Beaver Creek Prospect (tributary of Big Creek), Ruby Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Beaver Creek Prospect (tributary of Big Creek)	Prospect
Ruby Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Beaver Creek lies within the Doyon, Limited Ruby Village Block. For more information, contact Doyon, Limited.
Location: Beaver Creek is located on the north side of the Beaver Creek valley, near its junction with Thirteenmile Creek. Coordinates fall on location 1 of Cobb (1972 [MF405]), in section 26, T. 9 S., R. 17 E. of the Kateel River meridian. The location is accurate within 1/2 mile. Beaver Creek lies within Doyon, Limited Ruby village land.
Geology: The galena deposit near Beaver Creek was first discovered around 1920 (Brooks, 1922). The country rock is fractured quartz-mica schist and phyllite containing siliceous and calcareous bands (Thomas, 1964). The Beaver Creek site contains two northeast-striking, near-vertical zones of silver-rich, galena-bearing gossan (Northstar Exploration Company, 1999). The zones are as much as 500 feet long, 6 feet wide, and 10 feet deep (Northstar Exploration Company, 1999). The gossan zones contain abundant cellular boxworks that parallel schistocity. Sulfide minerals from Beaver Creek exhibit crosscutting and recrystallized textures that are clearly indicate remobilization and are not typical of syngenetic ore deposits (Northstar Exploration Company, 1999). Lenticular veins of silver-bearing galena occur within gossan, with varied amounts of cerussite, anglesite, rhodochrosite, manganese oxides, gold, pyrite, ruby silver, malachite, and azurite (White and Stevens, 1953). Nokleberg and others (1994) also report sphalerite. Assays of the ore contain 1.47 to 82 ounces of silver per ton, 8.7 percent to 15.3 percent lead, 0.08 to 0.89 percent zinc, and 0.02 percent copper (Thomas, 1964). A trace of gold was also reported. The maximum eU was 0.003 percent (White and Stevens, 1953). A resource estimate by Nockleberg and others (1994) is 13,600 tonnes of ore grading 103 grams silver per ton, 0.8 percent gold, and 0.5 percent copper, with an additional 19,100 tonnes containing 26.1 grams silver per ton, 4.2 percent lead, 0.16 percent zinc, and 0.2 percent copper (Nokleberg and others, 1994). The Beaver Creek prospect lies within 250 m of the Angayucham-Tozitna thrust fault, and this fault could have played a significant role in controlling the location of sulfide mineralization (Northstar Exploration Company, 1999). While the Beaver Creek mineralization could be plutonic-related, sulfur isotope values from the nearby and mineralogically similar Perseverance mine yield results more consistent with a remobilized syngenetic massive sulfide deposit (Northstar Exploration Company, 1999). The deposit was explored by trenches, pits, and short adits in the early 1920s. Beaver Creek was explored by the U.S. Bureau of Mines in 1960. It now lies within the Doyon, Limited Ruby Village Block, and has been sampled and geologically mapped from 1993 to 1998 (Northstar Exploration Company, 1999).
Workings: The deposit has been explored by trenches, pits, and short adits during the 1920s. The deposit was also explored by the U.S. Bureau of Mines in 1960. Workings include a 40-foot shaft, 2 other shallow shafts, as well as an adit and drift tunnels. About 3,100 linear feet of trenches were excavated from 11 trenching sites in 1960 (Thomas, 1964).
Alteration: Weathering of sulfides has produced a base metal-rich gossan.
Reserves: A resource estimate by Nockleberg and others (1994) is 13,600 tonnes of ore grading 103 grams silver per ton, 0.8 percent gold, and 0.5 percent copper, with an additional 19,100 tonnes containing 26.1 grams silver per ton, 4.2 percent lead, 0.16 percent zinc, and 0.2 percent copper (Nokleberg and others, 1994).

Commodities (Major) - Pb; (Minor) - Ag, Au, Cu
Development Status: Yes; small
Deposit Model: Remobilized syngenetic massive sulfide? (Cox and Singer, 1986; model 24b).

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Link to USGS - Alaska:	RB012

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References