Exchange

Prospect, Active?

Commodities and mineralogy

Main commodities Ag; Au; Pb
Ore minerals galena; gold; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale PE
Quadrangle map, 1:63,360-scale B-2
Latitude 56.4219
Longitude -132.5338
Nearby scientific data Find additional scientific data near this location
Location and accuracy This long-known prospect is in and just above the intertidal zone near Wedge Point on Woronkofski Island. It is about 0.6 mile west of the center of section 7, T. 63 S., R. 84 E. The location is accurate.

Geologic setting

Geologic description

The Exchange prospect was first staked in 1900 and has been described several times in similar terms (Wright and Wright, 1908; Roehm, 1945; Still and others, 2002). The workings include open cuts and two short adits. Two of the claims were restaked in 1974, were active through at least 1982, and were probably still active in 1996. Karl and others (1999) map the rocks in the area as part of the Jurassic or Cretaceous Seymour Canal Formation which is mainly graywacke. However, the prospect is in intrusive rocks that are probably similar to the Cretaceous tonalite that makes up much of Woronkofski Island (Still and others, 2002). The deposit consists of an irregular quartz vein that strikes north and dips 30W; it is up to 16 feet thick and can be traced for 250 feet. The vein contains small amounts of galena and pyrite. Still and others (2002) collected nine samples. The highest grade was a 5-foot sample across the vein; it contained 923 parts per billion gold, 26.6 parts per million (ppm) silver, and 944 ppm lead.
Geologic map unit (-132.535492730795, 56.4215535136899)
Mineral deposit model Gold-quartz vein.
Age of mineralization Probably Cretaceous or younger based on the probably age of the intrusive host rocks.

Production and reserves

Workings or exploration The property was first staked in 1900 and developed by surface trenches and two short adits. Two of the claims were restaked in 1974, were active through at least 1982, and were probably still active in 1996.
Indication of production None
Production notes No record of production.

References

MRDS Number A010327

References

Still, J.C., Bittenbender, P.E., Bean, K.W., and Gensler, E.G., 2002, Mineral assessment of the Stikine area, central Southeast Alaska: U.S. Bureau of Land Management Technical Report 51, 560 p.
U.S. Bureau of Mines, 1980, Claim map, Petersburg quadrangle, Alaska: U.S. Bureau of Mines Map 117, 1 sheet, scale 1:250,000.
Reporters D.J. Grybeck (Port Ludlow, WA)
Last report date 4/8/2007