Bunker Hill

Prospect, Inactive

Commodities and mineralogy

Main commodities Au; Cu
Ore minerals chalcopyrite; gold; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SO
Quadrangle map, 1:63,360-scale C-4
Latitude 64.595
Longitude -163.764
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is on the low ridge between Eldorado Creek (ARDF SO007) and Lost Creek, 1.7 miles north-northwest of Bluff. It is at an elevation of about 320 feet and is locality 20 of Cobb (1972, MF 445; 1978, OF 78-181).

Geologic setting

Geologic description

A 5.5-foot-wide quartz vein or silicified zone at a marble-schist contact carries sparse chalcopyrite, pyrite, malachite, and azurite; the central 18 inches is barren (Cathcart, 1922). Assays reported by early workers ran up to up to $80 per ton of gold (3.9 ounces per ton) (Cathcart, 1922). Bedrock in this area is part of a lower Paleozoic metasedimentary marble-schist assemblage (Herreid, 1965; Till and others, 1986). The mineralization may be mid-Cretaceous in age, the age of some lode gold deposits on southern Seward Peninsula. The southern Seward Peninsula lode gold deposits formed as a result of mid-Cretaceous metamorphism (Apodoca, 1994; Ford, 1993, Ford and Snee, 1996; Goldfarb and others, 1997) that accompanied regional extension (Miller and Hudson, 1991) and crustal melting (Hudson, 1994). This higher temperature metamorphism was superimposed on high pressure/low temperature metamorphic rocks of the region.
Geologic map unit (-163.766586001936, 64.5942635308616)
Mineral deposit model Quartz vein or replacement at marble-schist contact; possibly low sulfide Au quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Not known - possibly mid-Cretaceous.
Alteration of deposit Silicification is indicated.

Production and reserves

Workings or exploration Exploration consists of two, old shallow trenches, 2 feet deep and 20 feet long (Cathcart, 1922).
Indication of production None

References

MRDS Number A012585

References

Apodoca, L.E., 1994, Genesis of lode gold deposits of the Rock Creek area, Nome mining district, Seward Peninsula, Alaska: Boulder, Colorado, University of Colorado, Ph.D. dissertation, 208 p.
Ford, R.C., 1993, Geology, geochemistry, and age of gold lodes at Bluff and Mt. Distin, Seward Peninsula, Alaska: Golden, Colorado School of Mines, Ph.D. dissertation, 302 p.
Ford, R.C., and Snee, L.W., 1996, 40Ar/39Ar thermochronology of white mica from the Nome district, Alaska--The first ages of lode sources to placer gold deposits in the Seward Peninsula: Economic Geology, v. 91, p. 213-220.
Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Hudson, T.L., 1994, Crustal melting events in Alaska, in Plafker, G., and Berg, H. C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, Vol. G-1, p. 657-670.
Reporters Travis L. Hudson (Applied Geology)
Last report date 8/19/1999