Brief Geology And Mining History

From:  Mindat.org

   Coffee Creek crosses the Nome-Taylor road at about mile 74 and again at almost mile 75. Placer mining took place for about 8,500 feet downstream from the Nome-Taylor road crossing at about mile 75. Coffee Creek merges with Quartz Creek to become Whelan Creek 10,000 feet downstream from the lower mine workings. Small tributaries to the mined section of Coffee Creek, including Dome Creek and Wonder Gulch (BN005), were mined adjacent to Coffee Creek and are included as part of this locality. Coffee Creek is location 45 of Cobb (1972; MF 417).
Geology: Up to 25 feet of muck covered, gold-bearing stream gravels were initially mined in 1901 here (Collier, 1902). The lower part of the mined drainage is cut into alluvial terrace gravels, the Kougarok gravel, (Hopkins, 1963) but most of the mined drainage is on low grade Lower Paleozoic metasedimentary bedrock (Till and others, 1986). Kougarok gravel carries small amounts of gold (Sainsbury and others, 1969; Sainsbury, 1975) but at least part of the gold in Coffee Creek appears to be derived from local bedrock sources. A residual placer contains angular, spongy, and bright gold in 4 to 7 feet of angular schist and quartz and adjacent weathered schist bedrock (Collier and others, 1908) in the headwaters of Wonder Gulch (BN005). Small amounts of cinnabar are present in placer concentrate from Coffee Creek and Wonder Gulch; cerussite and pyromorphite are also present in concentrate from Wonder Gulch (Anderson, 1947).
Workings: Various combinations of hand, scraper, dozer, dragline, and sluice surface operations have taken place along 8,500 feet of the Coffee Creek drainage and the adjacent 1,000 feet of Dome Creek, and 1,500 feet of Wonder Gulch (Sainsbury and others, 1969). Early mining included winter underground drifting and summer sluicing (Cobb, 1975).
Age: Quaternary

   The upper part of Coffee Creek that has been placer mined is 5,000 feet upstream from the road crossing at mile 74. About 1,500 feet of the drainage was open-cut mined at this location (Sainsbury and others, 1969). This is locality 43 of Cobb (1972; MF 417).
Geology: This small area of placer workings is primarily known from the mapping of Sainsbury and others (1969). Early references to a residual gold placer near the head of Coffee Creek (Collier and others, 1908; Cobb, 1975, OFR 75-429) are for the Wonder Gulch tributary (BN005) and not this location. Thick muck deposits are present on Coffee Creek and bedrock is not exposed in this area. Bedrock here is expected to be low grade, Lower Paleozoic metasedimentary rocks like those exposed on lower parts of Coffee Creek and nearby uplands (Till and others, 1986).
Workings: Open-cut placer mining, probably dozer and sluice operations, took place along 1,500 feet of the active drainage.

Commodities (Major) - Au
Development Status: Yes; small
Deposit Model: Placer Au-PGE (Cox and Singer; model 39a)

References:
Anderson, Eskil, 1947, Mineral occurrences other than gold deposits in northwestern Alaska: Alaska Territorial Division of Mines Pamphlet 5-R, 48 p. Cobb, E.H., 1972, Metallic mineral resources map of the Bendeleben quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-417, 1 sheet, scale 1:250,000. Cobb, E.H., 1975, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Bendeleben quadrangle, Alaska: U.S. Geological Survey Open-File Report 75-429, 123 p. Collier, A.J., 1902, A reconnaissance of the northwestern portion of Seward Peninsula, Alaska: U.S. Geological Survey Professional Paper 2, 70 p. Collier, A.J., Hess, F.L., Smith, P.S., and Brooks, A.H., 1908, The gold placers of parts of Seward Peninsula, Alaska, including the Nome, Council, Kougarok, Port Clarence, and Goodhope precincts: U.S. Geological Survey Bulletin 328, 343 p. Hopkins, D.M., 1963, Geology of the Imuruk Lake area, Seward Peninsula, Alaska: U.S. Geological Survey Bulletin 1141-C, p. C1-C101. Sainsbury, C.L., Kachadoorian, Reuben, Hudson, Travis, Smith, T.E., Richards, T.R., and Todd, W.E., 1969, Reconnaissance geologic maps and sample data, Teller A-1, A-2, A-3, B-1, B-2, B-3, C-1, and Bendeleben A-6, B-6, C-6, D-5, and D-6 quadrangles. Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 377, 49 p., 12 sheets, scale 1:63,360. Till, A.B., Dumoulin, J.A., Gamble, B. ., Kaufman, D.S., and Carroll, P.I., 1986, Preliminary geologic map and fossil data, Soloman, Bendeleben, and southern Kotzebue quadrangles, Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 86-276, 10 p., 3 plates, scale 1:250,000.

Past production and other historical records.