Free Gold

Occurrences, Undetermined

Commodities and mineralogy

Main commodities Au
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale PA
Quadrangle map, 1:63,360-scale D-4
Latitude 56.96098
Longitude -135.05201
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Free Gold prospect is shown by symbol on the 1:63,360-scale topographic map. It is about 0.6 mile east-northeast of Pinta Lake and about 0.4 mile north of the center of section 5, T. 57 S., R. 66 E.

Geologic setting

Geologic description

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 1940s.
The Free gold prospect was staked in 1876 and an arrastre and mine buildings were built in 1879 (Becker, 1897); Wright and Wright (1905) and Knopf (1912) described the prospect as active but there apparently has been no later work on the prospect. A map by the Edgecumbe Exploration Company shows an adit in the vicinity, but Bittenbender and others (2002) who cite the map could not find the adit. They did find quartz veins in the area that cut massive graywacke. Samples contained low precious metal values; none of the quartz had visible sulfides. But a piece of float collected near the northwest side of the northern of the Lucky Chance Lakes contained 1,180 parts per billion gold.
Geologic map unit (-135.05377221679, 56.9606130406197)
Mineral deposit model Low-sulfide, gold-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Cretaceous or younger based on the age of the host rock.

Production and reserves

Workings or exploration There was considerable work on this prospect prior to 1912 including the construction of an arrastre and several mine buildings. There is no indication of later work other than sampling by government geologists in the late 1990s.
Indication of production None
Reserve estimates None.

Additional comments

MAS number: 0021160010.

References