Sixmile

Prospect, Undetermined

Commodities and mineralogy

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

Geographic location

Quadrangle map, 1:250,000-scale KC
Quadrangle map, 1:63,360-scale D-1
Latitude 55.995
Longitude -130.066
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is at about 200 feet elevation, adjacent to the east side of the Salmon River road about 6 miles north-northwest of the town of Hyder. The site is at the northwest corner of section 11, T. 68 S., R. 99 E., of the Copper River Meridian. It corresponds to loc. 12 on plate 2 in Buddington (1929 [B 807]), and to loc. 4 in Elliott and others (1978). The location is accurate within 0.1 mile.

Geologic setting

Geologic description

The country rocks in the area of this site include: pelitic metasedimentary and subordinate andesitic metavolcanic strata of the Jurassic or Triassic Hazelton Group; recrystallized granodiorite of the Triassic Texas Creek Granodiorite, which intrudes the Hazelton rocks; quartz monzonite and granodiorite of the Hyder Quartz Monzonite batholith, which intrudes the Hazelton and Texas Creek rocks; and Tertiary lamprophyre dikes, which intrude all of the foregoing rock units (Buddington, 1929; Smith, 1973, l977; Berg and others, 1988).
The deposit consists of sulfide-bearing quartz fissure veinlets in a shear zone 5 inches to 5 feet wide in (Texas Creek) granodiorite (Buddington, 1929, p. 76-77; Elliott and others, 1978, loc. 4; Cobb and Elliott, 1980, p. 97; Maas and others, 1995, p. 261). Some of the stringers are rich in free gold, which occurs in the borders of the stringers and in the adjacent granodiorite. Some of the stringers also carry galena, sphalerite, chalcopyrite, and pyrite; and some of these sulfides also are disseminated, or face fractures, in the granodiorite adjacent to the veins.
Maas and others (1995, p. 254) suggest that sulfide-bearing quartz fissure veins hosted by Texas Creek Granodiorite at the Six Mile prospect are Eocene in age. If so, the age of the deposit is roughly contemporaneous with emplacement of the Hyder Quartz Monzonite batholith.
The prospect was explored in the early 1900s by two adits, 25 and 35 feet long. Picked samples of the richest veins assayed as much as 1080 oz. Au/ton and 200 oz. Ag/ton; samples of the wallrock granodiorite contained an average of 0.05 oz. Au/ton and 2.5 oz. Ag/ton. Samples of a 35-foot-long vein sampled by the U.S. Bureau of Mines in the early 1990s contained up to 3.77 ppm Au, 195.8 ppm Ag, and 2.89% Pb (Maas and others, 1995, p. 261).
Geologic map unit (-130.06770423558, 55.9947037910189)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986; model 22c)
Mineral deposit model number 22c
Age of mineralization Maas and others (1995, p. 254) suggest that sulfide-bearing quartz fissure veins hosted by Texas Creek Granodiorite at the Six Mile prospect are Eocene in age. If so, the age of the deposit is roughly contemporaneous with emplacement of the Hyder Quartz Monzonite batholith.

Production and reserves

Workings or exploration The prospect was explored in the early 1900s by two adits, 25 and 35 feet long. Picked samples of the richest veins assayed as much as 1080 oz. Au/ton and 200 oz. Ag/ton; samples of the wallrock granodiorite contained an average of 0.05 oz. Au/ton and 2.5 oz. Ag/ton. Samples of a 35-foot-long vein sampled by the U.S. Bureau of Mines in the early 1990s contained up to 3.77 ppm Au, 195.8 ppm Ag, and 2.89% Pb (Maas and others, 1995, p. 261).
Indication of production Undetermined

References