Gilpatrick

Prospect, Inactive

Alternative names

Frenchy Creek

Commodities and mineralogy

Main commodities Ag; Au
Other commodities Cu; Pb; Zn
Ore minerals arsenopyrite; chalcopyrite; galena; gold; malachite; sphalerite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale C-7
Latitude 60.7315
Longitude -149.5031
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is located in the NW1/4 section 5, T. 7N., R. 1 W., of the Seward Meridian. It is situated on the east end of the divide between Frenchy and Pass Creeks, at an elevation of 3,000 feet. The location is accurate to within a quarter of a mile. This is location 19 of MacKevett and Holloway (1977), location 31 of Cobb and Tysdal (1980), and location S-275 of Jansons and others (1984).

Geologic setting

Geologic description

The deposit consists of auriferous, sulfide-bearing, quartz-carbonate veins and pods that heal fractures in an Eocene(?) felsic dike (Hoekzema and Sherman, 1983). The dike, which intrudes slate and graywacke of the Valdez Group of Late Cretaceous age (Nelson and others, 1985), averages 16 feet wide at the discovery. The quartz bodies are as much as 10 feet wide and contain arsenopyrite, chalcopyrite, galena, and sphalerite. Arsenopyrite also occurs in the dike rock. Malachite staining occurs locally. The sedimentary country rock strikes N15E and dips steeply west; the dike strikes N10E and dips 30 to 50W, the dip increasing with depth (Hoekzema and Sherman, 1983). The dike extends from a point on the north side of Frenchy Creek southward to the Pass Creek drainage basin (Tuck, 1933).
Geologic map unit (-149.505245623451, 60.7309161325687)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Eocene(?) or younger; the age of felsic dike host rock is Eocene?

Production and reserves

Workings or exploration
The workings on this prospect consist of a 50-foot inclined (30 degrees) shaft with a caved winze at the bottom, prospect pits, and trenching (Hoekzema and Sherman, 1983).
The U.S. Bureau of Mines collected surface and subsurfaces samples in 1979 (Hoekzema and Sherman, 1983). A selected dump sample assayed 0.42 ounce of gold per ton and 24.21 ounces of silver per ton. Three chip samples from the incline assayed a trace of gold and 0.02 to 0.22 ounce of silver per ton (Jansons and others, 1984).
Indication of production None

Additional comments

Tuck (1933) suggests that the dike is probably a continuation of the dike that occurs to the south; see, for example, the Gilpatrick Dike mine, SR136.

References

MRDS Number A010386

References

Reporters Jeff A. Huber (Anchorage)
Last report date 3/5/2000