Perseverance; Alaska-Juneau; Alaska Gastineau; South Orebody Mine, Juneau District, Juneau Borough, Alaska, USA

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Location: This mine is at an elevation of 1,700 feet, at the head of Icy Gulch. It is 3 miles southeast of Mt. Juneau and 1/2 mile north of Gastineau Peak, in the NE1/4SW1/4 section 20, T. 41 S., R. 68 E. of the Copper River Meridian. The location is accurate. Descriptions of the Alaska-Juneau mine (JU165) commonly include the Perseverance Mine.
Geology: The Perseverance Mine is often considered the Perseverance orebody of the Alaska-Juneau mine (JU165). The Perseverance Mine was discovered by Joe Juneau and Richard Harris in 1880 and the mine was extracting 8,000 tons of ore per day by 1917. The mine was developed by 2 major crosscuts, the Alexander crosscut (JU154) completed in 1905, and the Sheep Creek Tunnel (JU177) completed in 1914. The mine was acquired by the Alaska-Juneau Mining Company in 1933 and connected underground with the Alaska Juneau Mine (JU165) in 1935. The mine operated from 1886 to 1943 and produced about 70 percent of the total ore mined by the Alaska Juneau Mining Company. The total production from the Perseverance Mine was over 12 million tons of ore that yielded approximately 500,900 ounces of gold and over 482,000 ounces of silver. The deposit was mined by modified block-caving and hand-sorting. There are 26 miles of underground workings on 10 levels in the Perseverance Mine which, combined with the Alaska-Juneau Mine, totals nearly 120 miles of underground workings. During 1986-1988 Echo Bay Mines renovated the Sheep Creek Tunnel (JU177), completed a 2,000 foot decline to the AJ 4 level, and drove 1,100 feet of new workings in the Perseverance Mine (Cobb, 1978 [OFR 78-374]; Redman and others, 1989). Approximately 360,000 feet of underground and surface core drilling was completed by Echo Bay Mines in the mine area between 1986 and 1997. Echo Bay Mines Ltd. calculated an indicated and inferred resource for the Alaska-Juneau Mine, which includes the Perseverance orebody, of 89 million tons of ore that contain 0.05 ounce of gold per ton (L. Miller, personal commun., 2001). The Perseverance orebody is part of the Alaska-Juneau's South orebody. The deposit is a system of sulfide-bearing, auriferous, quartz-ankerite veins in the structurally lowest portion of the Perseverance Slate, an Upper Triassic unit of carbonaceous and graphitic quartz-sericite phyllite, schist, and black slate, with minor carbonaceous limestone and numerous sill-like lenses of amphibolite or metagabbro (Miller and others, 1992; Light and others, 1989). The vein system extends for more than 6 kilometers along strike, 700 meters in vertical extent, and is confined to the lowest 100 meters of the Perseverance Slate. The system comprises numerous veins, veinlets, stringers and stockworks; individual veins range from a few centimeters to over 1 meter thick. The veins are 95 percent quartz with subordinate ankerite, pyrrhotite, galena, sphalerite, electrum, arsenopyrite, pyrite, and native gold. Approximately 90 percent of the gold is free-milling (Light and others, 1989; Twenhofel, 1952). The Perseverance Mine is one of the major gold producers in the Juneau Gold Belt. The belt is marked by more than 200 mesothermal, gold-quartz-vein prospects and mines, which produced nearly 7 million ounces of gold (Miller and others, 1994). The structural grain of the belt is defined by a northwest-striking, moderately to steeply northeast-dipping, penetrative foliation that developed between Cretaceous and Eocene time (Miller and others, 1994). Isotopic dates indicate that the auriferous veins in the Juneau Gold Belt formed between 56 and 55 Ma (Miller and others, 1994; Goldfarb and others, 1997).
Workings: The deposit at the Perseverance Mine was discovered by Joe Juneau and Richard Harris in 1880. The mine was developed by 2 major crosscuts, the Alexander crosscut (JU154), completed in 1905, and the Sheep Creek Tunnel (JU177), completed in 1914. The mine was acquired by the Alaska-Juneau Mining Company in 1933 and was connected underground with the Alaska Juneau Mine (JU165) in 1935. The mine operated from 1886 to 1943 and it produced 70 percent of the total ore mined by the Alaska Juneau Mining Company. There are 26 miles of underground workings on 10 levels in the Perseverance Mine which, combined with the Alaska-Juneau Mine, total nearly 120 miles of underground workings. During 1986-1988 Echo Bay Mines renovated the Sheep Creek Tunnel (JU177), completed a 2,000 foot decline to the AJ 4 level, and drove 1,100 feet of new workings in the Perseverance Mine (Cobb, 1978 [OFR 78-374]; Redman and others, 1989). Approximately 360,000 feet of underground and surface core drilling was completed by Echo Bay Mines in the mine area between 1986 and 1997.
Age: Isotopic dates indicate that the auriferous veins in the Juneau Gold Belt formed between 56 and 55 Ma (Miller and others, 1994; Goldfarb and others, 1997).
Alteration: Alternation consists of hydrothermal biotite, ferroan dolomite, and sericite; chlorite and albite partly replace amphibolite( Miller and others, 1992). The alteration has been traced with decreasing intensity as much as 1 kilometer from the Alaska-Juneau mine. Inward from its periphery, magnetite, then ilmenite and magnetite, are replaced by pyrrhotite (Miller and others, 1992; Newberry and Brew, 1987).
Production: The total production from the Perseverance Mine was over 12 million tons of ore that yielded approximately 500,900 ounces of gold and over 482,000 ounces of silver. The deposit was mined by modified block-caving and hand-sorting.
Reserves: Assuming a sublevel caving mining model, Echo Bay Mines Ltd. calculated an indicated and inferred resource for the Alaska-Juneau Mine-- including the Perseverance Mine--of 89 million tons of ore that contain 0.05 ounce of gold per ton.

Commodities (Major) - Ag, Au, Pb; (Minor) - Cu, Zn
Development Status: Yes; large
Deposit Model: Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a)

References

Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Juneau quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-374, 155 p. Gehrels, G.E., McClelland, W.C., Samson, S.D., and Patchett, P.J., 1991, U-Pb geochronology of detrital zircons from a continental margin assemblage in the northern Coast Mountains, southeastern Alaska: Canadian Journal of Earth Sciences, v. 28, no. 8, p.1285-1300. Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190. Light, T.D., Brew, D.A., and Ashley, R.P., 1989, The Alaska-Juneau and Treadwell lode gold systems, southeastern Alaska, in DeWitt, E., Waegli, J., Light, T.D., Brew, D.A., and Ashley, R.P., eds., Gold deposits in metamorphic rocks, Part I: U.S. Geological Survey Bulletin 1857-D, p. D27-D36. Miller, L.D., Barton, C.C., Fredericksen, R.S., and Bressler, J.R., 1992, Structural evolution of the Alaska-Juneau lode gold deposit, southeastern Alaska: Canadian Journal of Earth Sciences, v. 29, p. 865-878. Miller, L.D., Goldfarb, R.J., Gehrels, G,E., and Snee, L.W., 1994, Genetic links among fluid cycling, vein formation, regional deformation, and plutonism in the Juneau gold belt, southeastern Alaska: Geology, v. 22, p. 203-206. Newberry, R.J., and Brew, D.A., 1987, The Alaska-Juneau gold deposit; remobilized syngenetic versus exotic epigenetic origin, 1987, in Hamilton, T.D., and Galloway, J.P., eds., Geologic studies in Alaska by the U.S. Geological Survey during 1986: U.S. Geological Survey Circular 998, p. 128-131. Redman, E.C., Maas, K.M., Kurtak, J.M., and Miller, L.D., 1989, Bureau of Mines Mineral Investigations in the Juneau Mining District, Alaska, 1984-1988, Volume 2--Detailed mine, prospect, and mineral occurrence descriptions, Section D, Juneau Gold Belt Subarea: U.S. Bureau of Mines Special Publication, 424 p. Spencer, A.C., 1906, The Juneau Gold Belt, Alaska: U.S. Geological Survey Bulletin 287, 161 p. Twenhofel, W.S., 1952, Geology of the Alaska-Juneau lode system, Alaska: U.S. Geological Survey Open-File Report 60, 170 p.

Mineral List

Ankerite Arsenopyrite Bismuth Bismuthinite

Chalcopyrite Galena Gold var: Electrum

Joséite Pyrite Pyrrhotite Quartz

Sphalerite Tetrahedrite

14 entries listed. 12 valid minerals.