Bear Gulch, Ruby Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Bear Gulch	Group of Mines
Ruby Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: 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.

Geology: 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 (ca. 10 km) 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 (ca. 9 m) deep and up to 100 feet (ca. 30 m) wide, with 6 to 8 feet (2.44 m) of gold-bearing gravel (Mertie, 1936). The two most productive claims produced a total of 24,000 to 29,000 ounces (1.1 ton) 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 (3.78 kg) apiece (Eberlein and others, 1977).

Workings: 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).

Age: Quaternary.

Production: The two most productive claims along Bear Creek produced a total of 24,000 to 29,000 ounces (1.1 t) of gold between 1914 and 1933 (Eberlein and others, 1977).

Commodities (Major): - Au; (Minor) - Ag, Sn

Development Status: Yes; small

Deposit Model: Placer Au (Cox and Singer, 1986; model 39a).

Other Databases

Link to USGS - Alaska:	RB023

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References