Fielder & Hemple

Prospect, Inactive

Commodities and mineralogy

Main commodities Cu; Zn
Other commodities Ag; Au
Ore minerals chalcopyrite; pyrite; pyrrhotite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale CV
Quadrangle map, 1:63,360-scale D-7
Latitude 60.858
Longitude -146.54
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is at an elevation of about 700 ft. on the north side of inner Landlocked Bay, and about 0.5 mile north of VABM Dick. It is in the W1/2 sec. 6, T. 12 S., R. 7 W., of the Copper River Meridian. The site location is accurate to within 1000 ft. This location corresponds to site C-74 in Jansons and other (1984) and to #14 in Cobb (1972: MF-392).

Geologic setting

Geologic description

The deposit at this prospect is in mafic volcanic and sedimentary rocks of the Tertiary Orca Group (Nelson and others, 1985). It consists of a 24-foot-wide shear zone in pillow basalts and slates that contains small masses of sulfides and quartz as well as sulfide-rich stringers. The zone is traceable for at least 1,500 feet along strike (Capps and Johnson, 1913). The sulfide minerals are chalcopyrite, pyrite, and pyrrhotite.
Sampling by Mihelich and Wells (1957) gave the following results: five chip samples from the 1200 ft. adit contained less than 0.1 to 1.1 percent Cu, less than 0.1 to 1.3 percent Zn, trace to 0.32 oz. Au/ton, and 0.02 to 0.32 oz. Ag/ton. Sampling by Jansons and others (1984) gave the following results: five chip samples contained 0.19 to 2.6 percent Cu, 800 ppm to 0.7 percent Zn, 2.6 ppm to 3.7 ppm Ag, and less than 0.03 ppm to 0.12 ppm Au. Selected grab samples contained 4.5 percent and 4.6 percent Cu, 1.7 percent and 1.8 percent Zn, 4.1 ppm and 13 ppm Ag, and 0.06 ppm and 3.1 ppm Au.
Geologic map unit (-146.541992965757, 60.8574514768256)
Mineral deposit model Cyprus massive sulfide (Cox and Singer, 1986; model 24a)
Mineral deposit model number 24a
Age of mineralization Probably Tertiary based on the age of the host rocks.

Production and reserves

Workings or exploration Capps and Johnson (1913) reported four adits having the following lengths: 1200 ft., 250 ft., 65 ft., and 18 ft. There were also minor surface workings. Only two adits could be found during later exploration (Jansons and others, 1984). Sampling by Mihelich and Wells (1957) gave the following results: five chip samples from the 1200 ft. adit contained less than 0.1 to 1.1 percent Cu, less than 0.1 to 1.3 percent Zn, trace to 0.32 oz. Au/ton, and 0.02 to 0.32 oz. Ag/ton. Sampling by Jansons and others (1984) gave the following results: five chip samples contained 0.19 to 2.6 percent Cu, 800 ppm to 0.7 percent Zn, 2.6 ppm to 3.7 ppm Ag, and less than 0.03 ppm to 0.12 ppm Au. Selected grab samples contained 4.5 percent and 4.6 percent Cu, 1.7 percent and 1.8 percent Zn, 4.1 ppm and 13 ppm Ag, and 0.06 ppm and 3.1 ppm Au.
Indication of production Yes; small
Reserve estimates Inferred reserves ( Mihelich and Wells, 1957) are 6,300 tons @ 1.3% Cu.

Additional comments

Nelson and others (1985) interpret the country rocks as accreted ocean crust. Crowe and others (1992; 1993) and Sainsbury (1993) discuss the genesis of the volcanogenic massive sulfide deposits in this area.
Chugach Alaska Corporation, Anchorage, Alaska has control of these lands.

References

MRDS Number A010423

References

Sainsbury, C.L., 1993, Geology and geochemistry of volcanogenic massive sulfide deposits and related igneous rocks, Prince William Sound, south-central Alaska, A discussion: Economic Geology, v. 88, p. 1284-1285.
Reporters S.W. Nelson, Anchorage, AK
Last report date 6/10/2000