|Quadrangle map, 1:250,000-scale||RB|
|Quadrangle map, 1:63,360-scale||B-5|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Trail Creek is an east-flowing tributary of the Sulatna River. Coordinates given correspond to location 18 of Cobb (1972 [MF-405]), and represent the approximate center of placer tailings and the mine marked on the USGS Ruby B-5 topographic map (1952, revised in 1973), in section 3, T. 13 S., R. 18 E. of the Kateel River meridian. The location is accurate.|
The bedrock underlying Trail Creek is phyllite, schist, and shaly slate, though the stream flows close to a contact between greenstone and schist (Eberlein and others, 1977). Some bedrock is highly pyritiferous. The gravels found in the creek are composed of subangular cobbles of greenstone, quartzite, carbonaceous shale, chert, and boulders of vein quartz (Mertie, 1936).
Placer gold was discovered on Trail creek in 1911, and intermittent mining continued along the creek until at least 1991 (Eberlein and others, 1977; Swainbank and others, 1991; Bundtzen and others, 1992). The pay streak was found along 2 miles along the valley, although gold was reported to be present as far as 17 miles downstream (Eakin, 1914 [B578]). Eakin (1914 ) reported the depth to bedrock is about 40 feet in the upper valley and 70 feet 7 miles downstream (Eakin, 1914). The ground in the upper 3 miles where most mining took place is generally about 25 to 35 feet deep (Mertie and Harrington, 1916). Gold is found in the base of 1 to 6 feet of gravel and on top of bedrock (Mertie, 1936). The gold is irregularly distributed within the gravel, and richer ground was reported at the mouths of small tributary gulches (Mertie and Harrington, 1916). The ground ran about 0.036 to 0.109 ounces of gold per square foot of bedrock (Mertie, 1936). Prospects and mining activity are found from Elephant Creek to Little Creek, along the right limit of Trail Creek (Jim Johnson, oral communication, 2000).The gold is both rough and well-rounded, suggesting two different sources (Cobb and Chapman, 1981). It is mostly fine-grained; however, 10 percent of the gold is present in larger nuggets (Mertie and Harrington, 1916; Cobb and Chapman, 1981). The largest nugget was about 14.5 ounces. The mean of multiple assays of the gold showed 838 parts gold per thousand and 152 parts silver per thousand (Mertie, 1936). The gold is accompanied by sand-sized cassiterite, abundant pyrite, and minor galena and scheelite (Mertie and Harrington, 1916; Mertie, 1936; Joesting, 1943; Chapman and others, 1963).
|Geologic map unit||(-155.278020214461, 64.3899811158142)|
|Mineral deposit model||Placer Au (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary.|
|Workings or exploration||Placer gold was discovered on this creek in 1911, and intermittent mining continued along the creek until at least 1991 (Eberlein and others, 1977; Swainbank and others, 1990; Bundtzen and others, 1992).|
|Indication of production||Yes; small|
|MRDS Number||A015540; D002617|
Bundtzen, T.K., Swainbank, R.C., Wood, J.E., Clough, A.H., 1991 (1992), Alaska's Mineral Industry 1991: Alaska Division of Geological & Geophysical Surveys, Special Report 46, 89 p.
Chapman, R.M., Coats, R.R., and Payne, T.G., 1963, Placer tin deposits in central Alaska: U.S. Geological Survey Open-File Report 239, 53 p.
Cobb, E.H., 1972, Metallic mineral resources map of the Ruby quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-405, 1 sheet, scale 1:250,000.
Cobb, E.H., and Chapman, R.M., 1981, Mineral occurrences (other than mineral fuels and construction materials) in the Kantishna River and Ruby quadrangles, Alaska: U.S. Geological Survey Open-File Report 81-170, 94 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 77-168-D, 132 p., 1 sheet, scale 1:1,000,000.
Joesting, H.R., 1943, Strategic mineral occurrences in interior Alaska, supplement to pamphlet No. 1: Alaska Territorial Department of Mines Pamphlet 2, 31 p.
Mertie, J.B., Jr., 1936, Mineral deposits of the Ruby-Kuskokwim region, Alaska: U.S. Geological Survey Bulletin 864-C, p. 115-245.
Mertie, J.B., Jr., and Harrington, G.L., 1916, Mineral resources of the Ruby-Kuskokwim region, in Brooks, A.H., and others, Mineral Resources of Alaska, Report on Progress of Investigations in 1915: U.S. Geological Survey Bulletin 642-H, p. 223-266.
|Reporters||C.E. Cameron (Alaska Division of Geological and Geophysical Surveys)|
|Last report date||3/22/2000|