Blue Lead; Blue Lead Extension Mines, Goodpaster Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Blue Lead; Blue Lead Extension Mines	Group of Mines
Goodpaster Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

Location: The Blue Lead and Blue Lead Extension mines are situated on the ridge of Black Mountain near the divide that separates the headwaters of Johnson Creek, a tributary of Tibbs Creek (BD040), and Summitt Creek, a tributary of Boulder Creek (BD004). The mines are located at NW1/4NW1/4 section 33, T. 6 S., R. 17 E., of the Fairbanks Meridian, 54 miles north of Delta Junction. A winter trail from the South Fork of the Goodpaster River provides access up Divide Creek to the mine. The Blue Lead and Blue Lead Extension mines are located near an ore processing mill. The mine shaft entrances and ore processing mill were still accessible in 1970 (Thomas, 1970). There are numerous surface workings at and surrounding the site. It is locality 5 of Cobb and Eberlein (1980) who summarized relevant references under the name 'Blue Lead'.
Geology: The area is characterized by rounded hills and flat topped ridges (Thomas, 1970). The most prominent ridge is Black Mountain, which trends about 12 miles in a northerly direction and is underlain by Cretaceous granodiorite (Weber and others, 1978). Several creeks flow westward from Black Mountain in steep, parallel, v-shaped valleys to form the headwaters of Tibbs Creek. Bordering Black Mountain to the west is a combination of augen gneiss, gneissic schist, and schist. There is intense shearing and faulting in the contact between the metamorphic and intrusive rocks. This shearing is observed in the underground workings, and at the surface as pronounced saddle-like depressions across the spurs separating the westward-flowing tributaries of Tibbs Creek. This shear zone trends roughly N15E and dips 65 degrees NW. The lode deposits in the area are gold-bearing quartz veins in the shear zone. Most of the veining occurs in the shear zone, although some is found in the intrusive rocks. The quartz veins contain gold and a variable combination of sulfides, including arsenopyrite, covellite, digenite, jamesonite, pyrite, and stibnite. Typically, gold content decreases as sulfides increase. Veins are commonly 2 to 3 feet in width; some are as wide as 8 feet (Thomas, 1970). When gold is present, it is usually extremely fine grained. However, veins at the Grizzly Bear mine (BD018) contain relatively coarse gold, which is easily visible in hand specimen. The Blue Lead mine is centered on a 2.5 foot wide quartz vein containing jamesonite and minor pyrite (Menzie and Foster, 1979). Based on underground workings, the vein is relatively flat lying or dips to the north (Reed, 1937). Thomas (1970) assayed a grab sample from the mill concentration plates that contained 4.58 ounces/ton Au, and 6.50 ounces/ton Ag. Foster and others (1978) recorded an emmision spectroscopy analysis from the Blue Lead Mine: sample 74WR-186b contained 10,000 ppm As, 10 ppm B, 50 ppm Ba, 1 ppm Cr, 100 ppm Se, 5 ppm Sr, 15 ppm Zr, and 1 ppm Au. Glover (1950) reported a range in gold fineness of 724.4 to 773.7 for the Blue Lead mine. The Goodpaster region was first explored for placer gold in 1915. In the early 1930's, gold-bearing quartz veins were discovered in the upper Tibbs Creek area. By the winter of 1936, the first underground workings were being installed. The original base camp was on Summit Creek. A 450-foot tunnel was driven following a small vein, termed the Blue Lead Extension. After disappointing results, the work was stopped. In the summer of 1936, five men drove a 300-foot tunnel at the outcrop of the Blue Lead vein (Reed, 1937). During the winter of 1937, a 300-foot tunnel was driven at the Grizzly Bear mine (BD018) and a 50-ton mill was constructed. In the summer of 1938, the mill was moved to the Blue Lead mine and operated for a year and a half until the fall of 1939 (Joesting, 1938). The Blue Lead and Blue Lead Extension have approximately 775 feet of underground workings. There was limited exploration in the 1970's. The mill was still on site and the mine shaft openings were accessible in 1970, but blocked by ice (Thomas, 1970). It is reported that the Blue Lead mine produced 132 ounces of gold and 25 ounces of silver from approximately 150 tons of ore (Thomas, 1970). Gold recovery from the Blue Lead Extension was negligible (Reed, 1937).
Workings: The Goodpaster region was first explored for placer gold in 1915. In the early 1930's, gold-bearing quartz veins were discovered in the upper Tibbs Creek area. By the winter of 1936, the first underground workings were being installed. The original base camp was on Summit Creek. A 450 foot tunnel was driven following a small vein, termed the Blue Lead Extension. After disappointing results, the work was stopped. In the summer of 1936, five men drove a 300-foot tunnel at the outcrop of the Blue Lead vein (Reed, 1937). During the winter of 1937, a 300-foot tunnel was driven at the Grizzly Bear mine (BD018) and a 50-ton mill was constructed. In the summer of 1938, the mill was moved to the Blue Lead mine and operated for a year and a half until the fall of 1939 (Joesting, 1938). The Blue Lead and Blue Lead Extension have approximately 775 feet of underground workings. There was limited exploration in the 1970's. The mill was still on site and the mine shaft openings were accessible in 1970, but blocked by ice (Thomas, 1970).
Age: Postdates Cretaceous intrusion
Production: It is reported that the Blue Lead mine produced 132 ounces of gold and 25 ounces of silver from approximately 150 tons of ore (Thomas, 1970). Gold recovery from the Blue Lead Extension was negligible (Reed, 1937).

Commodities (Major) - Au; (Minor) - Ag, Cu, Pb, Sb
Development Status: Yes; small
Deposit Model: Shear-hosted, magmatic-hydrothermal vein

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Link to USGS - Alaska:	BD003

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References