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

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

Location: The site of the 1929 mining is in sec. 34, T. 8 N., R. 13 E, of the Fairbanks Meridian. Access is poor with no summer roads and only a winter tractor trail.
Geology: Boulder Creek, a tributary of Crooked Creek, is about 21 km long, and cuts quartzite schist and Tertiary granite before crossing the Hot Springs fault and entering the Tintina fault trench. The Tertiary granite is a light gray biotite monzogranite to syenogranite. Heavy-mineral concentrates from the granite contain 45% allanite, 15% chalcopyrite and smaller amounts of other minerals (Nelson and others, 1954). Fluorimetric tests on several other granite minerals indicated the presence of uranium (Nelson and others, 1954). A pebble count of the creek gravel north of the Hot Springs fault indicates a composition of 50 percent quartzite, 27 percent quartz-mica schist, 17 percent quartz, and 6 percent granite (Yeend, 1991). Quartz and schist boulders in the creek are generally about 0.5 meters in diameter, and occasional boulders are up to 1 meter (Yeend, 1991). Gold is generally found in the lower 3.5 feet of the 8 feet of bench gravel (Mertie, 1932, p. 250). The valley near past mining operations is about 70 to 100 meters wide, with fan gravel common at the mouths of small side gulches. Miners have reported two types of gold in the gravel: fine, flaky gold and coarse, rough gold with adhering quartz (Yeend, 1991). Mining on the creek was restricted to the 2-km stretch downstream from Greenhorn Gulch (Yeend, 1991). Operations in 1975 closed down due to excessive amounts of cassiterite in sluice boxes (Menzie, 1983, p. 40).
Workings: It is uncertain when mining began on Boulder Creek. Hydraulic mining of the bench gravel occurred in the early 1930's with gold being found in the lower 3.5 feet of the 8 feet of bench gravel (Mertie, 1932). Mining on the creek was restricted to the 2-km stretch downstream from Greenhorn Gulch (Yeend, 1991). Operations in 1975 closed down due to excessive amounts of cassiterite in sluice boxes (Menzie, 1983, p. 40).
Production: Mining has been reported (see workings/exploration); however, amount of production is unknown.

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

Other Databases

Link to USGS - Alaska:	CI008

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References