Northwest Fork of Coghill River

Occurrence, Inactive

Commodities and mineralogy

Main commodities Au
Ore minerals gold

Geographic location

Quadrangle map, 1:250,000-scale AN
Quadrangle map, 1:63,360-scale A-2
Latitude 61.14
Longitude -147.74
Nearby scientific data Find additional scientific data near this location
Location and accuracy Northwest fork of the Coghill River (north of Coghill Lake). Accurate within 2 miles. Locality P-38 of Jansons and others (1984) and locality P-32 of Hoekzema and Fechner (1986).

Geologic setting

Geologic description

According to Jansons and others (1984), gold is found in thin, poorly to moderately sorted alluvial gravels and concentrated on and in slate bedrock exposed in the canyon of the northwest fork of Coghill River. A small amount of gravel occurs in the canyon, but a substantial amount has accumulated above its junction with the main fork of the Coghill River.
Three alluvium samples contained 0.0004 to 0.0063 oz Au/cubic yard. Gold nuggets up to 1/16 in diameter was recovered (Jansons and others, 1984).
Geologic map unit (-147.742029622439, 61.1394552958349)
Mineral deposit model Placer Au (Cox and Singer, 1986; model 39a)
Mineral deposit model number 39a
Age of mineralization Quaternary.

Production and reserves

Workings or exploration Three alluvium samples contained 0.0004 to 0.0063 oz Au/cubic yard. Gold up to 1/16 in diameter was recovered. Considerable arsenopyrite was also recovered (Jansons and others, 1984).
Indication of production None
Production notes There is no recorded production, however Hoekzema and Fechner (1986) report the potential for mineral development to be moderate for suction dredging. The grades are low to marginal, but there is a good possibility of identifying local economic concentrations of gold.

References

MRDS Number A106194

References

Reporters D.P. Bickerstaff (USGS contractor); S.W. Huss (USGS)
Last report date 7/30/1998