|Quadrangle map, 1:250,000-scale||PE|
|Quadrangle map, 1:63,360-scale||C-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The North Silver North prospect is about 0.6 mile west of Mount Waters and about 0.4 mile east of the center of section 6, T. 62 S., R. 85 E. The workings are in an area about 400 feet wide and 1,000 feet in length; the location is at about the center of the main exposures of the mineralization. The location is accurate and a map of the workings is Figure 27 of Still and others (2002).|
The rocks in the prospect area are part of a belt of Mesozoic or Paleozoic sedimentary and volcanic rocks that have been metamorphosed to schist and gneiss. The belt is about 1 1/2 mile wide and strikes northwest (Brew, 1997; George and Wyckoff, 1973). The metamorphic rocks are bounded on the east by a thick, regionally extensive, 60 to 70 Ma tonalite sill and on the west by a 90 Ma granodiorite pluton (Brew, 1997 Still and others, 2002). The metamorphic rocks at the prospect include several prominent thin marble layers and a quartzite layer. On the north side of Groundhog Basin about two miles to the southwest, the metamorphic rocks are intruded by a 16.3 Ma biotite 'tin' granite pluton. The granite is probably the source of the numerous rhyolite dikes and sills that extend from it and the mineralization in the area (Newberry and Brew, 1989).
In the late 1950s, Moneta Porcupine Company staked claims in the area but subsequently dropped them William Huff and James Fucas continued work in the area and Huff discovered the North Silver North prospect in 1963. Their claims were optioned by the Bunker Hill Mining Company in 1965 and they drilled 7 holes, 85 to 224 feet deep, and blasted several pits. Bunker Hill dropped the claims at the end of the field season and the property was optioned by a succession of companies, Humble Oil and Refining Company, El Paso Natural Gas Company and AMAX Exploration Inc., through 1981. Still and others (2002) sampled the prospect during a Bureau of Land Management mineral assessment of the area.
The North Silver North prospect is associated with crosscutting, northeast trending, steeply dipping fault zones that are associated with irregular sulfide-bearing veins and lenses of quartz with sulfides. The quartz veins and lenses make up less than 10 percent of the faults (Still and others, 2002). To the east, the veins extend into limestone beds up to 30 feet thick that contain replacement deposits.The two most prominent veins are along the Bear and Camp faults which approach to within 80 feet of each other (Still and others, 2002). The Black Bear vein can be traced for about 1,000 feet and consists of scattered lenses of quartz with pyrite, sphalerite, and galena. The best mineralization exposed on the surface of the Black Bear vein was about 4 feet thick and a sample contained 39.1 parts per million (ppm) silver, 3.3 percent lead, and 2.39 percent zinc. A 1-foot sample collected nearby contained 92 ppm silver, 9.9 percent lead, and 4.1 percent zinc. Several drill holes on the vein cut mineralization with lesser values at depth. The Camp vein is about 0.2 to 4 feet thick and can be traced for about 350 feet. It consists of scattered quartz lenses with pyrite, sphalerite, and galena. The best mineralization exposed at the surface is about 0.4 feet thick and a sample across it contained 119.32 ppm silver. 48.61 percent lead, and 3.6 percent zinc. Two marble beds 4 to 50 feet thick can be traced for several thousand feet. Irregular bands and lenses of disseminated to massive pyrite, sphalerite, and galena are scattered along the marble for about 600 feet. The individual bands and lenses are 0.5 to 9 feet thick and extend from 3 to 100 feet. The best mineralization was a 6-foot-thick layer that contained 58 ppm silver, 5,114 ppm lead, and 12,758 ppm zinc.
|Geologic map unit||(-132.045280954007, 56.5235658984257)|
|Mineral deposit model||Scattered Ag-Pb-Zn quartz veins and lenses along fault zones and Ag-Pb-Zn replacement deposits in marble.|
|Age of mineralization||Probably related to a nearby 16.3 Ma biotite granite pluton.|
|Alteration of deposit||None specifically noted.|
|Workings or exploration||In the late 1950s, Moneta Porcupine Company staked claims in the area but subsequently dropped them. William Huff and James Fucas continued work in the area and Huff discovered the North Silver North prospect in 1963. Their claims were optioned by the Bunker Hill Mining Company in 1965 and they drilled 7 holes, 85 to 224 feet deep, and blasted several pits. Bunker Hill dropped the claims at the end of the field season and the property was optioned by a succession of companies through 1981: Humble Oil and Refining Company, El Paso Natural Gas Company, and AMAX Exploration Inc. Still and others (2002) sampled the prospect during a Bureau of Land Management mineral assessment of the area.|
|Indication of production||None|
Brew, D.A., 1997, Reconnaissance geologic map of the Petersburg C-1 Quadrangle, Southeastern Alaska: U.S. Geological Survey Open-File Report 97-156-H, 23 p., 1 sheet, scale 1:63,360
George, R.H., and Wyckoff, B.S., 1973, Whistlepig mineral exploration program, Alaska, Final report 1972 (with attached diamond drill hole logs and analyses): Unpublished El Pas National Gas Company report 109 p. 12 sheets (on file at the Bureau of Land Management, Minerals Information Center, Juneau Alaska).
Newberry, R.J., and Brew, D.A., 1989, Epigenetic hydrothermal origin of the Groundhog Basin-Glacier Basin silver-tin-lead-zinc deposits, southeastern Alaska: U.S. Geological Survey Bulletin 1903, p. 113-121.
Still, J.C., Bittenbender, P.E., Bean, K.W., and Gensler, E.G., 2002, Mineral assessment of the Stikine area, central southeast Alaska: Bureau of Land Management Technical Report 51, 560 p.
|Reporters||D.J. Grybeck (Port Ludlow, WA)|
|Last report date||3/4/2008|