Enterprise

Mine, Inactive

Alternative names

Arizona

Commodities and mineralogy

Main commodities Au
Other commodities Cu; Pb; Zn
Ore minerals chalcopyrite; galena; gold; pyrite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale TR
Quadrangle map, 1:63,360-scale A-6
Latitude 58.045
Longitude -133.9678
Nearby scientific data Find additional scientific data near this location
Location and accuracy This mine is indicated by a mine symbol on the Taku River A-6 topographic map. It is on the north side of Limestone Inlet at an elevation of 1,600 feet, in the NE1/4NE1/4 section 21, T. 44 S., R. 70 E. of the Copper River Meridian.

Geologic setting

Geologic description

The deposit at the Enterprise Mine consists of two parallel, sheeted quartz veins, 3 inches to 9 feet thick and several hundred feet long, that strike N 25 E and dip 45 NW. The veins contain free gold and small amounts of galena, sphalerite, pyrite, and chalcopyrite. Wells and others (1986) describe the host rocks as slate and greenstone intruded by Cretaceous porphyritic diorite. Redman and others (1989) describe the Enterprise vein as cutting porphyritic biotite-hornblende granite. According to Roehm (1936), at least one of the veins is well-defined and shows evidence of some normal-fault movement parallel to the vein. Roehm reports that gold values decrease with depth. Samples from the lower adit assayed 0.01 to 0.22 ounce of gold per ton, and samples from a raise in the adit assayed 0.06 to 0.48 ounce of gold per ton. Samples from the upper adit assayed 0.12 to 0.98 ounce of gold per ton and samples from an open cut above the adit assayed 1.34 ounces of gold per ton (Roehm, 1936). U.S. Bureau of Mines samples collected in 1988 contain similar amounts of gold (Redman and others, 1989). Redman and others (1989) describe carbonate alteration that is restricted to within an inch or two of the margins of the veins.
The deposit was probably discovered about 1905 (Redman and others, 1985), and there was some surface activity prior to 1911 (Knopf, 1911). Currently (2001), there are 800 feet of surface trenches and at least two adits, including a 120-foot-long upper adit and a 320-foot-long lower adit. In 1934, a 52-foot inclined raise was driven by H. Jackson and A. Westhall. A stamp mill on the property had five, 1250-pound stamps (Roehm, 1936). By 1914, 200 tons of ore had been processed in a Johnson rod mill; at least 15 ounces of gold and a small amount of silver were recovered. Later in 1914, B.L. Thane took over the property and recovered 85 ounces of gold from 300 tons of ore that was processed in a five-stamp mill (Roehm, 1936). The Enterprise mine has an inferred resource of 24,600 short tons of ore with an average of 0.23 ounce of gold per ton (Redman and others, 1989).
Geologic map unit (-133.969544052917, 58.0446682596947)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization The veins apparently formed between 56 Ma and 53 Ma (Miller and others, 1994).
Alteration of deposit Carbonate alteration is restricted to within an inch or two of the margins of the veins (Redman and others, 1989).

Production and reserves

Workings or exploration The deposit was probably discovered about 1905 and there was some surface activity prior to 1911 (Knopf, 1911; Redman and others, 1985). Currently (2001), there are 800 feet of surface trenches and at least two adits, including a 120-foot-long upper adit and a 320-foot-long lower adit. In 1934, a 52-foot inclined raise was driven by H. Jackson and A. Westhall. A stamp mill on the property had five, 1,250-pound stamps (Roehm, 1936).
Indication of production Yes; small
Reserve estimates The Enterprise mine has an inferred resource of 24,600 short tons of ore with an average grade of 0.23 ounce of gold per ton (Redman and others, 1989).
Production notes By 1914, 200 tons of ore had been processed in a Johnson rod mill; at least 15 ounces of gold and a small amount of silver were recovered. Later in 1914, B.L. Thane took over the property and recovered 85 ounces of gold from 300 tons of ore that was processed in a 5-stamp mill (Roehm, 1936).

References

MRDS Number A012527

References

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 11/27/2001