Napoleon Creek Mine, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Napoleon Creek Mine	Mine
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

Location: Napoleon Creek is an east tributary of the South Fork of the Fortymile River about 7 miles northeast of Chicken. Placer tailings are shown on the U.S. Geological Survey 1:63,360-scale topographic map of the Eagle A-2 quadrangle (1956; revised in 1971). The coordinates correspond to the midpoint of the tailings shown near the mouth of Napoleon Creek in section 20, T. 27 N., R. 19 E., of the Copper River Meridian. The location is accurate. This record also includes references to additional placer workings shown approximately 1 mile upstream and to terrace gravels that were mined near the mouth of Napoleon Creek. This site is locality 96 of Burleigh and Lear (1994), locality 44 of Eberlein and others (1977), and locality 58 of Cobb (1972 [MF-393]).
Geology: The rocks in the upper part of Napoleon Creek consist of Paleozoic amphibolite-facies metamorphic rocks that have been intruded by undifferentiated Jurassic granitic rocks (Foster, 1976; Werdon and others, 2001). The Napoleon pluton crops out at the head of the creek; the lode gold deposit (EA115) within the pluton is the likely source for at least some of the placer gold in Napoleon Creek. Bedrock near the mouth of Napoleon Creek consists mainly of unmetamorphosed Tertiary conglomerate and lesser sandstone, tuff, and local coal-bearing units (Spurr, 1898; Foster, 1976). These Tertiary rocks are preserved within a fault-bounded, structurally down-dropped basin. Near the eastern fault contact of the Tertiary sedimentary rocks with the older metamorphic rocks, Tertiary gabbro bodies intrude both units (Mertie, 1938; Werdon and others, 2001). At the mouth of the creek the valley is about 90 yards wide and is bordered by steep conglomerate bluffs (Mertie, 1938). Near the mouth of Napoleon Creek, terrace gravels depositionally overlie the Tertiary conglomerate and occur as high as 200 meters above the creek (Pinney, 2001). Placer mining on Napoleon Creek occurred near the mouth of the creek, at a site approximately 1.5 miles upstream, and on terrace benches. Gravel in lower Napoleon Creek is approximately 8 to 18 feet thick,and the placer gold was mainly found on top of bedrock or in cracks within bedrock (Mertie, 1938). The gold is coarse grained and irregularly shaped. Nuggets heavier than 17 ounces have been recovered. Nuggets a half-inch in diameter or more are common, and the gold fineness is about 851 to 870 parts of gold per thousand (Mertie, 1938; Smith, 1941 [B 910-C]). In 1953, the gold being recovered had a fineness ranging from 870 to 872 parts of gold per thousand (Saunders, 1953). A high bench on the north side of the creek had rich pockets of gold on Tertiary bedrock. This bench is about 170 meters above Napoleon Creek (Yeend, 1992), and the gravels are approximately 40 meters thick. Vein quartz has been found in the stream gravels (Spurr, 1898). Spurr (1898) considered that the placer gold was derived from an older placer. The lode gold deposit within the Napoleon pluton (see EA115) at the head of the creek is a likely source for at least some of the placer gold in Napoleon Creek. Minor platinum has been found in Napoleon Creek. A likely source for the platinum is the Jurassic platinum-group-bearing clinopyroxenite bodies located on the ridge at the head of Napoleon Creek (Werdon and others, 2000). Placer gold on Napoleon Creek was first discovered in 1893 (Spurr, 1898); since then, gravels from both the active stream and high bench terraces have been mined. The creek was mined intermittently from around 1898 to at least 1936. Prospecting on benches, as well as open-cut mining near the mouth of the creek, occurred in 1912 (Ellsworth and Davenport, 1913). The north valley walls were being mined in 1936 (Mertie, 1938), and Foster (1969 [B 1271-G]) reportd that rich pay streaks were found on the high terrace. In 1969, Foster and Keith (1969) noted that the placer mine on the bench had been abandoned. In 1990, as well as from 1999 to 2001, there was an active placer mining operation on Napoleon Creek (Yeend, 1992). In 1896, the only paying claims were the two nearest the mouth where gold was first discovered (Spurr, 1898). By 1899, gold had been produced in commercial quantities (Brooks, 1900). Production on Napoleon Creek between 1904 and 1907, combined with that from Montana (EA067), Buckskin (EA113), Dome Creek (EA079), Eagle, and Twin Creeks, totaled about 122 fine ounces (Eberlein and others, 1977). Production from discovery to 1936 was worth about $200,000 (gold at $20.76 per ounce) (Mertie, 1938). The terrace 170 meters above Napoleon Creek yielded about 1,300 ounces of gold from an area no much larger than a quarter of an acre (Yeend, 1992).
Workings: Placer gold on Napoleon Creek was first discovered in 1893 (Spurr, 1898); since then, gravels from both the active stream and high bench terraces have been mined. The creek was mined intermittently from around 1898 to at least 1936. Prospecting on benches, as well as open-cut mining near the mouth of the creek, occurred in 1912 (Ellsworth and Davenport, 1913). The north valley walls were being mined in 1936 (Mertie, 1938), and Foster (1969 [B 1271-G]) reported that rich pay streaks were found on the high terrace. In 1969, Foster and Keith (1969) noted that the placer mine on the bench had been abandoned. In 1990, as well as from 1999 to 2001, there was an active placer mining operation on Napoleon Creek (Yeend, 1992).
Age: Quaternary.
Production: In 1896, the only paying claims were the two nearest the mouth where gold was first discovered (Spurr, 1898). By 1899 gold had been produced in commercial quantities (Brooks, 1900). Production on Napoleon Creek between 1904 and 1907, combined with that from Montana (EA067), Buckskin (EA113), Dome Creek (EA079), Eagle, and Twin Creeks, totaled about 122 fine ounces (Eberlein and others, 1977). Production from discovery to 1936 was worth about $200,000 (gold at $20.76 per ounce) (Mertie, 1938).

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

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Link to USGS - Alaska:	EA123

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References