Homestake

Mine, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Cu
Ore minerals chalcocite; galena; gold; pyrite; stibnite; tetrahedrite

Geographic location

Quadrangle map, 1:250,000-scale LG
Quadrangle map, 1:63,360-scale A-1
Latitude 65.071
Longitude -147.366
Nearby scientific data Find additional scientific data near this location
Location and accuracy Cobb (1972, MF-413), loc. 45; NW1/4SW1/4 sec. 21, T. 3 N., R. 2 E., of the Fairbanks Meridian. This mine is at the head of Wolf Creek, adjacent to the cabins marked on the Livengood (A-1) quadrangle map.

Geologic setting

Geologic description

In 1908, the Homestake Tunnel site, which is currently known as the Nordale adit, was staked (Times Publishing Company, 1912). Five gold-bearing, quartz-rich shear zones were located on the surface above the intended site of the Homestake adit (Smith, 1913; B 525). Stibnite, pyrite and chalcopyrite were noted in a bulk sample. This material was extracted from a 3-inch-wide 'stringer' zone encountered in the adit approximately 315 feet from the portal. The shear strikes east-west and dips 45 S (Brooks, 1914). Two drifts were driven along the 45 S, east-west trend of mineralization along this main stringer zone known as the Nordale shear (Times Publishing Company, 1912).
By mid-1913, the eastern drift on the Nordale shear was 300 feet long and two stopes had been mined out. The shear zone in the east drift is discontinuous along strike, and in both dip directions, although the mineralized shear zone appears to have the same orientation as barren portions of the shear zone. An 8-foot-deep winze on the east drift ore shoot indicated that the mineralization pinched out at depth and extended for a distance of 12 feet along the dip slope. The ore shoot extends along the east drift floor for 160 feet from a point 90 feet east of the main adit. The eastern 50 feet of the east drift was barren. Approximately 135 feet east of the 315-foot station in the main adit, a 150-foot raise was driven on the Nordale shear which confirmed the presence of the shear zone to the surface. At a point 30 feet up-dip from the east drift, the raise intersected 10 dip-feet of mineralized shear zone which was stoped out over a 100-foot length. The upper ore shoot has a horizontal pitch and is 3 to 12 inches thick and averages 9 inches thick (Brooks, 1914). The upper portion of the ore shoot is truncated by a horizontal fault of unknown displacement. Barren white quartz veins in the metamorphic country rock commonly increase in abundance near higher grade portions of the shear zone. At least two phases of mineralization are recognized in the east-drift stopes. Early quartz-rich lenses in the country rock are cut by later mineralized quartz veinlets in the shear zone.
At 600 feet from the Homestake adit portal, another shear zone trends N 60 W and dips 45 S. The quartz-rich portions of the shear average 1 foot in width, but pinch and swell along strike. Mineralization consisted of poly-phase quartz containing free gold, stibnite, pyrite, chalcocite and copper carbonates. Total sulfide content is low. Bladed chalcocite associated with higher gold values is described by Brooks (1914) but probably is jamesonite or boulangerite (Freeman, 1992).
Development of the Nordale shear in the east drift of the Homestake adit in 1916 discovered another ore shoot in a raise approximately 100 feet up-dip from the east drift. The raise was driven approximately 235 feet east of the main Homestake adit (Brooks, 1918; Stewart, 1922). The new ore shoot was similar in character to previously encountered shoots in the Homestake workings and strikes N 68 E and dips 40 SW. The horizontal fault which truncates the upper ore shoot in the adjacent raise was also encountered in the new raise where it had a strike of N 60 E with a dip of 30 NW. Gold mineralization was restricted to the quartz-rich portion of the shear zone and was associated with stibnite and minor pyrite and chalcocite.
Metallurgical work conducted on material from the Nordale shear zone revealed the presence of variable amounts of scheelite commonly associated with stibnite and high silver values (Hall, 1940). The high gold and silver content of the Nordale shear zone was investigated with a series of tests which indicated most of the gold was contained in quartz rather than sulfides, and sulfides were liberated at approximately 100 mesh. The highest gold and silver values were found in the -200 mesh size fraction. The silver-bearing mineral is argentiferous tetrahedrite (Metz, 1987).
Plans to continue development and produce antimony from discrete stibnite pods in the mine were abandoned when assays indicated unacceptably high lead contents in the ore (Joesting, 1943). Analytical results from a dump sample of stibnite taken in 1942 returned a grade of 45.64% antimony (Killeen and Mertie, 1951).
A ten foot thick sequence of massive sulfide known as the Truck system was intersected in drilling beneath the Nordale adit. This mineralization was 10 feet thick and graded 0.04 ounces of gold per ton, 12 ounces of silver per ton, 6.24% lead and 7.31% zinc (Porterfield and Croff, 1986). Mineralization was hosted by chloritic and manganiferous quartzite, graphitic schist and exhalite of the middle Cleary Sequence.
Samples from the Nordale adit dump contained highly anomalous gold, silver, arsenic and antimony hosted by chloritic and manganiferous quartzite, graphitic schist and exhalite of the middle Cleary Sequence (Fairbanks Exploration Inc., unpublished report, 1986). Samples from the dump averaged 0.030 ounces of gold per ton and 0.25 ounces of silver per ton, with anomalous arsenic and antimony; visible galena, sphalerite and rare chalcopyrite are also present.
In early May, 1911, 1,300 tons of ore from the Homestake adit returned average grades of $470 per ton in gold (22.7 ounces of gold per ton). Smith (1913) reported that this bulk sample contained $308 per ton in free gold (14.9 ounces of gold per ton) with the remainder of the values being in gold and high silver in concentrates not recoverable by amalgamation. Work at the Homestake adit continued in 1914, and 30 to 50 tons of ore were mined that contained approximately $100 of gold per ton (4.8 ounces of gold per ton) (Brooks, 1915; Stewart, 1915). Approximately 50 tons of ore was mined from the Homestake mine in 1915 and returned an average value of $100 per ton in gold (4.8 ounces of gold per ton) (Smith, 1917; BMB 142). A total of 80 tons of ore of unknown grade was mined from the Homestake adit in 1916 (Mertie, 1918).
Gold production from the Homestake adit was estimated at $60,000 (about 2,900 ounces) through 1931 (Hill, 1933). A total of 54 tons of ore from the Nordale shear were milled at the McCarty mill and returned an average grade of $52 of gold per ton (1.5 ounces of gold per ton) (Reed, 1939).
Geologic map unit (-147.368448575375, 65.070577926584)
Mineral deposit model Sulfide and gold-bearing, quartz shear zones in schist.
Alteration of deposit Quartz and sericite; throughout the vein, vugs and veinlets contain limonite and oxidation products of vein minerals.

Production and reserves

Workings or exploration
In 1908, the Homestake tunnel, which currently is known as the Nordale adit, was staked (Times Publishing Company, 1912). Five, gold-bearing quartz-rich shear zones were located on the surface above the intended site of the Homestake adit (Smith, 1913; B 525). Between October, 1908 and May 1911, the adit was driven approximately 315 feet. Work continued in the Homestake adit until November, 1912, when the adit was approximately 680 feet long. Work concentrated on the main stringer zone, now known as the Nordale shear, where two drifts were driven along the 45 degree south-dipping, east-west trend of mineralization. The western drift was 50 feet in length and the eastern drift had been driven 100 feet when mineralization was cut off by a fault (Times Publishing Company, 1912). By mid-1913, the eastern drift on the Nordale shear was 300 feet long and two stopes had been mined out. Approximately 135 feet east of the 315-foot station in the main adit, a 150-foot raise was driven on the Nordale shear which confirmed the presence of the shear zone to the surface.
By mid-1913, the Homestake adit had been extended to 750 feet in length and had intercepted three mineralized shear zones. In 1938, the Homestake adit was re-opened and 200 feet of drift driven on the Nordale shear zone west of the main adit (Reed, 1939). A 50-foot shaft was sunk on this shear and a 65-foot exploration adit driven on the nearby Wolf shear. By 1940, Hall (1940) reported the east drift of the Homestake adit to be 700 feet long with little or no cross-faults along this length. Development efforts at the Homestake adit were terminated by War Production Board Limitation Order L208 in 1942.
In 1982, Placid Oil Company (POC) began rehabilitation of the Homestake adit, now known as the Nordale adit (Porterfield and Croff, 1986). Efforts in 1982 consisted of rehabilitation of 950 feet of old adit and completion of 1,561 feet of new adit and drift. Of this total, 600 feet of drift was driven west of the main adit to access the Christina shear zone and 250 feet of cross-cut was driven to access the shear zone along strike. In 1983, POC drove an additional 163 feet of drift east of the main adit and 103 feet of new drift west of the main adit. POC also completed 700 feet of underground diamond drilling in 7, BQ (1.433 inch) wireline holes (Porterfield and Croff, 1986). Placid Oil did not conduct any work on the Nordale shear zone and the east and west drifts remained caved.
In the spring of 1986, the portal of the Nordale adit caved and the adit has remained inaccessible since that time. The prospect was examined in 1986 by Fairbanks Exploration Inc. and grab samples were collected from a small portion of the Nordale adit dump.
Indication of production Yes; medium
Production notes
In early May, 1911, 1,300 tons of ore from the Homestake adit returned average grades of $470 per ton in gold (22.7 ounces of gold per ton). Smith (1913, B 525) reported that this bulk sample contained $308 per ton in free gold (14.9 ounces of gold per ton) with the remainder of the values being in gold and high silver in concentrates not recoverable by amalgamation. Work at the Homestake adit continued in 1914, and 30 to 50 tons of ore were produced that contained approximately $100 per ton in gold (4.8 ounces of gold per ton) (Brooks, 1915; Stewart, 1915). Approximately 50 tons of ore was mined from the Homestake mine in 1915 and returned an average value of $100 per ton in gold (4.8 ounces of gold per ton) (Smith, 1917; BMB 142). A total of 80 tons of ore of unknown grade was mined from the Homestake adit in 1916 (Mertie, 1918).
Gold production from the Homestake adit was estimated at $60,000 (2,900 ounces) through 1931 (Hill, 1933). A total of 54 tons of ore from the Nordale shear were milled at the McCarty mill and returned an average grade of $52 per ton (1.5 ounces of gold per ton) (Reed, 1939).

References

MRDS Number A015449

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.)
Hall, D., 1940, Geology and dressing of the gold and silver ore of the Homestake Mine, Wolf Creek, Fairbanks District, Alaska: University of Alaska, Fairbanks, B.S. thesis, 43 p.
Metz, P.A., 1987, Ore mineralogy and gold grain size distribution in the gold-silver-arsenic-antimony-tungsten mineralization of the Fairbanks mining district, Alaska: The Metallurgical Society, Process Mineralogy, v. 7, 18 p.
Porterfield, J. and Croff, C., 1986, Summary report for the Cleary Project, Fairbanks district, Alaska - 1985: Placid Oil Company report, 36 p.
Smith, S.S., 1917, The mining industry in the territory of Alaska during the calendar year 1915: U.S. Bureau of Mines Bulletin 142, 66 p.
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)
Last report date 5/4/1999