Crooked Creek

Mine, Probably inactive

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Pb
Ore minerals galena; gold; silver

Geographic location

Quadrangle map, 1:250,000-scale EA
Quadrangle map, 1:63,360-scale D-2
Latitude 64.9285
Longitude -141.6643
Nearby scientific data Find additional scientific data near this location
Location and accuracy 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).

Geologic setting

Geologic description

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 pay streak 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).
Geologic map unit (-141.666631505552, 64.9281998246206)
Mineral deposit model Placer Au (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Quaternary.

Production and reserves

Workings or exploration 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).
Indication of production Yes
Production notes 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.

References

MRDS Number A015132

References

Reporters R.L. Flynn; M.B. Werdon
Last report date 5/1/2002