Friday

Mine, Undetermined

Commodities and mineralogy

Main commodities Au
Other commodities Cu
Ore minerals chalcopyrite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SD
Quadrangle map, 1:63,360-scale D-6
Latitude 57.97837
Longitude -133.79041
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Friday Mine is shown by name on the USGS 1:63,360-scale topographic map. It is about 0.3 mile southwest of the center of section 18, T. 45 S., R. 72 E. The underground workings of the Friday Mine are shown on Figure D-218 of Redman and others (1989).

Geologic setting

Geologic description

The Friday Mine was discovered in the 1880s and work started in 1898. By 1899, there were 400 feet of workings (Spencer, 1906; Redman and others, 1989). A 10-stamp mill was erected in 1900 and 10 more stamps were added in 1901 to process the ore from the Friday Mine and from the nearby Minnehaha and Finale adits (SD002) which were being operated by the same company. By 1903, the company had produced a few hundred tons of ore from the Friday and Minnehaha adits. However, mining was not profitable and the mine closed in 1905 after an attempt to reopen it. The Friday Mine has three adits: a 20-foot adit at an elevation of about 500 feet, an upper adit at an elevation of about 425 feet, and a lower adit with about 725 feet of workings. There is also a stope that extends from the upper adit at an elevation of about 425 feet to the surface at an elevation of about 500 feet. The Friday Mine produced about 350 tons of ore that contained 75-150 ounces of gold.
The deposit at the Friday Mine consists of a quartz vein in the Snettisham biotite-magnetite pyroxenite of Cretaceous age (Gehrels and Berg, 1992). The vein is associated with two stages of tabular, trondhjemite dikes that at the Friday Mine are generally steeply dipping (Redman and others, 1989). The early trondhjemite dikes are barren of mineralization. The later dikes vary laterally from trondhjemite to massive mineralized quartz with borders of trondhjemite aplite. The veins, dike, and host rocks are cut by 3 or 4 flat-lying faults which to the southeast coalesce into a single large thrust fault at the Crystal Mine (SD005). The quartz vein in the Friday adits is up to 4 feet thick and extends laterally for several hundred feet. It contains up to 25 percent pyrite and minor chalcopyrite. The trondhjemite dikes in the workings contain about 0.5 to 5 percent pyrite. The vein is bordered by up to 2 feet of serpentinized pyroxenite.
Redman and others (1989) collected 12 samples from the stope of the upper adit. The samples contained a weighted average of 7.4 parts per million gold across an average vein thickness of 1.6 feet. Six samples from the lower Friday adit contained a weighted average of 1.0 ppm gold across an average vein thickness of 1.0 feet. From these data, they estimated an indicated resource of 600 short tons of material with a grade of 0.22 ounce of gold per ton.
Geologic map unit (-133.792148006712, 57.9780348969245)
Mineral deposit model Gold-pyrite vein in pyroxenite.
Age of mineralization Cretaceous or younger based on the age of the host rock.
Alteration of deposit The mineralized quartz vein is bordered by up to 2 feet of serpentinized pyroxenite.

Production and reserves

Workings or exploration The Friday Mine was discovered in the 1880s and work started in 1898. By 1899, there were 400 feet of workings (Spencer, 1906; Redman and others, 1989). A 10-stamp mill was erected in 1900 and 10 more stamps were added in 1901 to process the ore from the Friday Mine and from the nearby Minnehaha and Finale adits (SD002) which were being operated by the same company. By 1903, the company had produced a few hundred tons of ore from the Friday and Minnehaha adits. However, mining was not profitable and the mine closed in 1905 after an attempt to reopen it. The Friday Mine has three adits: a 20-foot adit at an elevation of about 500 feet, an upper adit at an elevation of about 425 feet, and a lower adit with about 725 feet of workings. There is also a stope that extends from the upper adit at an elevation of about 425 feet to the surface at an elevation of about 500 feet.
Indication of production Yes; small
Reserve estimates Redman and others (1989) estimated an indicated resource of 600 short tons of material with a grade of 0.22 ounce of gold per ton.
Production notes The Friday Mine produced about 350 tons of ore that contained 75-150 ounces of gold.

References