|Quadrangle map, 1:250,000-scale||SR|
|Quadrangle map, 1:63,360-scale||A-3|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This mine is located in the SW1/4 section 9, T. 2 S., R. 9 E., of the Seward Meridian. It is about 0.5 mile southeast of Horseshoe Bay at an elevation of 125 feet. This is location 259 of Cobb and Tysdal (1980) and location S-3 of Jansons and others (1984). This location is accurate to within 300 feet.|
The deposit at the Duke mine consists of massive sulfide lenses in northeast-striking, interbedded slate and graywacke of the Orca Group of early Tertiary age (Kurtak and Jeske, 1986). The lenses vary from 4 to 27 feet wide and have a strike length of as much as 151 feet. The deposit occurs on the northwest limb of a shallowly northeast-plunging antiform (Stejer, 1956). The sulfide minerals are mostly pyrite with minor amounts of chalcopyrite and pyrrhotite (Stejer, 1956). The typical mineralization consists of a disseminated halo of pyrite surrounding massive pyrite with some chalcopyrite (Stejer, 1956). The footwall of the massive sulfide lenses is in many places a slate bed, and the highest grade of copper mineralization is under the footwall (Kurtak and Jeske, 1986).Within or near the massive sulfide lenses, the country rock shows varied degrees of silicification, sericitization, and kaolinization (Stejer, 1956). Some faulting occurs that is generally parallel to bedding. Surface outcrops located about 100 feet from the shaft indicate that the mineralized belt has a width of 200 to 250 feet. It appears to be on the same trend as the Duchess (SR302) mineralized zone, which lies 2,400 feet north of this deposit (Kurtak and Jeske, 1986).
|Geologic map unit||(-147.926415186677, 60.0142473065429)|
|Mineral deposit model||Besshi massive sulfide (Cox and Singer, 1986; model 24b)|
|Mineral deposit model number||24b|
|Age of mineralization||Tertiary or younger; the mineralization is in rocks of the Orca Group of Tertiary age.|
|Alteration of deposit||There is strong asymmetric sericite-chlorite alteration associated with the massive sulfide mineralization (Rogers and Hoyt, 1999).|
|Workings or exploration||The initial claims were staked in 1898, and by 1907, a two-compartment shaft had been sunk on the property. In 1908, the shaft was deepened to 110 feet, but the site abandoned when the shaft flooded. In 1918, the shaft was pumped out, and a total of 311 feet of crosscuts and drifts was completed. The property was abandoned until 1970, when Northwest Exploration drilled several core holes (Kurtak and Jeske, 1986).|
|Indication of production||Yes; small|
|Reserve estimates||There are measured reserves of 68,800 tons of ore containing 1.32 percent copper, 0.06 ounce of gold per ton, and 0.05 ounce of silver per ton (Kurtak and Jeske, 1986). Indicated reserves are 200,000 tons of ore containing 1.32percent copper, 0.06 ounce of gold per ton and 0.06 ounce of silver per ton (Rogers and Hoyt, 1999).|
|Production notes||An unspecified amount, believed to be small, of production was reported in 1907 (Kurtak and Jeske, 1986).|
Additional commentsThis mine is known as the Reynolds-Alaska Development Co. in Cobb and Tysdal (1980 [MF-880-A]).
Berg, H.C., and Cobb, E.H., 1967, Metalliferous lode deposits of Alaska: U.S. Geological Survey Bulletin 1246, 254 p.
Brooks, A.H., 1912, The mining industry in 1911, in Brooks, A.H., and others, Mineral resources of Alaska, report on progress of investigations in 1911: U.S. Geological Survey Bulletin 520-A, p. 17-44.
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-A, p. 5-57.
Cobb, E.H., and Richter, D.H., 1972, Metallic mineral resources map of the Seward quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-466, 2 sheets, scale 1:250,000.
Cobb, E.H., and Tysdal, R.G., 1980, Summaries of data on and list of references to metallic and selected nonmetallic mineral deposits in the Blying Sound and Seward quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-621, 276 p.
Condon, W.H., and Cass, J.T., 1958, Map of a part of the Prince William Sound area, Alaska, showing linear geologic features as shown on aerial photographs: U.S. Geological Survey Miscellaneous Investigations Series Map I-273, 1 sheet, scale 1:125,000.
Grant, U.S., 1906, Copper and other mineral resources of Prince William Sound: U.S. Geological Survey Bulletin 284, p. 78-87.
Grant, U.S., and Higgins, D.F., Jr., 1909, Notes on geology and mineral prospects in the vicinity of Seward, Kenai Peninsula: U.S. Geological Survey Bulletin 379-C, p. 98-107.
Grant, U.S., and Higgins, D.F., Jr., 1910, Reconnaissance of the geology and mineral resources of Prince William Sound, Alaska: U.S. Geological Survey Bulletin 443, 89 p.
Jansons, Uldis, Hoekzema, R.B., Kurtak, J.M., and Fechner, S.A., 1984, Mineral occurrences in the Chugach National Forest, southcentral Alaska: U.S. Bureau of Mines Mineral Land Assessment 5-84, 218 p., 2 sheets, scale 1:250,000.
Johnson, B.L., 1918, Mining on Prince William Sound: U.S. Geological Survey Bulletin 662-C, p. 183-192.
Kurtak, J.M., and Jeske, R.E., 1986, Mineral investigations in the Chugach National Forest, Alaska (Islands area): U.S. Bureau of Mines Open-File Report 54-86, 302 p., 1 sheet, scale 1:63,360.
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.
Moffit, F.H., 1908, Notes on copper prospects of Prince William Sound: U.S. Geological Survey Bulletin 345-C, p. 176-178.
Moffit, F.H., 1954, Geology of the Prince William Sound region, Alaska: U.S. Geological Survey Bulletin 989-E, p. 225-310.
Moffit, F.H., and Fellows, R.E., 1950, Coper deposits of the Prince William Sound district, Alaska: U.S. Geological Survey Bulletin 963-B, p. 47-80.
Nelson, S.W., Dumoulin, J. A., and Miller, M.L., 1985, Geologic map of the Chugach National Forest, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1645-B, 16 p., 1 sheet, scale 1:250,000.
Rogers, R., and Hoyt, M., 1999, Mineral prospects on Chugach Alaska Corporation lands: Chugach Alaska Corporation in-house report, 10 p., 1 table, 10 maps.
Shacklette, H.T., 1965, Bryophytes associated with mineral deposits and solutions in Alaska: U.S. Geological Survey Bulletin 1198-C, p. C1-C18.
Smith, S.S., 1917, The mining industry in the Territory of Alaska during the calendar year 1916: U.S. Bureau of Mines Bulletin 153, 89 p.
Stejer, F.A., 1956, Pyrite deposits at Horseshoe Bay, Latouche Island, Alaska: U.S. Geological Survey Bulletin 1024-E, p. 107-122.
|Reporters||Jeff A. Huber and Carol S. Huber (Anchorage)|
|Last report date||10/15/2001|