Lower Ledge; Haley and Rogers Prospect, Chichagof Mining District (Chicagof Mining District), Sitka, Alaska, USAi

Regional Level Types
Lower Ledge; Haley and Rogers Prospect	Prospect
Chichagof Mining District (Chicagof Mining District)	Mining District
Sitka	City Borough
Alaska	State
USA	Country

MAS number: 0021160016.
Location: The location of the Lower Ledge prospect is somewhat uncertain but it is probably at an elevation of about 430 feet along the creek that drains from Pinta Lake to the head of Silver Bay. The prospect is about 0.6 mile north-northeast of the center of section 32, T. 56 S., R. 65 E. The surface and underground workings are shown by Bittenbender and others (1999, figs. 22-24).
Geology: This deposit is one of many of similar deposits (PA002 to PA018) scattered over an area of about 6 square miles at the head of Silver Bay (Bittenbender and others, 1999). The deposits are gold-quartz veins with sparse sulfides, usually only pyrite and arsenopyrite. Samples that have been analyzed with modern methods usually show anomalous arsenic even if arsenopyrite is not identified in the rocks, and several parts per million mercury. The veins are often parallel to the bedding of the host rock which is graywacke and argillite of the Sitka Graywacke of Cretaceous age (Loney and others, 1975). Many of the so-called veins in the early literature are actually fault zones with lenses of quartz or concentrations of quartz stringers along the fault zone. Prospecting began in the area in 1871. The Stewart Mine (PA012) was located in 1872 and it was the first lode-gold mine in Alaska. The Silver Bay area has been prospected intermittently to the present but the veins are relatively small and most are low grade. The area has produced relatively little gold, many of the properties have not been active since before 1900, and there has been no production since the early 1940's. The early history and exact location of this prospect are obscure although it was mentioned in several early reports (Becker, 1898; Knopf, 1912). Bittenbender and others (1999, figs. 22-24) located a 63-foot adit and a flooded shaft that are probably the Lower Ledge prospect. The adit is along a 1.5-foot-thick fault zone that cuts graywacke and contains quartz stringers up to 1/2 inch thick. The shear zone strikes S70W and dips steeply south to vertical. Samples taken in the adit contained no precious metal values. Samples of quartz from a dump near the shaft had very low precious metal values but contained minor pyrite and arsenopyrite, and rare galena. One sample of quartz float in the creek near the shaft contained 2,350 parts per billion gold.
Workings: The prospect was explored by a 63-foot adit and a now-flooded shaft of uncertain age.
Age: Cretaceous or younger based on the age of the host rock.
Production: No record of production; probably none.
Reserves: None.

Commodities (Major) - Au; (Minor) - As, Pb
Development Status: Undetermined.
Deposit Model: Low-sulfide, gold-quartz vein (Cox and Singer, 1986; model 36a).

Other Databases

Link to USGS - Alaska:	PA011

Other Regions, Features and Areas containing this locality

References