|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||Bear Gulch is a 3-mile-long southwest-flowing tributary of Long Creek. Its confluence with Long Creek is near the town of Long. The coordinates given correspond to location 12 of Cobb (1972[MF405]), and mark the center of placer tailings marked on the USGS Ruby (B-5) Quadrangle map (1952, minor revisions in 1973), in section 32, T. 12 S., R. 17 E. of the Kateel River meridian. The location is accurate.|
The Bear Creek basin drains off of three separate rock units, and flows on or very near to a reverse fault contact between two distinct rock units of the Tozitna terrane. Puchner and others (1998) mapped intermediate to mafic intrusive rocks including gabbros and diorites on the eastern side of the valley. The western side consists of interbedded phyllites, schists, meta-graywackes, greenstones and marbles. The closest granitic bodies lie 6 miles away, toward the northeast and southeast.
Gold was first discovered on Bear Gulch in 1910 (Maddren, 1912). There are two pay streaks in Bear Gulch. The main one is in a low terrace southeast of the creek. The other is at a higher level and is less rich in gold (Eberlein and others, 1977). Cassiterite and silver accompanied the gold (Mertie, 1936). The stream gravels were mined by open-cut methods until about 1933.The main pay streak was 20 to 30 feet deep and up to 100 feet wide with 6 to 8 feet of gold-bearing gravel (Mertie, 1936). The two most productive claims produced a total of 24,000 to 29,000 ounces of gold between 1914 and 1933 with an average composition of nuggets being 857 parts Au per thousand and 135 parts Ag per thousand (Mertie, 1936). The gold was worn but not well-rounded, and included several nuggets weighing between 2 1/2 and 100 ounces apiece (Eberlein and others, 1977).
|Geologic map unit||(-155.49385264207, 64.407415258377)|
|Mineral deposit model||Placer Au (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary.|
|Workings or exploration||Gold was first discovered on Bear Gulch in 1910 (Maddren, 1912). There are two pay streaks in Bear Gulch: in a low terrace southeast of the creek, and at a higher level where gold grades are lower (Eberlein and others, 1977). The stream gravels were mined by open-cut methods until about 1933 (Mertie, 1936).|
|Indication of production||Yes; small|
|Production notes||The two most productive claims along Bear Creek produced a total of 24,000 to 29,000 ounces of gold between 1914 and 1933 (Eberlein and others, 1977).|
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.
|Reporters||C.E. Cameron (Alaska Division of Geological and Geophysical Surveys)|
|Last report date||3/22/2000|