Enterprise; Arizona Mine, Juneau Mining District, Juneau, Alaska, USAi

Regional Level Types
Enterprise; Arizona Mine	Mine
Juneau Mining District	Mining District
Juneau	City Borough
Alaska	State
USA	Country

Location: 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.
Geology: 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 5-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).
Workings: 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).
Age: The veins apparently formed between 56 Ma and 53 Ma (Miller and others, 1994).
Alteration: Carbonate alteration is restricted to within an inch or two of the margins of the veins (Redman and others, 1989).
Production: 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).
Reserves: 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).

Commodities (Major) - Au; (Minor) - Cu, Pb, Zn
Development Status: Yes; small
Deposit Model: Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)

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Link to USGS - Alaska:	TR021

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References