|Quadrangle map, 1:250,000-scale||SK|
|Quadrangle map, 1:63,360-scale||B-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||These placer gold mine workings extend at least 2 miles upstream along McKinley Creek from its junction with Porcupine Creek. Cobb (1972 [MF 424]) included them in his location 26 with other placer gold workings on Porcupine and Cahoon Creeks.|
Gold occurs in modern stream gravels and in older gravels in a high bench deposit on the south side of the valley 200 feet above the modern creek level (Wright, 1904 [B 225 and B 236]). According to Wright , mining of a bench deposit 150 feet above the creek was complicated by a cap of, 'gravel cement 3 feet thick,' that could not be disintegrated with a hydraulic nozzle and was difficult to break with even a hammer and pick.
The following is summarized from Hoekzema and others (1986). McKinley Creek is the largest northwest flowing tributary to Porcupine Creek. It has an average gradient of nearly 500 feet per mile. The Golden Eagle lode gold deposit (SK047) is located adjacent to the creek at an elevation of 1,800 feet approximately 2 miles above its junction with Porcupine Creek. Free gold can be panned from sulfides in the lode deposit. Reconnaissance placer samples collected above the lode deposit contained from less than 0.0004 to 0.0056 ounces gold per cubic yard. Samples from below the lode deposit contained from less than 0.0004 to 0.0539 ounces gold per cubic yard. Placer gold consists of rough, angular fragments. Placer gold from McKinley and Cahoon Creeks ranges from 786 to to 859 fine and averages 821. Gold from two lode gold sources in the area averages 750 fine. Placer gold fineness increases downstream from the probable lode gold source. Pan concentrates contain up to 30% magnetite, 10% pyrite, and minor chalcopyrite, galena, garnet, scheelite, sphalerite, and zircon.The McKinley Creek placer mineralization lies within the northwest trending zone of quartz-sulfide veining in sediments and slates in the Skagway B-4 quadrangle that is described by Wright (1904 [B 225 and B 236]), Eakin (1918 and 1919), and MacKevett and others (1974) and considered to be the source of placer gold in this area.
|Geologic map unit||(-136.231857857649, 59.379669734148)|
|Mineral deposit model||Placer gold deposits that include mineralized modern stream gravels, paleo-stream channels, and bench gravels (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary placer.|
|Workings or exploration||
Hoekzema and others (1986) state that placer mining on lower McKinley Creek (below Cahoon Creek) began at about the same time as on Porcupine Creek (1898) and that most of this section was mined out by 1904. However, Eakin (1918, 1919) states that little mining was conducted on the Porcupine Creek tributaries before 1908 when the Cahoon Creek Gold Mining Co. began work on Cahoon and McKinley Creeks. The stream was diverted into a wooden flume and the creek bed was hydraulically mined.Hoekzema and others (1986) also indicated that from 1903 to 1916 old channels of McKinley Creek up to 200 feet above the current creek level were mined by Cahoon Creek Mining Company. A tunnel dug in 1916 diverted the stream to Porcupine Creek and allowed mining of a plunge pool and the lowermost section of McKinley Creek immediately above Porcupine Creek. Hydraulic booming techniques were reportedly used on upper McKinley Creek above Cahoon Creek in 1926. Suction dredges and hand techniques were used recently in upper McKinley Creek.
|Indication of production||Yes; small|
|Reserve estimates||Hoekzema and others (1986) identified resources 1 mile upstream from the junction with Cahoon Creek that consist of narrow point bar and channel deposits totaling approximately 20,000 cubic yards with from 0.001 to 0.054 ounces of gold per cubic yard. The section below Cahoon Creek has been mined several times and grades of the remaining gravels are unknown.|
|Production notes||A total of at least 79,650 ounces of gold was produced jointly from Porcupine (SK041), Cahoon (SK044), and McKinley Creeks, mostly prior to 1926. Approximately 4,500 ounces of gold were taken from a plunge pool at the base of McKinley Falls located at the junction of McKinley and Porcupine Creeks (Hoekzema and others, 1986) (See Production notes for Porcupine Creek, SK041) Significant production has not been reported from upper McKinley Creek above its junction with Cahoon Creek (Hoekzema and others, 1986).|
Beatty, W.B., 1937, Geology of the placer deposits of Porcupine, Alaska: Seattle, University of Washington, B.Sci. thesis, 97 p.
Berg, H.C., 1984, Regional geologic summary, metallogenesis, and mineral resources of southeastern Alaska: U.S. Geological Survey Open-file Report 84-572, 298 p., 1 plate, scale 1:600,000.
Bundtzen, T.K., 1986, Placer geology of the Porcupine Mining District, Skagway B-4 Quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Public-Data File 86-27, 26 p., 1 sheet, scale 1:40,000.
Bundtzen, T.K., Eakins, G.R., Green, C.B., and Lueck, L.L., 1986, Alaska's mineral industry, 1985: Alaska Division of Geological and Geophysical Surveys Special Report 39, 68 p.
Cobb, E.H., 1972, Metallic mineral resources map of the Skagway quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-424, 1 sheet, scale 1:250,000.
Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mt. Fairweather and Skagway quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-316, 123 p.
Eakin, H.M., 1918, Gold placer mining in the Porcupine district: U.S. Geological Survey Bulletin 662-B, p. 93-100.
Eakin, H.M., 1919, The Porcupine gold placer district, Alaska: U.S. Geological Survey Bulletin 699, 29 p.
Hoekzema, R.B., Fechner, S.A., and Bundtzen, T.K., 1986, Distribution, analysis, and recovery of placer gold from the Porcupine mining area, southeast Alaska: U.S. Bureau of Mines Open-File Report 89-86, 49 p., 4 sheets.
MacKevett, E.M., Jr., Robertson, E.C., and Winkler, G.R., 1974, Geology of the Skagway B-3 and B-4 quadrangles, southern Alaska: U.S. Geological Survey Professional Paper 832, 33 p., 1 plate.
Stewart, B.D., 1926, Notes on placer operations in Porcupine District: Alaska Territorial Department of Mines Miscellaneous Report 109-1, 5 p.
Still, J.C., 1991, Section A: Haines - Klukwan - Porcupine subarea, in U.S. Bureau of Mines, Mineral investigations in the Juneau Mining District, Alaska, 1984-1988: Volume 2 - Detailed mine, prospect, and mineral occurrence descriptions: U.S. Bureau of Mines Special Publication VOL. 2A, 214 p., 9 sheets.
Still, J.C., Hoekzema, R.B., Bundtzen, T.K., Gilbert, W.G., Wier, K.R., Burns, L.E., and Fechner, S.A., 1991, Economic geology of Haines-Klukwan-Porcupine area, southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 91-4, 156 p., 5 sheets, scale 1:63,360.
Still, J.C., Weir, K.R., Gilbert, W.G., and Redman, Earl, 1984, Stream sediment, float, and bedrock sampling in the Porcupine mining area, southeast Alaska: U.S. Bureau of Mines Open-File Report 173-84, 6 p., 1 sheet, scale 1:250,000.
Winkler, G.R., and MacKevett, E.M., Jr., 1970, Analyses of bedrock and stream-sediment samples from the Haines-Porcupine region, southeastern Alaska: U.S. Geological Survey Open-File Report 369, 91 p., 1 sheet, scale 1:125,000.
Wright, C.W., 1904, The Porcupine placer district, Alaska: U.S. Geological Survey Bulletin 236, 35 p.
|Reporters||T.C. Crafford (T. Crafford & Associates, Anchorage)|
|Last report date||2/4/2001|