Eagle Creek; Mastodon Fork; Miller Fork; Cripple Creek Mine, Circle District, Yukon-Koyukuk Borough, Alaska, USA

Eagle Creek was the first area in Alaska where the gravels were elevated during placer mining. A gin pole and steam scraper were used to elevate and dump tailings alongside the cut. These rock piles can still be seen along Mastodon Fork (Yeend, 1991).
Location: The location is the intersection of Miller Fork and Mastodon Fork with Eagle Creek. Placer mining extended about 2 mi downstream on Eagle Creek and about 1 mile up Mastodon Fork; no mining was reported on Miller Fork.
Geology: Bedrock is mainly quartzose schists with many quartz veins. Mastodon Fork, Miller Fork and Cripple Creek drain an area underlain by the Upper Quartzite bedrock unit described by Wiltse and others (1995) as light to medium-gray fine- to medium-grained, quartzite, quartz-muscovite schist, and medium-gray to greenish-gray, fine- to medium-grained porphyroblastic-albite-chlorite-muscovite-quartz schist. Eagle Creek itself is underlain by the polylithic Upper Schist unit which is dominated by thinly layered pelitic quartz-muscovite schist, muscovite-quartz schist, chlorite-quartz-muscovite schist and distinct intervals of garnetiferous, calcareous albite-porphyroblastic muscovite-chlorite schist with interlayered impure marbles. Gold is located in the lowest several feet of gravel, in clay near bedrock, on bedrock, and in the top two feet of fractured bedrock (Spurr, 1898). The paystreak is 150 to 200 feet wide extending down Mastodon Fork and Eagle Creek in stream gravels 5 to 20 feet thick which are overlain by 2 to 15 feet of muck (Mertie, 1938). Since about 1901, mining has been almost continuous on the creek. Open cut and drift mining methods were replaced by hydraulic plants in 1906. Prior to 1980 most of the rich gravel in Eagle and almost all of Mastodon Fork was mined. Since 1980, a large operation has been remining some of the hydraulic tailings in Eagle Creek and has mined some areas of gravel along the creek margins that were not mined by earlier operations. The width of the mined area across the creek is up to 100 meters (Yeend, 1991, p. 63).
Workings: Since about 1901, mining has been almost continuous on the creek. Open cut and drift mining methods were replaced by hydraulic plants in 1906. Prior to 1980 most of the rich gravel in Eagle and almost all of Mastodon Fork was mined. Since 1980, a large operation has been remining some of the hydraulic tailings in Eagle Creek and has mined some areas of gravel along the creek margins that were not mined by earlier operations. The width of the mined area across the creek is up to 100 meters (Yeend, 1991, p. 63).
Production: Ground mined in 1895 was reported to have averaged 3 ounces of gold per man per day. During 1897, 75 miners produced approximately 3,750 oz of gold, with only 4 of the 46 claims being worked (Dunham, 1898). Production through 1906 was about 29,000 oz of gold (Brooks, 1907). Gold fineness was 883 Au, 108 Ag (Mertie, 1938). Ed Lapp and Sons Mining (ELSM) reported production on Eagle Creek in 1994 and 1996 (Swainbank and others, 1994,1996).

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

References:
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