Patton

Mine, Inactive

Alternative names

Montana Basin

Commodities and mineralogy

Main commodities Au
Other commodities Ag
Ore minerals arsenopyrite; gold
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale JU
Quadrangle map, 1:63,360-scale B-2
Latitude 58.4696
Longitude -134.6533
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Patton Mine is at an elevation of approximately 2,700 feet, on a southwest-facing slope, 1 mile northeast of the divide between Windfall Creek and Montana Creek. It is in the SE1/4SE1/4 section 22, T. 39 S., R. 65 E. of the Copper River Meridian. The location is accurate within 1/4 mile.

Geologic setting

Geologic description

The Patton Mine was discovered in 1882. The workings include 5 adits with 500 feet of underground workings, and numerous trenches. There is some production of gold reported, but the amount is not documented. Based on the volume of the stopes, the U.S. Bureau of Mines estimates that at least 35 tons of ore was mined. Ore was roasted and treated in an arrastre (Redman and others, 1989). The deposit consists of two types of veins, both in biotite schist: 1) conformable, quartz stringer veins that strike northwest and dip 70-80 northeast that contain pyrite, but little gold; and 2) quartz veins that strike east-west and dip 55-65 north, are up to 2 feet thick and slightly crosscut foliation, and contain arsenopyrite and native gold (Knopf, 1912). The auriferous veins are associated with fault gouge and have slickensides along the vein margins. U.S. Bureau of Mines samples of quartz vein contained up to 76.3 ppm gold (Redman and others, 1989).
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 (-134.655086505382, 58.4692739380684)
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 deposit at the Patton Mine was discovered in 1882. The workings include 5 adits with 500 feet of underground workings, and numerous trenches.
Indication of production Undetermined
Production notes There is some production of gold reported but the amount is not documented. Based on the volume of the stopes, the U.S. Bureau of Mines estimates that at least 35 tons of ore was mined.

References

MRDS Number A012019

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., 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