McCarty

Mine, Active

Alternative names

American Eagle

Commodities and mineralogy

Main commodities Au; Sb
Other commodities Ag; As; Pb; Zn
Ore minerals arsenopyrite; gold; jamesonite; pyrite; sphalerite; stibnite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale LG
Quadrangle map, 1:63,360-scale A-1
Latitude 65.0646
Longitude -147.3536
Nearby scientific data Find additional scientific data near this location
Location and accuracy The McCarty Mine is labeled on the Livengood A-1 quadrangle; it is in the headwaters of Fairbanks Creek at an elevation of about 1970 feet; it is in the NW1/4NE1/4 section 28, T. 3 N., R. 2 E., of the Fairbanks Meridian.

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).
The McCarty Mine, also known as the American Eagle Mine, was one of the most productive gold mines in the district. The American Eagle shear zone was mined through the American Eagle adit and American Eagle shaft. Although the old stamp mill and head-frame of the McCarty Mine were still standing in 1992, the underground workings of the mine were inaccessible (Freeman, 1992).
The rocks in the area are mainly quartz-mica schist, but quartzite and calcareous schist also are present locally. The wall rocks adjacent to the vein are sericitized (Joesting, 1941).
Most ore came from the American Eagle vein, which is from one to three feet thick, strikes N60W and dips 55-60SW; it consists of coarsely crystalline quartz with free gold and small amounts jamesonite, stibnite, arsenopyrite and sphalerite (Joesting, 1941, p. 3). Large kidneys of high-grade stibnite with up to 61 percent antimony, occur in segments of the vein (Joesting, 1941, p. 3).
During the winter of 1914-1915, a 450-foot adit was driven on the American Eagle claim and significant of ore were mined during the summer of 1915 (Stewart, 1915). By 1915, the American Eagle shaft had been sunk to a depth of 107 feet (Brooks, 1915). In 1936, United States Smelting Refining and Mining Company (USSR&M) began drifting along the 135-foot level through the American Eagle shaft (Smith, 1939). Extensive development continued in 1938 but the results of sampling were not encouraging (Smith, 1939). In 1938, USSR&M sank 120 feet of shaft in the American Eagle vein, shaft, put in 625 feet of raise, and drove 1,816 feet of drift, crosscuts and adit (Reed, 1939). Mining continued in 1939 when USSR&M completed 465 feet of drifts and crosscuts and nearly 400 feet of raises. The ore was treated in a 2-stamp Nissen mill and the tailings were impounded for later upgrading (Smith, 1941). Mining continued in 1940 when 639 feet of drifts and crosscuts were driven as well as 545 feet of raises. The American Eagle shaft was deepened to 250 feet giving access to over a mile of drifts and 1,750 feet of raises, with workings on the 28-, 135-and 235-foot levels (Smith, 1942). Mining continued in 1941 when USSR&M sank a 65-foot winze from the east end of the 235 level. USSR&M maintained the properties until 1958 but no further mining was reported (Porterfield and Croff, 1986). The stamp mill at the McCarty Mine also processed ore from the Henry Ford group of claims which included ore from both the McCarty vein (LG150) and the Henry Ford vein (LG153).
In 1984, Placid Oil Company drilled 6,137 feet in 23 diamond core holes. Based on this work, the deposit was estimated to have 15,000 tons of reserves with an average grade of 0.80 ounces of gold per ton. During this period Alaska Mineral Services also constructed a small carbon-in-pulp leach plant (the Haskins mill) at the McCarty Mine to treat mill tailings from the McCarty mine and the Hi Yu mine.
In 1986, Fairbanks Exploration Inc. collected bulk samples from the mill tailings and waste dump. The average gold grades of the mill tailings was 0.091 to 0.168 ounces of gold per ton. However, a portion of the samples was taken from mill tailings which had been re-treated in a cyanide mill erected on the prospect in the early 1980s. Therefore, the results are not an accurate estimate of gold grades for the bulk of the American Eagle mill tailings. Channel sampling of American Eagle mill tailings in 1987 indicated an average grade of 0.123 ounces of gold per ton and 0.74 ounces of silver per ton (Fairbanks Exploration Inc., unpublished report, 1987). The mill tailings were estimated to contain about 3,000 tons of material in 1987. At least some of these mill tailings were processed by Tri-Con Mining after mid-August 1988. The average gold grade of the mine dumps of the McCarty Mine range from 0.132 to 0.158 ounces of gold per ton (Fairbanks Exploration Inc., unpublished report, 1988).
Through 1917, the American Eagle vein produced approximately 967 ounces of gold with an average grade of about one ounce of gold per ton (J. McCarty, unpublished report, 1932). Rock mined during development in 1929 and 1930 produced 1,274 ounces of gold from 1,225 tons of ore (J. McCarty, unpublished report, 1932; Hill, 1931). During 1931, approximately 34 ounces of gold was recovered from 27 tons of material excavated from a surface cut on the American Eagle shear zone (J. McCarty, unpublished report, 1932). Smith (1933b) reported that the McCarty mine was the largest producer in the Fairbanks Creek basin in 1931. A total of 600 tons of ore was milled in 1938 at a rate of 240 tons per month (Reed, 1939). The McCarty mine ceased operations in 1942 due to War Production Board Limitation Order L208. However, about 15 tons of high-grade stibnite ore was shipped from the prospect in 1942. This ore contained 60.66 percent antimony (Joesting, 1942). An additional 5 tons of stibnite ore with 45 percent antimony was shipped from the mine in 1942 (Joesting, 1943; Killeen and Mertie, 1951).
Estimates of the total mine production vary from 26,800 ounces of gold from 16,750 tons of ore (Porterfield and Croff, 1986), to 60,000 ounces of gold (Metz and others ,1987).
Geologic map unit (-147.356047764916, 65.0641780917854)
Mineral deposit model Gold-stibnite vein.
Age of mineralization Probably about 90 Ma based on analogy with similar gold deposits nearby.
Alteration of deposit Sericitization of country rock.

Production and reserves

Workings or exploration
The McCarty Mine, also known as the American Eagle Mine, was one of the most productive gold mines in the district. The American Eagle shear zone was mined through the American Eagle adit and American Eagle shaft. Although the old stamp mill and head-frame of the McCarty Mine were still standing in 1992, the underground workings of the mine were inaccessible (Freeman, 1992).
During the winter of 1914-1915, a 450-foot adit was driven on the American Eagle claim and significant of ore were mined during the summer of 1915 (Stewart, 1915). By 1915, the American Eagle shaft had been sunk to a depth of 107 feet (Brooks, 1915). In 1936, United States Smelting Refining and Mining Company (USSR&M) began drifting along the 135-foot level through the American Eagle shaft (Smith, 1939). Extensive development continued in 1938 but the results of sampling were not encouraging (Smith, 1939). In 1938, USSR&M sank 120 feet of shaft in the American Eagle vein, shaft, put in 625 feet of raise, and drove 1,816 feet of drift, crosscuts and adit (Reed, 1939). Mining continued in 1939 when USSR&M completed 465 feet of drifts and crosscuts and nearly 400 feet of raises. The ore was treated in a 2-stamp Nissen mill and the tailings were impounded for later upgrading (Smith, 1941). Mining continued in 1940 when 639 feet of drifts and crosscuts were driven as well as 545 feet of raises. The American Eagle shaft was deepened to 250 feet giving access to over a mile of drifts and 1,750 feet of raises, with workings on the 28-, 135-and 235-foot levels (Smith, 1942). Mining continued in 1941 when USSR&M sank a 65-foot winze from the east end of the 235 level. USSR&M maintained the properties until 1958 but no further mining was reported (Porterfield and Croff, 1986). The stamp mill at the McCarty Mine also processed ore from the Henry Ford group of claims which included ore from both the McCarty vein (LG150) and the Henry Ford vein (LG153).
In 1984, Placid Oil Company drilled 6,137 feet in 23 diamond core holes. During this period Alaska Mineral Services also constructed a small carbon-in-pulp leach plant (the Haskins mill) at the McCarty Mine to treat mill tailings from the McCarty mine and the Hi Yu mine.
In 1986, Fairbanks Exploration Inc. collected bulk samples from the mill tailings and waste dump. At least some of these mill tailings were processed by Tri-Con Mining after mid-August 1988.
Indication of production Yes; small
Reserve estimates
In 1984, Placid Oil Company drilled 6,137 feet in 23 diamond-core holes. Based on this work, the deposit was estimated to have 15,000 tons of reserves with an average grade of 0.80 ounces of gold per ton.
In 1986, Fairbanks Exploration Inc. collected bulk samples from the mill tailings and waste dumps. The mill tailings were estimated to contain about 3,000 tons of material in 1987. At least some of this material was processed by Tri-Con Mining after mid-August 1988.
Production notes
Total production from the American Eagle shear through 1917 was approximately 967 ounces of gold with an average grade of about one ounce of gold per ton (J. McCarty, unpublished report, 1932). Milling of development material in 1929 and 1930 produced 1,274 ounces of gold from 1,225 tons of ore, averaging 1.04 ounces of gold per ton (J. McCarty, unpublished report, 1932; Hill, 1931). During 1931, approximately 34 ounces of gold was recovered from 27 tons of material excavated from a surface cut on the American Eagle shear zone (J. McCarty, unpublished report, 1932). Smith (1933, B 844) reported that the McCarty mine was the largest producer in the Fairbanks Creek basin in 1931. A total of 600 tons of ore from the American Eagle workings was milled in 1938 at a rate of 240 tons per month (Reed, 1939).
The McCarty mine ceased operations in 1942 due to War Production Board Limitation Order L208. However, about 15 tons of high-grade stibnite ore was shipped from the prospect in 1942. This ore graded 60.66 percent antimony (Joesting, 1942). In addition, about 5 tons of stibnite ore grading 45 percent antimony was also shipped from the American Eagle mine in 1942 (Joesting, 1943; Killeen and Mertie, 1943).
Total production from the McCarty mine workings (American Eagle, Henry Ford and McCarty shear zones) is estimated at 26,800 ounces from 16,750 tons of ore, averaging 1.6 ounces of gold per ton (Porterfield and Croff, 1986). However, Metz and others (1987) estimate production from the McCarty mine was approximately 60,000 ounces of gold.

References

MRDS Number A015451

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.)
Freeman, C.J., 2008, Executive summary report for the Golden Summit project, Fairbanks Mining District, Alaska: Unpublished Technical Report for Freegold Ventures Ltd., 112 p. (posted on www.sedar.com, March 31, 2008).
Metz, P.A., Freeman, C.J., and Calvin, J.S., 1987, Bulk mineable vein-type and disseminated gold mineralization of the Fairbanks mining district, Alaska: Australasian Institute of Mining and Metallurgy, Pacific Rim Congress 87, Proceedings, p. 333-342.
Pilgrim, E.R., 1933, Progress of lode mining in interior Alaska, 1932: Alaska Territorial Department of Mines Miscellaneous Report 194-4, 11 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.
Reporters C.J. Freeman, J.R. Guidetti Schaefer (Avalon Development Corporation); D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008