Black Creek

Mine, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Cr; Hg; Nb; Sn; Pt; W
Ore minerals arsenopyrite; argentopyrite; cassiterite; chromite; cinnabar; gold; ilmenite; ilmenorutile; magnetite; scheelite
Gangue minerals zircon

Geographic location

Quadrangle map, 1:250,000-scale ID
Quadrangle map, 1:63,360-scale B-4
Latitude 62.4379
Longitude -157.93721
Nearby scientific data Find additional scientific data near this location
Location and accuracy Black Creek has been placered for its entire length of about 1.6 miles. The coordinates are at the midpoint of the deposit about 0.5 mile north-northeast of the center of section 14, T. 27 N., R. 47 W., of the Seward Meridian. The location is accurate. Black Creek is locality 31 of Cobb (1972 [MF 363]).

Geologic setting

Geologic description

Black Creek is a narrow, 1.5-mile-long stream that enters Otter Creek near Discovery camp. The creek dissects an altered monzodiorite pluton and its associated hornfels which are probably the source of much of the placer gold and heavy minerals in the Black Creek placer. The auriferous fluvial gravels varied from 10 to 12 feet thick; they were overlain by 6 to 16 feet of overburden (Mertie, 1936; Cobb, 1976 [OFR 76-576]). In addition to gold, the principal heavy minerals identified in concentrates include arsenopyrite, argentopyrite, cassiterite, cinnabar, ilmenorutile, scheelite, chromite, ilmenite, magnetite, and zircon. The gold fineness averages 819; this is significantly lower than the fineness of the gold from other gold placers in the Iditarod district (for example ID104 and ID111). Samples of concentrates collected in 1981 contained 6.51 percent tungsten, 470 parts per million (ppm) niobium, 3.35 percent chromium, 1,300 parts per billion (ppb) platinum, and 1,433 ppm lead (Bundtzen, Cox, and Veach, 1987).
Open cuts were first used to mine Black Creek in 1910. From 1911 to 1915, gravel near the mouth of Black Creek was drift mined as the overburden was too thick to remove using simple excavation techniques (Mertie, 1936). From 1916 to 1918, The Union Construction Company (later North American Dredging Company) mined from the mouth of Black Creek to a point two-thirds of the way up the creek. Otter Creek Dredging Company (John Miscovich) mined from the late 1970s to 1981 near the mouth of Black Gulch and Glen Gulch with backhoe and bulldozer. There has been no mining since 1981.
From 1910 to 1981, 27,925 ounces of gold was produced from Black Creek (Bundtzen and others, 1992; Miller, Bundtzen, and Gray, 2005). From 1916 to 1918, the Union Construction Company dredge alone produced 22,125 ounces of gold, or nearly 80 percent of the gold produced from Black Creek.
Geologic map unit (-157.93961258931, 62.4372152750331)
Mineral deposit model Placer Au deposit (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Probably Quaternary.

Production and reserves

Workings or exploration Open cuts were first used to mine Black Creek in 1910. From 1911 to 1915, gravel near the mouth of Black Creek, was drift mined as the overburden was too thick to remove using simple excavation techniques (Mertie, 1936). From 1916 to 1918, The Union Construction Company (later North American Dredging Company) mined from the mouth of Black Creek to a point two-thirds of the way up the creek. Otter Creek Dredging Company (John Miscovich) mined from the late 1970s to 1981 near the mouth of Black Gulch and Glen Gulch with backhoe and bulldozer. There has been no mining since 1981.
Indication of production Yes
Production notes From 1910 to 1981, 27,925 ounces of gold was produced from Black Creek (Bundtzen and others, 1992; Miller, Bundtzen, and Gray, 2005). From 1916 to 1918, the Union Construction Company dredge alone produced 22,125 ounces of gold, or nearly 80 percent of the gold produced from Black Creek.

References

MRDS Number A015074; A015075; D002699

References

Bundtzen, T.K., Cox, B.C., and Veach, N.C., 1987, Heavy mineral provenance studies in the Iditarod and Innoko districts, western Alaska: Process Mineralogy VII, The Metallurgical Society, p. 221-246.
Reporters T.K. Bundtzen (Pacific Rim Geological Consulting, Inc.), M.L. Miller (U.S. Geological Survey); and C.C. Hawley (Hawley Resource Group)
Last report date 5/21/2003