Pennsylvania

Mine, Active

Commodities and mineralogy

Main commodities Au
Other commodities Sb
Ore minerals gold; stibnite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale LG
Quadrangle map, 1:63,360-scale A-1
Latitude 65.0686
Longitude -147.3575
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Pennsylvania Mine is on the ridge east of the head of Wolf Creek; it is in the SE1/4SW1/4 sec. 21, T. 3 N., R. 2 E., of the Fairbanks Meridian. The location is for the northwest shaft which is on the divide between the head of Wolf Creek and Fairbanks Creek.

Geologic setting

Geologic description

Note: As of 2008, this site and several others in the vicinity are being explored as a single entity by Freegold Ventures Inc. (Freeman, 2008) Considerable new mineralization has been discovered that indicates this is part of a larger mineralized system that is described as a separate ARDF site (LG206).
Free gold occurs at the Pennsylvania Mine associated with antimony oxides in white quartz. The mineralization is along a shear zone that strikes N76W and dips 56SW (Smith, 1913). The high grade portion of the shear zone average 12 to 15 inches thick.
The Pennsylvania claim was staked in October 1911 by Lawrence J. McCarty and soon became part of the McCarty group of claims which included the Pennsylvania, Willie, Dorothy, Marie, Kentucky and Freegold claims (Times Publishing Company, 1912).
In late 1911, an 8.5-ton sample of material from the Pennsylvania Mine averaged $100 gold per ton (4.8 ounces of gold per ton). A second lot of ore was custom milled in early 1912 and averaged $52 gold per ton (2.5 ounces of gold per ton). By 1913, the Pennsylvania shaft was 146 feet deep, and between 1922 and 1931, the west drift on the 50-foot level was 70 feet long and stoped to the surface. This work produced approximately $10,000 worth of gold (484 ounces) (Hill, 1933).
The Pennsylvania mine was examined in 1942 as a possible source of antimony. Samples from a one-half ton stockpile of oxidized stibnite near the shaft had an average grade of 57.01 percent antimony but the mine did not possess sufficient quantity of this material to warrant additional exploration or development (Killeen and Mertie, 1951).
Geologic map unit (-147.35994823481, 65.0681780746381)
Mineral deposit model Gold-stibnite-quartz veins.
Age of mineralization Probably about 90 Ma based on analogy with similar gold deposits nearby.
Alteration of deposit Stibnite altered to antimony oxides.

Production and reserves

Workings or exploration By late 1912, the Pennsylvania shaft was 140 feet. deep. Drifts were driven 20 feet to the northwest and southeast on the 140-foot level. At the 50- foot level, drifts extended 50 feet northwest and 50 feet southeast with a raise connected to the surface from the southeast drift (Times Publishing Company, 1912). The ore was hoisted using a Little Giant steam hoist and was shipped to the company mill constructed on upper Fairbanks Creek by L.J. McCarty and Emil C. Fursteneau. This mill began operation in September, 1912 and consisted of a Little Giant #3 roll mill which fed minus-40-mesh pulp over amalgamation plates (Times Publishing Company, 1912). The tailings were not impounded. The mill had a capacity of 8 to 20 tons of ore per day (Smith, 1913). By mid-1913, the Pennsylvania shaft was 146 feet deep (Chapin, 1914). Some time between 1922 and 1931, the western drift on the 50-foot-level was extended to a length of 70 feet and stoped to the surface. The shaft and workings were flooded in 1931.
Indication of production Yes; small
Production notes In late 1911, an 8.5 ton sample of material from the Pennsylvania Mine averaged $100 per ton in gold (4.8 ounces of gold per ton). A second lot of Pennsylvania ore was custom milled in early 1912 and averaged $52 per ton (2.5 ounces of gold per ton). The mine was not in production in 1913. The mine was examined in 1922 by Stewart (1922) and Davis (1922) but was not in production at that time. Some time between 1922 and 1931, the western drift on the 50-foot level was extended to a length of 70 feet and stoped to the surface; this work produced about $10,000 in of gold (484 ounces) (Hill, 1933).

References

References

Freeman, C.J., 1992, 1991 Golden Summit project final report, volume 2: Historical summary of lode mines and prospects in the Golden Summit project area, Alaska: Avalon Development Corp., 159 p. (Report held by Freegold Recovery Inc. USA, Vancouver, British Columbia.)
Times Publishing Company, 1912, Tanana Magazine, Quartz Edition: Fairbanks, Alaska, Times Publishing Company, 76 p.
Reporters C.J. Freeman, J.R. Guidetti Schaefer (Avalon Development Corporation); D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008