Golden Fleece (Emerald Lake)

Prospect, Probably inactive

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Cu
Ore minerals limonite
Gangue minerals clay minerals; quartz

Geographic location

Quadrangle map, 1:250,000-scale IL
Quadrangle map, 1:63,360-scale B-5
Latitude 59.3031
Longitude -154.7608
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Golden Fleece (or Emerald Lake) prospect is about 2 miles west of Emerald Lake. For this record, the prospect is about at the midpoint of the south boundary of sec. 13, T. 10 S., R. 33 W., Seward Meridian. The location is accurate for the center of the mineralized area.

Geologic setting

Geologic description

This prospect consists of several quartz veins that cut the Oligocene to Pliocene Gibraltar Lake volcanic formation. From the base up, the formation consists of rhyolite lithic-crystal tuff, andesite flows, and rhyolitic ash-flow tuff (Detterman and Reed, 1980; Butherus and others, 1981). The formation is underlain by older Tertiary tuff and overlain by the mesa-forming Intricate Basalt. Butherus and others (1981) propose that the source of the Gibraltar Lake volcanic rocks may be a vent on hill 2349 about 2.5 miles south of the prospect.
Butherus and others (1981) mapped eight vuggy, coxcomb-quartz veins in rubble crop on the upper ash-flow tuff member of the Gibraltar Lake formation. The wall rocks of the veins are intensely argillized. The veins do not contain visible gold or sulfides, but the quartz is coated with limonite, suggesting the presence of at least small amounts of pyrite or other sulfides before weathering. Samples of highly altered ash-flow tuff in the wallrocks of the veins assayed 0.1 to 0.9 parts per million (ppm) gold, and two samples contained anomalous amounts of silver and copper (Butherus and others, 1981). Pan concentrates of soils in the prospect area contained as much as 7.6 ppm gold. Pan concentrates collected along the incised, north-trending canyon in section 13 that drains the prospect area locally assayed as much as 7.8 ppm gold (Anderson and others, 1979).
Anderson and others (1979) and Butherus and others (1981) believe that this deposit is similar to the one at the KUY prospect (IL035), namely that both are epithermal, low-sulfide gold systems.
Geologic map unit (-154.762938130984, 59.3024104998534)
Mineral deposit model Low-sulfide gold-quartz veins (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Tertiary (Pliocene?).
Alteration of deposit Silicification of tuff; locally intense argillization of wall rock near veins. Locally conspicuous oxidation of deposit.

Production and reserves

Workings or exploration
The prospect area is marked by a a strong color anomaly developed on the intensely altered rocks. The prospect was discovered by geologists of Resource Associates of Alaska (RAA), who collected rock, soil, and stream- sediment samples (Anderson and others, 1979; Butherus, 1981).
Samples of highly altered ash-flow tuff in the wallrocks of the veins assayed 0.1 to 0.9 parts per million (ppm) gold, and two samples contained anomalous amounts of silver and copper (Butherus and others, 1981). Pan concentrates of soils in the prospect area contained as much as 7.6 ppm gold. Pan concentrates collected along the incised, north-trending canyon in section 13 that drains the prospect area locally assayed as much as 7.8 ppm gold (Anderson and others, 1979).
Indication of production None

References

References

Anderson, Gary, and others, 1979, The mineral potential of the Bristol Bay Native region, v. II, book 4: Resource Associates of Alaska, Fairbanks, Alaska (Report on file, Bristol Bay Native Corporation, Anchorage, Alaska).
Butherus, D. L, White, D. C., Smith, W. H., Radford, Geoff, Sandberg, R. J., and Pray, J. C., 1981, Exploration and evaluation of precious metals potential of Bristol Bay Native Corporation lands, southwest Alaska, v. 1: Resource Associates of Alaska, Fairbanks, Alaska. (Report on file, Bristol Bay Native Corporation, Anchorage, Alaska).
Reporters C.C. Hawley, Hawley Resource Group, Anchorage, Alaska
Last report date 6/18/2003