Bessie

Mine, Active

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Pb; Zn
Ore minerals arsenopyrite; galena; native gold; pyrite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale JU
Quadrangle map, 1:63,360-scale C-3
Latitude 58.5895
Longitude -134.8677
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Bessie Mine is at an elevation of about 2,200 feet, between Bessie Creek and South Fork Cowee Creek. The mine site is marked on the Juneau C-3 topographic map, in the SE1/4 section 8, T. 38 S., R. 64 E. of the Copper River Meridian. The location is accurate.

Geologic setting

Geologic description

The deposit at the Bessie Mine consists of a quartz vein in metamorphosed volcanic conglomerate that contains well-rounded pebbles up to 5 inches diameter. The conglomerate has a sheared contact with graywacke and black phyllite. The vein strikes N 77 E and dips steeply to the southeast. The vein displays ribbon structures and varies from 8 inches to 3 feet thick, averaging 1 foot thick. It contains pyrite, with minor sphalerite, arsenopyrite, galena and native gold (Redman and others, 1989; Roehm, 1936). Thirteen panel samples taken by Monument Resources in 1988 along 70 feet of exposed quartz vein in one of the drifts had a weighted average of 0.347 ounce of gold per ton (Barnett, 1988). The Bessie deposit was discovered in 1897 and developed by two adits and a shaft. One adit was driven 175 feet to the vein and then drifts along it for 75 feet. Another adit follows the vein along strike for 245 feet. The mine is estimated to have produced 150 ounces of gold prior to 1913, which is half of the combined production of the Bessie and Aurora Borealis mines (JU084) (Redman and others, 1989). The U.S. Bureau of Mines estimates that the Bessie Mine contains a resource of 19,000 tons of ore that contains 0.2 ounce of gold per ton with an average width of 3 feet. The mine area was explored by Noranda in 1981 and by Monument Resources in 1988. Monument Resources drilled 5 holes on the Bessie (JU085) and the Aurora Borealis properties in 1988. The holes intersected 2 narrow veins, each assaying more than 1.1 ounces of gold per ton (Barnett, 1988).
This prospect is in the Juneau Gold Belt, which consists of more than 200 gold-quartz-vein deposits that have produced nearly 7 million ounces of gold. These gold-bearing mesothermal quartz vein systems form a zone 160 km long by 5 to 8 km wide along the western margin of the Coast Mountains. The vein systems are in or near shear zones adjacent to west-verging, mid-Cretaceous thrust faults. The veins are hosted by diverse, variably metamorphosed, sedimentary, volcanic, and intrusive rocks. From the Coast Mountains batholith westward, the host rocks include mixed metasedimentary and metavolcanic sequences of Carboniferous and older, Permian and Triassic, and Jurassic-Cretaceous age. The sequences are juxtaposed along mid-Cretaceous thrust faults (Miller and others, 1994). The sequences are intruded by mid-Cretaceous to middle Eocene plutons, mainly diorite, tonalite, granodiorite, quartz monzonite, and granite. Sheetlike tonalite plutons emplaced just east of the Juneau Gold Belt and undeformed granite and granodiorite bodies that are emplaced farther to the east are between 55 and 48 Ma (Gehrels and others, 1991). The structural grain of the belt is defined by northwest-striking, moderately to steeply northeast-dipping, penetrative foliation that developed between Cretaceous and Eocene time (Miller and others, 1994). The majority of the veins in the Juneau Gold Belt strike northwest. 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 (-134.869492307694, 58.5891753933214)
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).

Production and reserves

Workings or exploration The Bessie mine was discovered in 1897 and developed by two adits and a shaft. The mine area was explored by Noranda in 1981 and by Monument Resources in 1988. Monument Resources drilled 5 holes on the Bessie (JU085) and the Aurora Borealis properties in 1988. The holes intersected 2 narrow veins, each assaying more than 1.1 ounces of gold per ton (Barnett, 1988).
Indication of production Yes; small
Reserve estimates The U.S. Bureau of Mines estimates that the Bessie Mine contains a resource of 19,000 tons of ore that contains 0.2 ounce of gold per ton, with an average vein width of 3 feet (Redman and others, 1989).
Production notes The mine is estimated to have produced 150 ounces of gold prior to 1913, which is half of the combined production of the Bessie and Aurora Borealis mines (JU084) (Redman and others, 1989).

References

MRDS Number A012030

References

Barnett, J.C., 1988, 1988 Summary report, Bessie gold project: Unpublished report for Monument Resources, Ltd., 35 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.
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