Midas

Mine, Probably inactive

Alternative names

Granby Consolidated Mining, Smelting, And Power Co.

Commodities and mineralogy

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

Geographic location

Quadrangle map, 1:250,000-scale VA
Quadrangle map, 1:63,360-scale A-7
Latitude 61.0132
Longitude -146.2798
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Midas mine is on the west side of Solomon Gulch, about 1.3 miles south of Solomon Lake. The location of this mine by name is shown on the USGS Valdez A-7 topographic map (1996). This is also the location of the Jumbo Lode claim. The All American Lode claim is shown on this map as a shaft, one-half mile southeast of the Midas mine adit. This is locality 40 of Cobb and Matson (1972) and locality 32 of Winkler and others (1981 [OFR 80-892-B]).

Geologic setting

Geologic description

Crudely stratiform massive vein and disseminated replacement deposits containing pyrite, pyrrhotite, chalcopyrite, and sphalerite occur in slate and metagraywacke of the Upper Cretaceous Valdez Group (Johnson, 1915; 1919; Rose, 1965). The mineralized zones are rich in quartz and pyrite. They are locally remobilized along fractures to form crosscutting, polymetallic sulfide-bearing, quartz-calcite veins and fracture fillings. The deposits are generally restricted to shear zones that strike N76W to S62W and dip 40 to 70 degrees north. The Jumbo lode ranged from a few inches to 20 feet in thickness and averaged 3 to 4 feet of ore width in a shear zone about 1000 feet long. The All-American lode is wider but of lower grade. Production from this mine was from the Jumbo lode and totaled more than 3,000,000 pounds of copper (Rose, 1965). In 1917, 21,000 tons of ore averaged 4.15 percent copper, 0.42 ounce of silver per ton, and 0.062 ounce of gold per ton. In 1918, 25,350 tons of shipped ore averaged 3.24 percent copper, 0.25 ounce of silver per ton, and 0.05 ounce of gold per ton. U.S. Bureau of Mines chip samples contained 0.11 to 6.3 percent copper, 0.26 to 3.1 percent zinc, less than 0.005 to 0.66 ounce of gold per ton, and less than 0.2 to 0.6 ounce of silver per ton (Jansons and others, 1984).
The All American lode was discovered in 1901 and the Jumbo lode in 1906. Most production occurred from 1911 to 1919. The Jumbo lode was developed on four levels through at least 650 feet of vertical extent; the underground workings aggregated about 4,000 feet in length. Only the 600-foot-long third-level adit was not caved in 1964 (Rose, 1965). The All-American lode was explored with a shallow shaft and open cuts. More recent exploration has occurred and may have included drilling (Cobb, 1979 [OFR 79-1241]).
The country rocks are mostly slate and metagraywacke but some mafic greenstone bodies are locally present and some felsic dikes cut the metamorphic rocks (Johnson, 1915). The mafic rocks have been described as intrusive into the metasedimentary rocks. The rocks include siliceous schist (Grant, 1906) and quartzite (Johnson, 1919); sedimentary features are well developed in ore from this deposit (Crowe and others, 1992). The deposits are considered to be submarine volcanogenic in origin (Winkler and others, 1981 [OFR 80-892-B]; Crowe and others, 1992).
Geologic map unit (-146.281796570018, 61.0126721558711)
Mineral deposit model Besshi massive sulfide deposit (Cox and Singer, 1986; model 24b)
Mineral deposit model number 24b
Age of mineralization Late Cretaceous, the age of the enclosing sedimentary rocks of the Valdez Group.
Alteration of deposit Silicification, the mineralized zones are rich in quartz and pyrite.

Production and reserves

Workings or exploration The All American lode was discovered in 1901 and the Jumbo lode in 1906. Most production occurred from 1911 to 1919. The Jumbo lode was developed on four levels through at least 650 feet of vertical extent; the underground workings aggregated about 4,000 feet in length. Only the 600-foot-long third-level adit was not caved in 1964 (Rose, 1965). The All-American lode was explored with a shallow shaft and open cuts. More recent exploration has occurred and may have included drilling (Cobb, 1979 [OFR 79-1241]).
Indication of production Yes; small
Reserve estimates Rose (1965) estimated that the reserves at the Midas mine are about 60,000 tons of material that contains 1.6 percent copper.
Production notes Between 1911 and 1919, the Jumbo lode produced 3,385,000 pounds of copper, 2,569 ounces of gold, and 15,157 ounces of silver (Rose, 1965). This production was from 49,350 tons of ore. In 1917, 1,000 tons of ore averaged 4.15 percent copper, 0.42 ounce of silver per ton, and 0.062 ounce of gold per ton. In 1918, 25,350 tons of ore averaged 3.24 percent copper, 0.25 ounce of silver per ton, and 0.05 ounce of gold per ton.

References

MRDS Number A011481

References

Reporters Travis L. Hudson
Last report date 12/14/2001