|Quadrangle map, 1:250,000-scale||CI|
|Quadrangle map, 1:63,360-scale||B-3|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Greenhorn Gulch extends about 1.5 mi north and 1.5 mi south of the coordinate intersection; it is a tributary of Boulder Creek. Mining activity in the 1970's and 1980's also has occurred at the junction with Tinhorn Gulch.|
The creek along Greenhorn Gulch flows north for approximately 5 km before joining Boulder Creek. Bedrock throughout the entire Greenhorn Gulch drainage is the Lower Schist unit described by Wiltse and others (1995) as slightly calcareous quartz-muscovite schist, porphyroblastic albite-quartz-chlorite-muscovite schist, and lesser amounts of quartzose porphyroblastic albite-chlorite schist and chlorite schist.An alluvium-covered bench on the west side of the gulch is 8 to 12 m above the valley bottom and grades into the bench in Boulder Creek. The creek gravel in Greenhorn Gulch is composed of boulders up to 70 cm in diameter, but are more commonly 10 to 30 cm across. The gravel is 1 to 2 meters thick over the schist bedrock and is as much as 30 meters wide (Yeend, 1991). A fragment of vein quartz with cavities from which sulfides had been weathered out assayed 24 oz. silver per ton and contained specks of free gold (Spurr, 1898, p. 293).
|Geologic map unit||(-145.07344881544, 65.4506310342245)|
|Mineral deposit model||Placer gold deposit (Cox and Singer, 1986; model 39a)|
|Mineral deposit model number||39a|
|Workings or exploration||There was small-scale placer mining reported in 1896, and 1911 to 1912; however, mining was hampered by the lack of water. Recent mining activity in the 1970s and 1980s has occurred on the creek junction with Tinhorn Gulch (Yeend, 1991; Menzie and others, 1983).|
|Indication of production||Yes; small|
|Production notes||A 2.5 oz gold nugget was recovered in the early days of mining, and vein quartz in the gravel reportedly contained finely disseminated free gold (Spurr, 1898).|
Additional commentsGreenhorn Gulch is the only part of the Boulder Creek drainage that has had significant placer mining activity. Greenhorn Gulch has also been called Greenhorn Creek but it should not be confused with the much less productive 'Greenhorn Creek' that is a tributary of Bottom Dollar Creek.
Barker, J.C., 1979, A trace element study of the Circle mining district, Alaska: U.S. Bureau of Mines Open-File Report 57-79, 74 p.
Brooks, A.H., 1907, The Alaskan mining industry in 1906: U.S. Geological Survey Bulletin 314-A, p. 19-39.
Cobb, E.H., 1972, Metallic mineral resources map of the Circle quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-391, 1 sheet, scale 1:250,000.
Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Circle quadrangle, Alaska: U.S. Geological Survey Open-File Report 76-633, 72 p.
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 77-168D, 132 p.
Ellsworth, C.E., 1912, Placer mining in the Fairbanks and Circle Disctricts: U.S. Geological Survey Bulletin 520-H, p. 240-245.
Ellsworth, C.E., and Davenport, R.W., 1913, Placer mining in the Yukon-Tanana region: U.S. Geological Survey Bulletin 542-F, p. 203-222.
Menzie, W.D., Foster, H.L., Tripp, R.B., and Yeend, W.E., 1983, Mineral resource assessment of the Circle quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-170-B, 61 p., 1 sheet, 1:250,000.
Mertie, J.B., Jr., 1932, Mining in the Circle district: U.S. Geological Survey Bulletin 824-D, p. 155-172.
Mertie, J.B., Jr., 1938, Gold placers of the Fortymile, Eagle, and Circle districts, Alaska: U.S. Geological Survey Bulletin 897-C, p. 133-261.
Prindle, L.M., 1913, A geologic reconnaissance of the Circle quadrangle, Alaska: U.S. Geological Survey Bulletin 538, 82 p.
Spurr, J.E., and Goodrich, H.B., 1898, Geology of the Yukon gold district, Alaska, with an introductory chapter on the history and present condition of the district by H.B. Goodrich in Walcott, C.D., editor, Eighteenth annual report of the United States Geological Survey to the Secretary of the Interior, 1896-1897: Part III - Economic geology: U.S. Geological Survey 18th Annual Report, Part 3, p. 87-392.
Wiltse, M.A., Reger, R.D., Newberry, R.J, Pessel, G.H., Pinney, D.S., Robinson, M.S., and Solie, D.N., 1995, Bedrock geologic map of the Circle mining district, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 95-2B, 1 sheet, scale 1:63,360.
|Reporters||C.J. Freeman, J.R. Guidetti Schaefer, A.S. Clements (Avalon Development Corporation)|
|Last report date||9/9/1998|