Bonanza

Prospect, Inactive

Alternative names

Downing

Commodities and mineralogy

Main commodities Au
Other commodities Ag
Ore minerals arsenopyrite; gold; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale D-7
Latitude 60.8243
Longitude -149.5205
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Bonanza prospect in the Downing mine area (see additional comments). The prospect is at an elevation of about 2,100 feet on the north bank of Bonanza Creek. It is in the S1/2 section 31, T. 9 N., R. 1 W., of the Seward Meridian. The Bonanza prospect is located about half way between the Francisco (SR017) and Whistler (SR020) properties. This is location 9 of Cobb and Richter (1972), location 8 of MacKevett and Holloway (1977), locations 17, 19, and 20 of Cobb and Tysdal (1980), location 19 of Tysdal (1978 [MF-880-A]), and location S-294 of Jansons and others (1984). The location is accurate to within half a mile.

Geologic setting

Geologic description

This deposit consists of a 6 foot width of 2- to 3-inch-wide quartz stringers parallel to schistose slate of the Valdez Group of Late Cretaceous age (Nelson and others, 1985). The stringers contain a little arsenopyrite and pyrite. In addition to the stringers, there is abundant vuggy quartz float (Tysdal, 1978 [MF-880-A]). Tuck (1933) sampled the stringer lode, but the assays showed only traces of gold and silver.
Geologic map unit (-149.522663818584, 60.8237314899651)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Cretaceous or younger; the veins cut rocks of the Valdez Group of Late Cretaceous age.

Production and reserves

Workings or exploration The veins are exposed by prospect pits, and there may be a caved adit (Tysdal, 1978 [MF-880-A]). Tuck (1933) sampled across the vein stringers, but the assays indicated only traces of gold and silver.
Indication of production Undetermined
Production notes The U.S. Bureau of Mines reported a recorded production of 150 ounces of gold (Jansons and others, 1984). This might include production from the Whistler (SR020) and Francisco (SR017) prospects, as well as the Bonanza.

Additional comments

In his description of this deposit, Tuck (1933) also included references to the Whistler (SR020), Francisco (SR017), and to another (unnamed) prospect on Bonanza Creek. The Bonanza property is about halfway between the Francisco and Whistler properties. The Francisco, Whistler, and Bonanza are also known as the Downing mine (Jansons and others, 1984). Tysdal (1978 [MF-880-A]) considered these to be separate prospects.

References

References

Hoekzema, R.P., and Sherman, G.E., 1983, Mineral investigations in the Chugach National Forest, Alaska (Peninsula study area): U.S. Bureau of Mines in-house report; held at U.S. Bureau of Land Management Alaska State Office, Anchorage, 524 p.
Mitchell, P.A., 1979, Geology of the Hope-Sunrise (gold) mining district, north-central Kenai Peninsula, Alaska: Stanford University Master of Science thesis, 123 p.
Reporters Jeff A. Huber (Anchorage)
Last report date 2/20/2000