Smith And Heid; Ashby-Torro Mine, Juneau Mining District, Juneau, Alaska, USAi

Regional Level Types
Smith And Heid; Ashby-Torro Mine	Mine
Juneau Mining District	Mining District
Juneau	City Borough
Alaska	State
USA	Country

Location: This mine is at an elevation of approximately 2,300 feet, on a northwest facing slope, 1 mile northeast of the divide between Windfall Creek and Montana Creek. It is near the center of the W1/2 section 22, T. 39 S., R. 65 E. of the Copper River Meridian. The location is accurate within 1/4 mile.
Geology: The Smith and Heid Mine was discovered in 1893. Workings include a 135-foot adit, a 170-foot adit, a 36-foot adit, and numerous trenches. It produced at least 205 ounces of gold between 1893 and 1937 (Redman and others, 1989). Ore was roasted and treated in an arrastre. The deposit consists of quartz veins and quartz stringer zones in an interbedded squence of black phyllite and chlorite schist . The veins trend northwest and dip 40-60 NE. The stringer zones are up to 35 feet thick and contain arsenopyrite, chalcopyrite, galena, gold, pyrite, pyrrhotite, and sphalerite. Oxidized exposures yield gold when panned (Knopf, 1912). Rusty, vuggy, felsic phyllite contain quartz stringers, and disseminated pyrrhotite is exposed underground. U.S. Bureau of Mines samples of these quartz stringers contain up to 107.8 ppm gold. Samples of the felsic phyllite did not contain significant 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).
Workings: The Smith and Heid Mine was discovered in 1893. Workings include a 135-foot adit, a 170-foot adit, a 36-foot adit, and numerous trenches.
Age: 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: At least 205 ounces of gold was produced between 1893 and 1937. Ore was roasted and treated in an arrastre.

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

Other Databases

Link to USGS - Alaska:	JU103

Other Regions, Features and Areas containing this locality

References