Yellow Jacket Mining District, Lemhi County, Idaho, USAi

Regional Level Types
Yellow Jacket Mining District	Mining District
Lemhi County	County
Idaho	State
USA	Country

The Yellowjacket District, in general terms, includes the area drained by Yellowjacket Creek. It is bound on the northeast by the Blackbird District, on the northwest by the Wilson Creek District, and on the southeast by the Gravel Range District.

Gold deposits were first discovered in the district during 1868. A 5-stamp mill was constructed in 1875 and expanded to 10 stamps in 1882 to process ore from the Yellowjacket, the principal mine. A 20-stamp amalgamation concentrator was built in 1894 and expanded to 60 stamps and a capacity of 100-150 tons per day in 1896 (Gerry, 1912, p. 575 and 1916, p. 625). A 350 ton per day gravity/flotation mill built in 1991 is currently at the mine site. Elsewhere in the district, a 10-stamp mill was built at the Columbia mine and a 5-stamp mill at the Black Eagle (Umpleby, 1913, p. 166).

According to Umpleby (1913, p. 166), production from the district prior to 1913 was about $450,000 when gold was about $20 per troy ounce. Most probably came from the Yellowjacket mine. Production from the Yellowjacket mine since 1987 totals 13,463 ounces of gold (John Lawrence, U.S. Antimony Corporation, personal communication, February 1997).

Production from the Continental-Columbia mineral belt, located about 1.5 miles southwest of the Yellowjacket mine, is sketchy. The mines along the belt have produced at least 618 tons of ore which yielded 466 ounces of gold, 1.300 ounces of silver, 13,635 pounds of copper, and 11,341 pounds of lead (Fisher and Johnson, 1987, p. 104-105; USBM records).

Mineralization at the Yellowjacket mine and along the Continental-Columbia belt consists of quartz veins, lenses, and veinlets in quartzitic and slightly calcareous beds of the Yellowjacket Formation. The veins favor a northeast trend and contain pyrite, chalcopyrite, galena, and tetrahedrite. The country rock has been fractured, locally brecciated, and intruded by lamprophyric, granophyric, and granitic dikes. Breccia zones along the Continental-Columbia belt consist of brecciated quartzite cemented by quartz and calcite. The breccia zones also contain pyrite, chalcopyrite, galena, and tetrahedrite.

Resources along the Continental-Columbia mineral belt include 100,000 tons grading 1.74 percent copper, 0.18 ounces gold per ton. and 1.6 ounce silver per ton (Kauffman, 1970, p. 4), and 2.7 million tons grading 0.075 ounce gold per ton. Reserves at the Yellowjacket mine are 22,000 ounces of gold in the oxide ore. Exploration is in progress to develop resources in the primary sulfide ore (John Lawrence, U.S. Antimony Corporation, personal communication, February 1997).