Porcupine Creek Mine, Circle Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Porcupine Creek Mine	Mine
Circle Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: 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.
Geology: 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 1980's was 3 to 8 meters thick with a paystreak 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 1890's but mining was intermittent and on a small scale until the 1930's. Hydraulic operations began in 1932 and a drag-line excavator was used to handle the tailings. Some mining occurred in the late 1950's and (or) early 1960's. 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).
Workings: Placer gold was discovered in the 1890's but mining was intermittent and on a small scale until the 1930's. Hydraulic operations began in 1932 and a drag-line excavator was used to handle the tailings. Some mining occurred in the late 1950's and (or) early 1960's. 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).
Production: Yields were from 0.01 to 0.0125 ounces per cubic yard (Yeend, 1991).

Commodities (Major) - Au; (Minor) - Sn, W
Development Status: Yes; small
Deposit Model: Placer gold deposit (Cox and Singer, 1986; model 39a)

Other Databases

Link to USGS - Alaska:	CI046

Other Regions, Features and Areas containing this locality

References