Crooked Creek Mine, Eagle Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Crooked Creek Mine	Mine
Eagle Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

Location: Crooked Creek is an 8-mile-long north tributary of the Seventymile River. The placer deposits are located in the lower 2 miles of Crooked Creek, downstream of Eldorado Creek; the coordinates are about 1 mile upstream of the mouth of Crooked Creek, in section 9, T. 1 N., R. 30 E., of the Fairbanks Meridian. Crooked Creek is locality 29 of Cobb (1972 [MF-393]), locality 19 of Eberlein and others (1977), and locality 12 of Burleigh and Lear (1994).
Geology: The rocks along Crooked Creek are primarily Cretaceous to Pliocene conglomerate with lesser sandstone and shale (Clark and Foster, 1971; Foster, 1976). Trachyte porphyry and other dikes cut the sedimentary rocks (Clark and Foster, 1971). Mining in 1936 took place about 2 miles upstream of the mouth of the creek, where the paystreak was about 270 feet wide (Mertie, 1938). In general, 3 to 4 feet of muck covered the gravel, which is generally 5 to 6 feet thick, but locally as much as 8 feet thick. The gravel consists of well-rounded cobbles of rather uniform size; some boulders reach 2 feet in diameter. Gold was recovered from the entire section of gravel, rather than concentrated near bedrock. The gold was fine-grained, and some small silver nuggets were also recovered. Three assays of placer gold collected from Crooked Creek in 1934 and 1935 averaged 902 parts of gold and 92 parts of silver per thousand, the highest grade in the Seventymile area (Mertie, 1938). Mertie (1942) later reported 20 assays of placer gold from Crooked Creek that averaged 908 parts of gold and 88 parts of silver per thousand. Galena and hematite were also recovered from sluice boxes on Crooked Creek (Clark and Foster, 1971). Arsenic was found in all stream-sediment samples collected from Crooked Creek by Clark and Foster (1971). No workable placers on Crooked Creek have been found above the mouth of Eldorado Creek, which heads against the same ridge as Lucky Gulch (see EA020). Mertie (1942) suggests that gold in Crooked Creek and Lucky Gulch is derived from the area between them. Placer gold has been produced on the Seventymile River (see EA025) near the mouth of Crooked Creek. There are reports of mining on Crooked Creek for the most years from 1909 to 1940. A hydraulic plant was installed in 1916 (Brooks, 1918), and it was operating in 1921 (Brooks, 1923). In 1936, Crooked Creek had the only good-size hydraulic plant in the Seventymile River basin (Mertie, 1938). Mining in 1936 on Crooked Creek was taking place about 2 miles upstream from its mouth; earlier mining was located farther downstream (Mertie, 1938).
Workings: There are reports of mining on Crooked Creek for the most years from 1909 to 1940. A hydraulic plant was installed in 1916 (Brooks, 1918), and it was operating in 1921 (Brooks, 1923). In 1936, Crooked Creek had the only good-size hydraulic plant in the Seventymile River basin (Mertie, 1938). Mining in 1936 on Crooked Creek was taking place about 2 miles upstream from its mouth; earlier mining was located farther downstream (Mertie, 1938).
Age: Quaternary.
Production: Three assays of placer gold collected from Crooked Creek in 1934 and 1935 averaged 902 parts of gold and 92 parts of silver per thousand, the highest grade in the Seventymile area (Mertie, 1938). Mertie (1942) later reported 20 assays of placer gold from Crooked Creek that averaged 908 parts of gold and 88 parts of silver per thousand.

Commodities (Major) - Au; (Minor) - Ag, Pb
Development Status: Yes
Deposit Model: Placer Au (Cox and Singer, 1986; model 39a).

Other Databases

Link to USGS - Alaska:	EA026

Other Regions, Features and Areas containing this locality

References