Zirconium
Secondary: Uranium
Secondary: Thorium
Secondary: Tin
Secondary: Platinum
Secondary: Copper

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Location

State: Alaska
District: Yentna

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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: Iridosmine
Ore: Ilmenite
Ore: Iridium
Ore: Magnetite
Ore: Platinum
Ore: Pyrite
Ore: Cassiterite
Ore: Gold

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Comments

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

Comment (Deposit): Other Comments = This placer ground is shown by C.C. Hawley and Associates, Inc. (1978) as part of the reserve area held by the Peters Creek Mining Corporation. See also Peters Creek (TL045).

Comment (Geology): Geologic Description = Poorman Creek drains across the contact between Mesozoic slate and argillite (KJs) cut by Tertiary (?) soda rhyolites with associated quartz stringers and continentally derived Tertiary sedimentary rocks of the Kenai Group (Mertie, 1919; Reed and Nelson, 1980). The discovery claim is underlain by Mesozoic sedimentary rocks that strike N35E and dip 55NW (Mertie, 1919; Robinson and others, 1955; Reed and others, 1978).? Mining on Poorman Creek began at least as early as 1907 when six men recovered 1,329 ounces of gold (Garrett, 1998). Mertie (1919) reported that a bench deposit near the mouth of Dandy Creek, covered 2500 square feet and averaged 25 feet thick, or about 2300 cubic yards of gravel. ? Concentrates contain cassiterite, gold, ilmenite, iridium, iridoosmium, magnetite, platinum, pyrite, garnet, quartz, and zircon (Cobb and Reed, 1980). Grades of 0.09% U, 0.06% ThO2, 0.229% eU, and 0.22% Cu are reported from the concentrates (Mertie, 1919). The U.S. Geological Survey analyzed a sample of platinum metals weighing 41.6 grains, with specific gravity of 18.1, which contained 32% iridoosmium, 11% iridium, 1.4% rhodium, 47.3% platinum, trace palladium, and 8.3% other elements. Concentrates were reported to run 36.54% tin, equivalent to 46% cassiterite (Mertie, 1919; Robinson and others, 1955). According to Mertie (1919), gold and cassiterite were likely to have been derived from mineralized bedrock within the drainage. He also reported that Poorman Creek contained the most platinum of any placer in the Kahiltna valley. Clark and Hawley (1968) indicate that platinum-group minerals in the Yentna District may be derived from altered mafic or ultramafic dikes that cut the Mesozoic sedimentary rocks.? Also see Peters Creek (TL045).

Comment (Reference): Primary Reference = Mertie, 1919

Comment (Workings): Workings / Exploration = Garrett (1998) reports current placer mining by mechanical cut-and-fill techniques and feed hopper, trommel and sluice processing. Garrett (1998) reports current placer mining by mechanical cut-and-fill techniques and feed hopper, trommel and sluice processing. Exploration has been conducted by test drilling and pits. Hydraulic and hand-mining operations were conducted in the past.

Comment (Geology): Age = Pleistocene.

Comment (Production): Production Notes = A bench deposit near the mouth of Dandy Creek mined in 1917 (Mertie, 1919) covered 2500 square feet and averaged 25 feet thick, or about 2300 cubic yards of gravel. Concentrate contained 0.09% U, 0.06% ThO2, 0.229% Eu, and 0.22% Cu. The U.S. Geological Survey analyzed a sample of platinum metals weighing 41.6 grains, with specific gravity of 18.1, which contained 32% iridosmium, 11% iridium, 1.4% rhodium, 47.3% platinum, trace palladium, and 8.3% other elements. Concentrates were reported to run 36.54% tin, equivalent to 46% cassiterite (Mertie, 1919; Robinson and others, 1955).

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References

Reference (Deposit): Smith, P.S., 1930, Mineral industry of Alaska in 1927: U.S. Geological Survey Bulletin 810-A, p. 1-64.

Reference (Deposit): Smith, P.S., 1941, Mineral industry of Alaska in 1939: U.S. Geological Survey Bulletin 926-A, p. 1-106.

Reference (Deposit): Smith, P.S., 1933, Mineral industry of Alaska in 1930: U.S. Geological Survey Bulletin 836-A, p. 1-83.

Reference (Deposit): Smith, P.S., 1930, Mineral industry of Alaska in 1928: U.S. Geological Survey Bulletin 813-A, p. 1-72.

Reference (Deposit): Mertie, J.B., Jr., 1919, Platinum-bearing gold placers of the Kahiltna Valley: U.S. Geological Survey Bulletin 692-D, p. 233-264.

Reference (Deposit): Clark, A.L., and Cobb, E.H., 1972, Metallic mineral resources map of the Talkeetna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-369, 1 sheet, scale 1:250,000.

Reference (Deposit): Paige, Sidney, and Knopf, Adolph, 1907, Reconnaissance in the Matanuska and Talkeetna basins, Alaska, with notes on the placers of the adjacent regions: U.S. Geological Survey Bulletin 314-F, p. 104-125.

Reference (Deposit): Capps, S.R., 1924, Geology and mineral resources of the region traversed by the Alaska Railroad: U.S. Geological Survey Bulletin 755-C, p. 73-150.

Reference (Deposit): Capps, S.R., 1913, The Yentna district, Alaska: U.S. Geological Survey Bulletin 534, 75 p.

Reference (Deposit): Brooks, A.H., 1908, The mining industry in 1907: U.S. Geological Survey Bulletin 345, 294 p.

Reference (Deposit): Brooks, A.H., 1921, The future of Alaska mining, in Martin G.C. and others, Mineral resources of Alaska, 1917: U.S. Geological Survey Bulletin 714, p. 5-57.

Reference (Deposit): Brooks, A.H., 1914, Mineral resources of Alaska in 1913: U.S. Geological Survey Bulletin 592, p. 340-341.

Reference (Deposit): U.S. Bureau of Mines, 1998, Minerals Availability System/Minerals Industry Location System (MAS/MILS), Talkeetna Quadrangle: Worldwide Web URL http://imcg.wr.usgs.gov/data.html.
URL: http://imcg.wr.usgs.gov/data.html

Reference (Deposit): Garrett, D. R., 1998, The Blue Ribbon Mine, Yentna Mining District, Alaska: Worldwide Web URL http://www.alaska.net/~freegold/brm.html.
URL: http://www.alaska.net/~freegold/brm.html

Reference (Deposit): Robinson, G. D., Wedow, Helmuth, Jr., and Lyon, J. B., 1955, Radioactivity investigations in the Cache Creek area, Yentna district, Alaska 1945: U.S. Geological Survey Bulletin 1024-A, p. 1-23.

Reference (Deposit): Smith, P.S., 1933, Mineral industry of Alaska in 1930: U.S. Geological Survey Bulletin 836, p. 1-83.

Reference (Deposit): Smith, P.S., 1939, Mineral industry of Alaska in 1938: U.S. Geological Survey Bulletin 917-A, p. 1-113.

Reference (Deposit): Smith, P.S., 1930, Mineral industry of Alaska in 1928: U.S. Geological Survey Bulletin 813, p. 1-72.

Reference (Deposit): Smith, P.S., 1932, Mineral industry of Alaska in 1929, in Smith, P.S., and others Mineral resources of Alaska, report on progress of investigations in 1929: U.S. Geological Survey Bulletin 824-A, p. 1-81.

Reference (Deposit): Reed, B.L., Nelson, S.W., Curtin, G.C., and Singer, D.A., 1978, Mineral resources map of the Talkeetna Quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-870-D, 1 sheet, scale 1:250,000.

Reference (Deposit): Cobb, E.H., and Reed, B.L., 1980, Summaries of data and lists of reference to metallic and selected nonmetallic mineral deposits in the Talkeetna quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-884, 106 p.

Reference (Deposit): Reed, B.L., and Nelson, S.W., 1980, Geologic map of the Talkeetna quadrangle: U.S. Geological Survey Miscellaneous Investigations Map I-1174, scale 1:250,000.

Reference (Deposit): C.C. Hawley and Associates, Inc., 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska: U.S. Bureau of Mines Open-File Report 24-78, 275 p., 7 plates.

Reference (Deposit): Cobb, E.H., 1973, Placer deposits of Alaska: U.S. Geological Survey Bulletin 1374, 213 p.

Reference (Deposit): MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.

Reference (Deposit): Clark, A.L., and Hawley, C.C., 1968, Reconnaissance geology, mineral occurrences, and geochemical anomalies of the Yentna district, Alaska: U.S. Geological Survey Open-File Report 68-35, 64 p.

Reference (Deposit): Mertie, J.B., Jr., 1969, Economic geology of platinum minerals: U.S. Geological Survey Professional Paper 630, 120 p.

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