Perseverance

Mine, Inactive

Alternative names

Alaska-Juneau
Alaska Gastineau
South Orebody

Commodities and mineralogy

Main commodities Ag; Au; Pb
Other commodities Cu; Zn
Ore minerals arsenopyrite; bismuth; bismuthinite; chalcopyrite; electrum; galena; gold; joseite; pyrite; pyrrhotite; sphalerite; tetrahedrite
Gangue minerals ankerite; quartz

Geographic location

Quadrangle map, 1:250,000-scale JU
Quadrangle map, 1:63,360-scale B-2
Latitude 58.299
Longitude -134.3378
Nearby scientific data Find additional scientific data near this location
Location and accuracy 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.

Geologic setting

Geologic description

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 communication, 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).
Geologic map unit (-134.339567198552, 58.2986731428566)
Mineral deposit model Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization 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 of deposit Alteration 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 and reserves

Workings or exploration 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.
Indication of production Yes; large
Reserve estimates 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.
Production notes 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.

References

MRDS Number A012058

References

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.
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.
Reporters J.C. Barnett and L.D. Miller (Juneau, Alaska )
Last report date 12/15/2001