|Quadrangle map, 1:250,000-scale||BN|
|Quadrangle map, 1:63,360-scale||A-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This placer mine comprises 3,500 feet of the channel of Crooked Creek, between an elevation of 350 and 450 feet; it that begins about one mile upstream from its mouth. Crooked Creek is a short, 2.3 mile long west tributary to Ophir Creek. The mouth of Crooked Creek is 7,500 feet upstream on Ophir Creek from the southern boundary of the Bendeleben quadrangle. This is locality 80 of Cobb (1972; MF 417; 1975; OFR 75-429).|
Geologic descriptionStream gravels of Crooked Creek merge with floodplain deposits of Ophir Creek where the pay streak was 250 feet wide, 6 feet thick, and contained 0.22 ounces Au per cubic yard (Collier and others, 1908; Smith and Eakin, 1911). The pay streak narrowed to 6 feet wide 0.25 mile upstream of the mouth. About three quarters of a mile above the mouth of Crooked Creek, the pay streak consisted of 5 feet of auriferous sandy clay mixed with limestone (marble) fragments; it was 20 feet wide and overlain by 6 feet of barren clay. At 1.25 miles above the mouth, the pay streak widened to 150 to 200 feet and consisted of auriferous yellow clay mixed with limestone (marble) boulders. Garnet, magnetite, and topaz were collected from placer concentrate near the mouth of the creek (Smith and Eakin, 1911). Much of the mining in the two decades before WW II, including dredging (Cobb, 1975, OFR 75-429), probably took place here. Bedrock in the area is metasedimentary schist and marble of a Lower Paleozoic assemblage (Till and others, 1986).
|Geologic map unit||(-163.699625693454, 65.0272745653323)|
|Mineral deposit model||Placer Au-PGE (Cox and Singer, 1986; model 39a)|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary; two or more cycles of placer development have occurred in the area.|
|Workings or exploration||Surface open-cut placer workings and dredging have taken place along this part of Crooked Creek.|
|Indication of production||Yes; small|
|Production notes||Placer gold from lower Crooked Creek was both coarse and rounded as well as sharp and angular with quartz attached (Smith and Eakin, 1911). Collier and others (1908) also noted fragile and crystalline placer gold that suggests a local source.|
Cobb, E.H., 1972, Metallic mineral resources map of the Bendeleben quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-417, 1 sheet, scale 1:250,000.
Cobb, E.H., 1975, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Bendeleben quadrangle, Alaska: U.S. Geological Survey Open-File Report 75-429, 123 p.
Collier, A.J., Hess, F.L., Smith, P.S., and Brooks, A.H., 1908, The gold placers of parts of Seward Peninsula, Alaska, including the Nome, Council, Kougarok, Port Clarence, and Goodhope precincts: U.S. Geological Survey Bulletin 328, 343 p.
Smith, P.S., and Eakin, H.M., 1911, A geologic reconnaissance in southeastern Seward Peninsula, and the Norton Bay-Nulato region, Alaska: U.S. Geological Survey Bulletin 449, 146 p.
|Reporters||Travis L. Hudson (Applied Geology)|
|Last report date||3/15/1999|