Hinkley Gulch

Past Producer in Alaska, United States with commodities Gold, Silver, Copper, Tin, Tungsten

Geologic information

Identification information

Deposit ID 10090713
MRDS ID D002677
Record type Site
Current site name Hinkley Gulch

Geographic coordinates

Geographic coordinates: -146.3159, 64.30579 (WGS84)
Relative position Hinkley Gulch is a northwest-trending drainage that flows into Buckeye Creek (BD005). It is located approximately 1.2 miles north of the town of Richardson on the Richardson Highway in the NW1/4SW1/4 section 14, T. 7 S., R. 7 E., of the Fairbanks Meridian. Numerous unimproved roads provide access to the Hinkley Gulch area. It is not labeled on current U.S.G.S. maps. It is locality 12 of Cobb (1972), who summarized relevant references under the name 'Hinkley Gulch'.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Silver Secondary
Copper Secondary
Tin Secondary
Tungsten Secondary

Comments on the commodity information

  • Gangue = Clays (kaolinite)

Materials information

Materials Type of material
Arsenopyrite Ore
Cassiterite Ore
Chalcopyrite Ore
Gold Ore
Pyrite Ore
Pyrrhotite Ore
Scheelite Ore
Feldspar Gangue
Muscovite Gangue
Quartz Gangue
Tourmaline Gangue

Alteration

  • (Local) Hydrothermal alteration of intrusive and/or schist host rocks to clays (kaolinite?).

Mineral occurrence model information

Model code 119
USGS model code 39a
BC deposit profile C01. C02
Deposit model name Placer Au-PGE
Mark3 model number 54

Nearby scientific data

(1) -146.3159, 64.30579

Comments on the geologic information

  • Geologic Description = The Richardson area is characterized by gentle slopes and broad, alluvium-filled valleys (Prindle and Katz, 1913, p. 140). The area is unglaciated and largely overlain by windblown silt, sand, and loess, locally up to 50 meters thick (Foster and others, 1979). The bedrock in the region comprises greenschist to amphibolite facies schist, marble, and gneiss that have been intruded by various igneous bodies (Bundtzen and Reger, 1977, p. 29). The schist and marble are probably Paleozoic, and the gneiss has a probable protolith of Precambrian and Paleozoic sedimentary and igneous rocks (Weber and others, 1978). The intrusive bodies in the area range in composition from rhyolite to andesite. Fine-grained rhyolite containing quartz and feldspar phenocrysts is common throughout the area (Olson and others, 1985). At the nearby Democrat Lode (BD014), the rhyolite contains arsenopyrite, gold, and pyrite, and is albitic, clay, and sericite altered (R.J. Newberry, oral communication, 1998). Structurally, the Richardson region is cut by a northwest-trending fracture system termed the Richardson Lineament. The lineament appears to correspond to the distribution of the rhyolite and other intrusive bodies and placer gold deposits (Bundtzen and Reger, 1977, p. 29). Also, the lineament tends to separate gneissic rocks to the northeast from schistose rocks to the southwest (Swainbank and others, 1984). ? At Hinkley Gulch and in the headwaters of Buckeye Creek (BD005), coarse-grained K-spar, quartz, and muscovite metagranite is in contact with epidote and actinolite hornfels, and a cut also exposes epidote and hornblende gneiss (Bundtzen and Reger, 1977). At Hinkley Gulch, the rocks are hydrothermally altered and intensely fractured. The distinctive rock types are skarn and gneiss. The skarn contains garnet, epidote, and amphibole. The gneiss is white, is altered to kaolinite, and has experienced at least three episodes of quartz veining. Some of the quartz appears as purplish boulders, often associated with tourmaline (Swainbank and others, 1984). This setting is similar to the Campbell-Monroe mine (BD007). It is suspected that Hinkley Gulch and the Campbell-Monroe are situated on the same or similar shear zones (Swainbank and others, 1984). Placer and churn-drill-hole concentrates contain arsenopyrite, biotite, cassiterite, chalcopyrite, epidote, feldspar, garnet, gold, ilmenite, magnetite, muscovite, quartz, pyrite, rutile, scheelite, sphene, tourmaline, and zircon. An assay of a porphyry rock chip sample collected from Hinkley Gulch contained 0.30 ppm Au, 45 ppm Cu, 67 ppm Pb, 52 ppm Zn, 7 ppm Mo, 9 ppm Sb, 21.9 ppm U, and 10.3 ppm Th. The gold fineness in pan concentrates from Hinkley Gulch averaged 670. (Bundtzen and Reger, 1977). Glover (1920?) reported a range in gold fineness of 677 to 680 for Hinkley Gulch.? Placer gold was first discovered in the Richardson district in 1905. Mining initially occurred on the nearby Tenderfoot
  • Geologic Description = Creek (BD039) and extended to Buckeye Creek and associated tributaries. After peak gold production in 1908, mining in the area declined (Olson and others, 1985). There are references to early mining at Hinkley Gulch, but it is unclear when. Mining at Hinkley Gulch has included open-cut and drifting methods (Ellsworth and Parker, 1911). Exploration work is continuing along the Buckeye Creek drainage and Hinkley Gulch. Preliminary work has identified a mineralized fracture trend locally called the Buckeye Zone (F.L. Blystone, written communication, 1998).? From 1905 through 1921, production from the Richardson district was approximately 95,000 ounces of gold and 24,000 ounces of silver (Bundtzen and Reger, 1977). Since 1980, the district has produced approximately 10,000 additional ounces of gold from intermittent mining (Olson and others, 1985). There are references of early mining at Hinkley Gulch, but it is unclear how much Au was produced. Approximately 3,000 ounces of gold was recovered by Terry Anderson from Hinkley Gulch (D. May, oral communication, 1998).

Economic information

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Fairbanks

Comments on the production information

  • Production Notes = From 1905 through 1921, production for the Richardson district was approximately 95,000 ounces of gold and 24,000 ounces of silver (Bundtzen and Reger, 1977). Since 1980, mining from the district has produced an additional 10,000 ounces of gold (Olson and others, 1985). There are references to early mining at Hinkley Gulch, but it is unclear how much Au was produced. Approximately 3,000 ounces of gold was recovered by Terry Anderson from Hinkley Gulch (D. May, oral communication, 1998).

Comments on the workings information

  • Workings / Exploration = Placer gold was first discovered in the Richardson district in 1905. Mining initially occurred on the nearby Tenderfoot Creek and expanded to Buckeye Creek (BD005) and associated tributaries. After peak gold production in 1908, mining in the area declined (Olson and others, 1985). There are references to early mining at Hinkley Gulch, but it is unclear when. Mining at Hinkley Gulch has included open-cut and drifting methods (Ellsworth and Parker, 1911). Exploration work is continuing along the Buckeye Creek drainage and Hinkley Gulch. Preliminary work has identified a mineralized fracture trend locally called the Buckeye Zone (F.L. Blystone, written communication, 1998).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS D002677
USGS Alaska Resource Data File ARDF BD019

Bibliographic references

  • Deposit

    Ellsworth, C.E., and Parker, G.L., 1911, Placer mining in the Yukon-Tanana region: U.S. Geological Survey Bulletin 480, 325 p.

  • Deposit

    Prindle, L.M., and Katz, F.J., 1913, Detailed description of the Fairbanks district, in Prindle, L. M., A geologic reconnaissance of the Fairbanks quadrangle, Alaska: U.S. Geological Survey Bulletin 525, p. 59-152.

  • Deposit

    Saunders, R.H., 1965, A geochemical investigation in the Richardson area, Big Delta quadrangle, Alaska: Alaska Division of Mines and Minerals Geochemical Report 3, 11 p.

  • Deposit

    Bundtzen, T.K., and Reger, R.D., 1977, The Richardson lineament-a structural control for gold deposits in the Richardson mining district, Alaska: Alaska Division of Geological and Geophysical Surveys Geologic Report 55, 46 p.

  • Deposit

    Eberlein, G.D., Chapman, R.M., Foster, H.L., and Gassaway, J.S., 1977, Map and table describing known metalliferous and selected nonmetalliferous mineral deposits in central Alaska: U.S. Geological Survey Open-File Report 77-168-D, 132 p., 1 map, scale 1:1,000,000.

  • Deposit

    Weber, F.R., Foster, H.L., Keith, T.E.C., Dusel-Bacon, C., 1978, Preliminary geologic map of the Big Delta quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-529A, 1 sheet, scale 1:250,000.

  • Deposit

    Menzie, W.D., and Foster, H.L., 1979, Metalliferous and selected nonmetalliferous mineral resource potential in the Big Delta quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-529D, 61 p., 1 sheet, scale 1:250,000.

  • Deposit

    Cobb, E.H., and Eberlein, G.D., 1980, Summaries of data on and lists of references to metallic and selected nonmetallic mineral deposits in the Big Delta and Tanacross quadrangles, Alaska: U.S. Geological Survey Open-File Report 80-1086, 77 p.

  • Deposit

    Swainbank, R.C., Burton, J.P., and Metz, P.A., 1984, Bedrock geology of the Richardson mining district, Alaska: University of Alaska, Mineral Industry Research Laboratory Open-File Report 84-2, 60 p., 8 maps, scale 1:40,000.

  • Deposit

    Olson, B.G., Burton, J., Wolff, E.N., and Swainbank, R.D., 1985, Mining and minerals in the golden heart of Alaska: Fairbanks North Star Borough Publication, 80 p.

  • Deposit

    Chapin, Theodore, 1914, Placer mining in the Yukon-Tanana region: U.S. Geological Survey Bulletin 592-J, p. 357-362.

  • Deposit

    Glover, A.E., 1950, Placer gold fineness: Alaska Territorial Department of Mines Miscellaneous Report 195-1, 38 p.

Comments on the references

  • Primary Reference = Bundtzen and Reger, 1977

General comments

Subject category Comment text
Deposit Model Name = Residual placer and Placer Au (Cox and Singer, 1986; model 39a)

Reporter information

Type Date Name Affiliation Comment
Reporter 26-APR-1999 Cameron S. Rombach Alaska Division of Geological and Geophysical Surveys