Jualin

Mine, Active

Commodities and mineralogy

Geographic location

Quadrangle map, 1:250,000-scale JU
Quadrangle map, 1:63,360-scale D-4
Latitude 58.8414
Longitude -135.0446
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Jualin Mine is in the Johnson Creek drainage at an elevation of approximately 700 feet, about 2.5 miles south of Lions Head Mountain and 4 miles north of Berners Bay. The mine is marked on the Juneau D-4 topographic map. It is in the NE1/4 section 15, T. 35 S., R. 62 E. of the Copper River Meridian. The location is accurate.

Geologic setting

Geologic description

Note: Beginning in the 1990s, this and other old mines and prospects in the vicinity were consolidated by Coeur-Alaska into a single property (Birak, 2006). They have carried out major new drilling and underground exploration that better defines the mineralization, largely blurs the geologic distinction among the old deposits, and extends the ore bodies greatly. They have developed a coherent modern interpretation of the mineralization as a single deposit which Coeur-Alaska intends to mine as a unit. This deposit is described separately in ARDF as the Jualin (Coeur-Alaska) deposit (JU262). For geologic reference purposes and for their historic value, the pre-Coeur-Alaska data for this and the other old mines and prospects that Coeur-Alaska consolidated are retained in ARDF.
The Jualin deposit was discovered in 1895 and gold recovery began in 1896 when a 10-stamp mill was in operation. In 1914, the first semi-diesel generators in Alaska were installed. Between 1895 and 1929 the mine produced 37,913 ounces of gold from 74,624 tons of ore. The mill recovered 85-90 percent of the gold; 85 percent of the gold was free-milling and the remaining 15 percent was combined with sulfides (Redman and others, 1989).
The Jualin Mine is in Jualin Diorite in a shear zone 400 to 600 feet wide; the shear zone has a strike length of nearly 15,000 feet, and extends from the Jualin Mine area to the Ophir prospect (JU026). The veins in the shear zone generally strike N35W and dip 50-75 NE. The ore bodies pinch and swell along strike; they are as much as 40 feet thick and form ore shoots that exhibit a strong southeast rake (Barnett and others, 1989). Noteworthy veins include the Empire vein, East vein, and the 1, 2, 3, 3E and 4 veins. Production was from relatively high-grade individual veins. The number 1 vein averaged 7 feet thick and contained 0.53 to 0.73 ounce of gold per ton; the number 2 vein averaged 3 feet thick and contained from 0.73 to 0.12 ounce of gold per ton; and the number 3 vein was about 5 feet thick with an average grade of 0.48 ounce of gold per ton (Redman and others, 1989).
Workings at the Jualin Mine include over 15,000 feet of workings on 5 levels. They included two inclined shafts, one 220 deep and the other 160 feet deep; a 310-foot main shaft; a 150-foot shaft; and the 5,000-foot Berners Tunnel (Redman and others, 1989). A 5.5-mile access road was completed from tidewater to the mine site in July, 1988 (Barnett, 1989). Core drilling as of the end of 1991 totaled 82,337 feet in 126 holes (Bundtzen and others, 1991). Coeur Alaska acquired the rights to the Jualin Mine area from International Curator Resources Ltd. in 1995 (Swainbank and others, 1995).
Geologic map unit (-135.046412428212, 58.8410724792975)
Mineral deposit model Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Hydrothermal muscovite from veins in the Jualin Mine gives ages of from 53.2 Ma to 55.5 Ma (Miller and others, 1994). This coincides with the 55 Ma age of the mesothermal gold-quartz-vein deposits elsewhere in the Juneau Gold Belt (Goldfarb and others, 1997).
Alteration of deposit Hydrothermal alteration adjacent to individual veins is characterized by reddish-brown ferroan dolomite (Miller and others, 1995). Other alteration includes sericitization of plagioclase, chloritization and sulfidization of mafic minerals, and albitization of feldspars (Leveille, 1991). The quartz-carbonate stockworks in the Jualin vein system feature three zones of alteration within and adjacent to the stockworks: 1) an inner zone of intense carbonate-sericite alteration; 2) an intermediate zone of mottled, dark-green diorite marked by cataclastic fabric and increased chlorite +/- sericite; and 3) an outer zone of equigranular diorite with abundant epidote, and locally, potassium feldspar (Barnett and others, 1989).

Production and reserves

Workings or exploration Workings at the Jualin Mine include over 15,000 feet of workings on 5 levels. These include two inclined shafts, one 220 deep and the other 160 feet deep; a 310-foot main shaft; a 150-foot shaft; and the 5, 000-foot Berners Tunnel (Redman and others, 1989). A 5.5-mile access road was completed from tidewater to the mine site in July, 1988 (Barnett, 1989). Core drilling as of the end of 1991 totaled 82,337 feet in 126 holes (Bundtzen and others, 1991).
Indication of production Yes
Production notes The Jualin deposit was discovered in 1895 and the mine began producing gold in 1896 when a 10-stamp mill was in operation. In 1914, the first semi-diesel generators in Alaska were installed. Between 1895 and 1929, the mine produced 37,913 ounces of gold from 74,624 tons of ore. The mill recovered 85-90 percent of the gold; 85 percent of the gold was free-milling and the remaining 15 percent was combined with sulfides (Redman and others, 1989).

References

MRDS Number A010694; A012016

References

Barnett, J.C., 1989, Jualin gold project, 1988 progress report, Berners Bay District: Unpublished report for International Curator Resources, Ltd., 75 p.
Barnett, J.C., Vandel, J.C., Monks, J.I., and Johnson, G.S., 1989, Jualin gold project, 1989 progress report: Unpublished report for Placer Dome U.S., Inc., 75 p.
Birak, D.J., 2006, Kensington gold project: Unpublished Technical Report for Cour d'Alene Mines, 116 p. (posted on www/.sedar.com, April 20, 2006).
Cheney, E.S., 1981, Geology of the Jualin gold property, Berners Bay district of the Juneau Gold Belt: Unpublished report for B-T Enterprises, Seattle, Wash.
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.
Kucinski, R., Porterfield, J., and Croff, C., 1985, Kensington Project summary report - 1985: Unpublished report for Placid Oil Co., 27 p.
Leveille, R.A., 1991, Geology and gold deposits of the Jualin mine area, Berners Bay district, southeastern Alaska: Fairbanks, University of Alaska, M.S. thesis, 200 p.
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
Miller, L.D., Goldfarb, R.J., Snee, L.W., Gent, C.A., and Kirkham, R.A., 1995, Structural geology, age, and mechanisms of gold vein formation at the Kensington and Jualin deposits, Berners Bay district, southeast Alaska: Economic Geology, v. 90, p. 343-368.
Woollett, G.N., 1990, Jualin Project: Unpublished report for International Curator International Resources, Ltd., Denver, Colo., 13 p.
Reporters J.C. Barnett and L.D. Miller (Juneau, Alaska ); D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008