Alaska; Gladstone; Jupiter-Mars; Grace E#2? Mine, Fairbanks Mining District, Fairbanks North Star Borough, Alaska, USAi

Regional Level Types
Alaska; Gladstone; Jupiter-Mars; Grace E#2? Mine	Mine
Fairbanks Mining District	Mining District
Fairbanks North Star Borough	Borough
Alaska	State
USA	Country

Location: Cobb (1972, MF-413), loc. 42; NE1/4SW1/4 sec. 20, T. 3 N., R. 2 S., of the Fairbanks Meridian. The mine is on the hillside east of Chatham Creek at an elevation of about 1,700 feet. Accuracy is within 2,000 feet.
Geology: The Alaska prospect originally was known by the name Jupiter Mars prospect after several claims and fractions bearing that name. The prospect was discovered prior to 1910 by which time the Jupiter Mars claim was being explored by a 70-foot adit and a 50-foot crosscut (Brooks, 1911). Work continued in 1911 and by 1912, seven or eight claims in the area had been purchased by the Jupiter-Mars Consolidated Gold Company (Brooks, 1912; Smith, 1913; B 525). This company owned the Shamrock, Emerald, Gladstone, Richman, Henchman, Chatham, Jupiter, Mars, and Jupiter Mars Extensions Nos. 1, 2, 3 and 4 (Times Publishing Company, 1912). Work was concentrated in two short adits on the Goldstone claim. These adits intersected a northwest-striking, shallowly south-dipping shear zone from which several tons of custom milled ore returned values of about $30 per ton (1.45 ounces of gold per ton) (Smith, 1913; B 525, p. 175). Sulfides make up only a small proportion of the shear zone. Gold is associated with white-quartz vein material (Smith, 1913; B 525, p 175). The shear zone is cut off in the northern tunnel by frozen fluvial gravels indicating the material in which the tunnel is driven may be part of large slump block. A 66-foot deep shaft had been sunk to the east of the adits by 1912 to prospect along the shear zone (Smith, 1913; B 525). Work continued in 1913 when the shaft was deepened to 125 feet and 112 feet of drift were driven from the shaft (Chapin, 1914, p. 337). The area was restaked as the Alaska, Alaska #2 and Alaska #3 claims by Fred M. Wackwitz on July 1, 1931 (Hill, 1933). The prospect subsequently became known as the Alaska group and was first prospected with large ditches cut by ground sluicing to remove surface debris. A scorodite-stained quartz-bearing shear zone oriented east-west with a 30 degree north dip, was exposed in this manner; it measured 3 to 5 feet wide and averaged $0.43 per ton (0.02 ounces of gold per ton). In 1979, Placid Oil began surface trenching, diamond core drilling and geochemical sampling of the shear zones which had been discovered previously. Between 1979 and 1986, Placid Oil drilled 5,137 feet of diamond core and cut several thousand feet of dozer trenches on the prospect, primarily on the Christina shear zone north of the adits and shaft previously driven on the prospect (Porterfield and Croff, 1986). In 1986, Placid Oil Company dropped its lease on the prospect. The trenches on the Alaska prospect were reclaimed by Placid Oil in 1985; however, sidewall exposures of gold quartz and sulfide shear zones remain and served as sample sites for field work conducted by Fairbanks Exploration Inc. in 1987. Samples collected from the prospect contained anomalous gold (70 to 1600 ppb), silver (5.5 ppm to 179.9 ounces of silver per ton), arsenic (+1000 ppm) and antimony (330 to +10000 ppm) hosted in white quartz and quartz-sericite, rhyolite tuff, stained by scorodite, iron oxide and antimony oxide (Fairbanks Exploration Inc., unpublished report, 1987). The core of the Jupiter Mars shear zone was exposed in trench walls where it contained 1 to 6 inch wide quartz stringers which were broken and recemented by later quartz. The shear strikes N 80 E and dips 55 SE. Host rocks in the trench exposures and on the dumps of one of the old adits were highly oxidized rhyolitic tuff with pervasive scorodite and iron-oxide stains. No other work has been conducted on the Alaska prospect and all underground workings are now inaccessible.
Workings: A 70-foot adit tunnel and a 50-foot crosscut were completed in 1910 on the Jupiter-Mars property (Brooks, 1911, p. 34). Two tunnels were dug on a flat-lying vein that dips south and shaft was sunk 125 feet to a vein (Chapin, 1914, p. 337). All of the old workings caved by 1931, and newer workings consisted mainly of trenches and pits (Hill, 1933, p. 99-100).
Alteration: Sericite, scorodite, iron oxide and antimony oxide.
Production: Chapin (1914), reported 'some production', however the exact amount is unknown.

Commodities (Major) - Au
Development Status: Yes; small
Deposit Model: Gold, silver, arsenic and antimony minerals in quartz-bearing shear zones and q

Other Databases

Link to USGS - Alaska:	LG141

Other Regions, Features and Areas containing this locality

References