South Silver Prospect, Petersburg Mining District, Wrangell City and Bourough, Alaska, USAi

Regional Level Types
South Silver Prospect	Prospect
Petersburg Mining District	Mining District
Wrangell City and Bourough	Borough
Alaska	State
USA	Country

Location: El Paso Natural Gas Company collected samples along a line about 1,900 feet long trending south-southwest, beginning near Peak 4326 at the head of Groundhog Basin. They then drilled a 149-foot hole about 0.1 mile southwest of Peak 4326; the coordinates for the prospect are at the drill hole. The prospect is about 0.6 mile east-southeast of the center of section 7, T. 62 S., R. 86 E. The location is accurate.
Geology: The rocks in the prospect area are part of a belt of Mesozoic or Paleozoic sedimentary and volcanic rocks that have been metamorphosed to Tertiary or Cretaceous 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). On the north side of Groundhog Basin, the metamorphic rocks are intruded by a 16.3 Ma biotite 'tin' granite pluton about 1,000 by 2,0000 feet in size. 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). El Paso Natural Gas Company worked in the area from 1971 to 1976 (George and Wyckoff, 1973). They collected more than 200 surface samples along a line about 1,900 feet long that extended south-southwest from Peak 4326. They also drilled a hole 149 feet deep about 0.1 mile southwest of Peak 4326. Still and others (2002) identified the mineralization as quartz veins and stringers up to 10 feet thick that follows the layering in the gneiss hostrock. Four samples contained up to 63.9 parts per million (ppm) silver, 1,417 ppm lead, and 1,089 ppm tin. In the samples El Paso Natural Gas Company collected, the 6 best surface samples contained 840 to 1,655 ppm zinc, and 320 to 2,720 ppm lead. A 32-foot intercept in the El Paso drill hole consisted of rhyolite and gneiss cut by quartz stringers with sphalerite and galena; the intercept averaged 0.7 percent zinc, 1.0 percent lead, and 0.3 ounce of silver per ton. The mineralization is almost certainly of the same origin and age as that at the nearby Groundhog Basin prospect (PE040).
Workings: El Paso Natural Gas Company worked in the area from 1971 to 1976. They collected more than 200 surface samples along a line about 1,900 feet long that extended south-southwest from Peak 4326. They also drilled a hole 149 feet deep about 0.1 mile southwest of Peak 4326.
Age: 16.3 Ma based on a genetic tie to a nearby, zinnwaldite 'tin' granite (Newberry and Brew, 1989).
Alteration: None specifically noted.
Reserves: None.

Commodities (Major) - Ag, Pb, Sn, Zn
Development Status: None
Deposit Model: Banded Ag-Cu-Sn-Pb-Zn tabular replacement bodies, veins, and stringers.

Other Databases

Link to USGS - Alaska:	PE106

Other Regions, Features and Areas containing this locality

References