Niukluk River

Mine, Active?

Commodities and mineralogy

Main commodities Au
Ore minerals gold; pyrite
Gangue minerals garnet; magnetite

Geographic location

Quadrangle map, 1:250,000-scale SO
Quadrangle map, 1:63,360-scale D-4
Latitude 64.902
Longitude -163.732
Nearby scientific data Find additional scientific data near this location
Location and accuracy This mine is a segment of the Niukluk River floodplain that starts at the mouth of Ophir Creek (SO053) and extends 1.3 miles downstream; there is another segment that extends 0.8 miles upstream from Council. These two dredged segments are apparently separated by an unmined segment 0.7 mile long. The lower of the two segments may be slightly elevated with respect to the active floodplain. It is locality 121 of Cobb (1972, MF 445; 1978, OF 78-181).

Geologic setting

Geologic description

Gold was originally discovered on the bars of the Niukluk River in 1865 when a survey crew for a telegraph line passed through the area (Collier and others, 1908). These two areas, with a combined length of 2.1 miles, were extensively dredged over widths up to 2,000 feet. Heavy mineral concentrates from the river contain garnet, pyrite, and magnetite (Collier and others, 1908). The surface elevation varies from about 85 to 150 feet here and the depth to bedrock is not known. Gold was present throughout the gravel but concentrated on bedrock. Some gravels were reported to be thick and bedrock to be at elevations below sea level in what were interpreted to be old river channels (Smith, 1908). The downstream segment included here may be slightly elevated, at the surface, relative to the active floodplain of the river. This part of the Niukluk River is located proximally to the coastal lowlands of Golovin Bay and at low enough elevations to have been influenced by Quaternary sea level fluctuations.
Geologic map unit (-163.734614682824, 64.9012713641952)
Mineral deposit model Placer Au-PGE (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Quaternary; the elevation and location of these placers suggest that they are the result of more than one cycle of erosion and deposition and that sea level fluctuations influenced their development.

Production and reserves

Workings or exploration An area totaling 2.1 miles long and up to 2,000 feet wide, has been dredged, from before WW I to as recently as the 1980s.
Indication of production Yes; small