Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Cu; Pb; Zn
Ore minerals chalcopyrite; galena; pyrite; pyrrhotite; sphalerite
Gangue minerals calcite; graphite; quartz; sericite; talc

Geographic location

Quadrangle map, 1:250,000-scale AR
Quadrangle map, 1:63,360-scale A-1
Latitude 67.241
Longitude -156.411
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect is equidistant between the Shungnak and Kogoluktuk Rivers in the NW1/4 Section 10, T. 21 N., R. 11 E., of the Kateel River Meridian. The prospect is at an approximate elevation of 2,600 ft. The location is accurate within 1000 feet.

Geologic setting

Geologic description

The Kogo prospect can be divided into two distinct sequences. The north and east rocks consist predominantly of metasediments and metavolcanics (greenstone). To the south and west a sequence exists consisting of metasediments, carbonate schists, black schists, white schists, marbles, rhyolites. The mineralized occurrence is semi-massive to disseminated sulfides in the metavolcanic schists. The greenstone host rock has been complexly folded and faulted (Ellis, 1980).
The deposit was first discovered in 1974 as a hydrogeochemical anomaly; a copper-precipitating spring was reported to Sunshine Mining Company by R.R. Walters. A white precipitate coated rocks downstream from the spring (Ellis, 1980).
Geologic map unit (, )
Mineral deposit model Kuroko massive sulfide (Cox and Singer, 1986; model 28a).
Mineral deposit model number 28a
Age of mineralization Devonian, based on age of host rock (Ellis, 1980).
Alteration of deposit Quartz, sericite, and pyrite alteration is associated with mineralization (Ellis, 1980).

Production and reserves

Workings or exploration Initial exploration efforts started in the mid-1970s. Exploration efforts included geochemical surveys such as rock, soil, and stream sediment sampling, mapping, geophysical induced polarity (IP) survey, and two shallow exploration diamond core holes. This work was done to determined the cause of the anomalous stream sediments, which was speculated to derive from a deeply buried metalized source. Despite the geophysical work, a mineralized source was not found. A 50 foot mineralized drill section averaged about 0.02 percent silver, 0.05 percent zinc, 0.1 percent copper, and 0.4 percent lead in hole Kogo-1. The majority of this work was completed between 1976 and 1980 by Sunshine Mining Company (Ellis, 1980).
Indication of production None



Ellis, W.T., 1980, Ambler River Project, Alaska, Project Memorandum No. 7, Summary Report of Past Field Investigations and 1980 Field Investigations, Sunshine Mining Company, 114 p. (Report held at Alaska Earth Sciences, Inc., Anchorage, AK).
Reporters A. Angel (Alaska Earth Sciences, Inc.); V.C. Zinno (Alaska Earth Sciences, Inc.)
Last report date 3/11/2014