Porcupine Creek

Mine, Active

Commodities and mineralogy

Main commodities Au
Other commodities Sn; W
Ore minerals cassiterite; gold; scheelite

Geographic location

Quadrangle map, 1:250,000-scale CI
Quadrangle map, 1:63,360-scale C-4
Latitude 65.548
Longitude -145.504
Nearby scientific data Find additional scientific data near this location
Location and accuracy The location is the center of a placered area that extends for about 1500 ft along Porcupine Creek. The area was mined in the 1930's, just upstream from the mouth of Yankee Creek. The location of more recent mining includes areas both up and downstream from the older placers.

Geologic setting

Geologic description

Bedrock underlying Porcupine Creek is the Lower Schist unit described by Wiltse and others (1995) as a slightly calcareous quartz-muscovite schist, porphyroblastic-albite-quartz-chlorite-muscovite schist, and lesser amounts of quartzose porphyroblastic-albite-chlorite schist and chlorite schist.
Placers mined in 1936 consisted of about 13 feet of gravel overlain by about 2 feet of muck. Gravel being mined in the 1980s was 3 to 8 meters thick with a pay streak 30 to 70 meters wide. The gravel is composed mostly of bedrock material. Most pebbles do not exceed a foot in diameter; however, some boulders as large as 3 feet in diameter have been recovered in mining operations. Gold is found mainly on and in bedrock and is coarse, ragged and shotty (Mertie, 1938). Numerous nuggets, some up to 2 to 3 ounces, have been found, but these had considerable amounts of attached quartz (Mertie, 1938). A four ounce nugget was recently recovered, and an 8 and one half ounce nugget was reported recently that is the largest nugget known from the area (Menzie and others, 1983, p. 50). Weighted mean of gold mined in 1934 and 1935 shows a fineness of 822 Au and 172 Ag (Mertie, 1938). Along with the gold, cassiterite and scheelite also can be found (Menzie and others, 1983, p. 50).
Placer gold was discovered in the 1890s but mining was intermittent and on a small scale until the 1930s. Hydraulic operations began in 1932 and a drag-line excavator was used to handle the tailings. Some mining occurred in the late 1950s and (or) early 1960s. Two operations were active in 1975 and activity was reported in 1980 and 1981 (Menzie and others, 1983, p. 50). Placer operations by Mack Rite and Harold Dunham were conducted in 1991 (Bundtzen and others, 1991, p. 32). Paul and Company conducted various actvities in 1992, including stripping, exploration, sluicing and reclamation (Swainbank and others, 1992). Paul and Company continued mining in 1993 and 1994. In 1994, they mined approximately 85,000 cubic yards (Swainbank and others, 1994, p. 28).
Geologic map unit (-145.506468031078, 65.5476248649742)
Mineral deposit model Placer gold deposit (Cox and Singer, 1986; model 39a)
Mineral deposit model number 39a

Production and reserves

Workings or exploration Placer gold was discovered in the 1890s but mining was intermittent and on a small scale until the 1930s. Hydraulic operations began in 1932 and a drag-line excavator was used to handle the tailings. Some mining occurred in the late 1950s and (or) early 1960s. Two operations were active in 1975 and activity was reported in 1980 and 1981 (Menzie and others, 1983, p. 50). Placer operations by Mack Rite and Harold Dunham were conducted in 1991 (Bundtzen and others, 1991, p. 32). Paul and Company conducted various activities in 1992, including stripping, exploration, sluicing and reclamation (Swainbank and others, 1992). Paul and Company continued mining in 1993 and 1994. In 1994, they mined approximately 85,000 cubic yards (Swainbank and others, 1994, p. 28).
Indication of production Yes; small
Production notes Yields were from 0.01 to 0.0125 ounces per cubic yard (Yeend, 1991).

References

MRDS Number A012238

References

Reporters C.J. Freeman, J.R. Guidetti Schaefer, A.S. Clements (Avalon Development Corporation)
Last report date 9/9/1998