Minehaha

Mine, Undetermined

Alternative names

Finale

Commodities and mineralogy

Main commodities Ag; Au
Other commodities Cu; Pb
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 57.98351
Longitude -133.78532
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Minehaha and Finale adits are just south of the abandoned town of Snettisham, at or near the adit symbols shown on the USGS 1:63,360-scale topographic map. The adits are about 0.2 mile north of the center of section 8, T. 45 S., R. 72 E. The underground workings at the two adits are shown on Figures D-217 and D-218 of Redman and others (1989).

Geologic setting

Geologic description

Gold was discovered here in the 1880s and work started at this mine in 1898. By 1899, there were 400 feet of workings in this vicinity either in these adits or at the nearby Friday Mine (SD004) (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 the nearby Minnehaha and Finale adits which were being operated by the same company. By 1903, the company had produced a few hundred tons of ore from these adits and the Friday Mine. However, mining was not profitable and the property closed in 1905 after an attempt to reopen it. Redman and others (1989) were able to map 430 feet of the underground workings at the Finale the adit but the Minnehaha adit was caved and inaccessible. The Minnehaha adit produced some gold but the quantity is uncertain.
The deposit is similar to the nearby Friday Mine (SD004) and 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 Finale adit vary from flat laying to steep (Redman and others, 1989). The early trondhjemite dikes are barren of mineralization. The later dikes vary laterally from trondhjemite to massive quartz with borders of trondhjemite aplite. There are several sets of faults in the Finale adit. Most strike E-W and dip 45-65N; a subordinate set trends about S30E and dips NE. The vein contains up to 25 percent pyrite and is bordered by up to 2 feet of serpentinized pyroxenite.
Redman and others (1989) collected seven samples from the Finale adit. They averaged 3.1 parts per million (ppm) silver, 541 ppm copper, and 1,637 ppm lead. The gold content varied from 0.1 to 1.5 ppm gold. A dump sample from the Minnehaha adit contained 7.6 ppm silver and 0.4 ppm gold.
Geologic map unit (-133.787057923641, 57.9831750246683)
Mineral deposit model Gold-pyrite vein in pyroxenite.
Age of mineralization Cretaceous or younger based on the age of the host rocks.
Alteration of deposit The mineralized quartz vein is bordered by up to 2 feet of serpentinized pyroxenite.

Production and reserves

Workings or exploration Gold was discovered here in the 1880s and work started in 1898. By 1899, there were 400 feet of workings in this vicinity either in these adits or at the nearby Friday Mine (SD004) (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 the nearby Minnehaha and Finale adits which were being operated by the same company. By 1903, the company had produced a few hundred tons of ore from these adits and the Friday Mine. However, mining was not profitable and the property closed in 1905 after an attempt to reopen it. Redman and others (1989) were able to map 430 feet of the underground workings at the Finale adit but the Minnehaha adit was caved and inaccessible.
Indication of production Yes; small
Production notes The Minnehaha adit produced some gold from 1898 to 1903 but the quantity is unknown and is probably small.

References