Silver King

Prospect, Probably inactive

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb; Zn
Other commodities As; Sb
Ore minerals argentiferous galena; chalcopyrite; pyrite
Gangue minerals ankerite; quartz; siderite

Geographic location

Quadrangle map, 1:250,000-scale WI
Quadrangle map, 1:63,360-scale B-3
Latitude 67.2891
Longitude -151.3251
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Silver King prospect is along the north side of Michigan Creek about 2 miles east of Wild River at an elevation of about 1,100 feet. It is about 0.3 mile west of the top of hill 1370, near the northwest corner of section 34, T. 29 N., R. 17 W. Kurtak and others (2002: fig. I-5 and I-6) provide several excellent maps of the prospect. See figures I-5 and I-6 of Kurtak and others (2002) for a map of the prospect. The location is accurate.

Geologic setting

Geologic description

Dillon and others (1986) describe the rocks in the area as Middle Devonian calcareous and chlorite-quartz schist interbedded with quartz-mica schist and marble. This schist unit is overlain by metabasites and felsic volcanic rocks of the Devonian and Mississippian Ambler metavolcanic sequence. The schist is locally deformed into broad, open folds.
Early descriptions of the Silver King prospect, beginning with Schrader (1904) describe it as argentiferous galena-bearing quartz veins in phyllite. Reed (1938) described several poorly exposed outcrops and float of galena-bearing quartz veins about 5 to 6 feet thick. A small adit noted by Reed that apparently did not cut mineralization is now caved. A 20-foot-long trench is about 100 feet north of the adit.
Nokleberg and others (1987 and 1996) characterize the occurrence as a Kuroko massive sulfide deposit. They describe the mineralization as 3- to 4-inch-thick zones of disseminated to massive chalcopyrite and argentiferous galena in felsic schist, with crosscutting pyrite veins. The country rocks are felsic schist, marble and phyllite of the Ambler sequence. Grab samples of the mineralized material contained up to 8.2 percent arsenic, 8.3 grams of gold per tonne, 3.9 grams of silver per tonne, 0.14 percent copper, 0.03 percent zinc, and 0.014 percent lead.
Kurtak and others (2002) mapped and sampled the mineralization . They interpret the deposit as quartz and quartz-carbonate veins 0.5 to 7.0 feet thick that trend northwest to northeast and can be traced for up to 80 feet along strike. The veins contain isolated clots and stringers of galena with minor pyrrhotite and chalcopyrite. A picked sample of galena-bearing quartz contained 121.9 parts per million (ppm) silver and 5.78 percent lead. Another sample from a 7-foot-thick quartz vein contained 64.5 ppm silver, 5.34 percent lead, and 2,000 ppm antimony. Locally, large pieces galena with minor pyrrhotite and chalcopyrite can be found in float; one assayed 583 ppm silver and 168 parts per billion gold.
About a thousand feet upstream from the main prospect in the gorge of Michigan Creek, at least 5 quartz veins 0.5 to 10-feet thick are exposed in the canyon walls. The veins strike about N10W and cut across the schistosity of the wall rocks. A chip sample across a 0.5-foot-wide vein contained 650 ppm silver.
Geologic map unit (-151.327828902724, 67.2886462473025)
Mineral deposit model Galena-quartz veins or Kuroko massive sulfide? (Cox and Singer, 1986; model 28a?).
Mineral deposit model number 28a?
Age of mineralization Interpreted as different workers as either epigenetic galena-quartz veins that cut Devonian schist or as a Kuroko massive-sulfide deposit related to the felsic rocks of the Devonian and Mississippian Ambler sequence.
Alteration of deposit Not specifically noted.

Production and reserves

Workings or exploration Before 1938, a 7x7 foot adit, 75 feet long, was driven into the north wall of the canyon of Michigan Creek, probably to undercut a vein exposed in a surface trench about 150 feet north and 100 feet higher than the portal of the adit. This adit was caved in 1999 (Kurtak and others, 2002). Mapped and sampled by several government agencies.
Indication of production None
Reserve estimates None.
Production notes None.

References

MRDS Number A011952

References

Kurtak, J.M., Klieforth, R.F., Clark, J.M., and Maclean, E.A., 2002, Mineral investigations in the Koyukuk mining district, northern Alaska: Final Report: U.S. Bureau of Land Management Technical Report 50, v. 1 and 2, 845 p.
Reporters J.M. Britton (Anchorage); D.J. Grybeck (Contractor, USGS)
Last report date 2/1/2011