Francisco

Mine, Inactive

Alternative names

Downing

Commodities and mineralogy

Main commodities Ag; Au
Other commodities Pb; Zn
Ore minerals arsenopyrite; galena; gold
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale D-7
Latitude 60.8263
Longitude -149.5208
Nearby scientific data Find additional scientific data near this location
Location and accuracy The property is located in the SW1/4 section 31, T. 9 N., R. 1 W., of the Seward Meridian. It is situated on the north bank of Bonanza Creek at an elevation of 2,000 feet and is adjacent to the Palmer Creek road. 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 17 of Tysdal (1978 [MF-880-A]), and location S-294 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

The deposit consists of an irregular quartz mass that has a general trend of N70W and a younger quartz vein that heals fractures in the quartz mass. This younger vein strikes approximately north and dips vertically. In places, the vein and quartz mass contain massive arsenopyrite, some galena, and free gold. The vein is rich, but too narrow to be considered minable. The host rock is a massive graywacke of the Valdez Group of Late Cretaceous age (Nelson and others, 1985).
Geologic map unit (-149.522964197176, 60.8257318434356)
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
Workings consist of one 30-foot adit. Improvements include a 0.75-mile-long trail from the Palmer Creek road (Tuck, 1933).
In 1982, U.S. Bureau of Mines examined the Downing mine property, which includes the Francisco (this record), Whistler (SR020), and Bonanza (SR018) properties, and collected two select grab samples and a chip sample (Jansons and others, 1984). These samples assayed nil to 0.39 ounce of gold per ton and nil to 0.3 ounce of silver per ton. The samples were collected on the Whistler prospect (not the Francisco) from the rock dump at the mouth of a 50-foot-long adit.
Indication of production Undetermined
Production notes The U.S. Bureau of Mines reported production of 150 ounces of gold (Jansons and others, 1984). (This might include production from the Whistler (SR020), and Bonanza (SR018) properties as well as the Francisco).

Additional comments

In his description of this deposit, Tuck (1933) also included references to the Whistler (SR020), Bonanza (SR018), and another (unnamed) prospect on Bonanza Creek. 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 2/19/2000