Reynolds-Alaska Development Co.

Prospect, Inactive

Commodities and mineralogy

Main commodities Cu
Other commodities Ag; Zn
Ore minerals chalcopyrite; pyrrhotite; sphalerite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale CV
Quadrangle map, 1:63,360-scale D-7
Latitude 60.869
Longitude -146.561
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is at an elevation of about 1700 feet, approximately 0.75 mile northeast of Copper Mountain. It is in S1/2 sec. 36, T. 11 S., R. 8 W., of the Copper River Meridian. The location is accurate to within 1000 ft. This prospect is shown as #12 in Cobb (1972: MF-392) and as C-79 in Jansons and others (1984).

Geologic setting

Geologic description

The country rocks at this prospect are mafic volcanic rocks and sedimentary rocks of the Tertiary Orca Group (Nelson and others, 1985). The deposit consists of chalcopyrite, pyrrhotite, and sphalerite in a 1-to 20- foot-wide shear zone in volcanic rocks (Capps and Johnson, 1915).
Capps and Johnson (1915) reported assays of 11.4 to 12.5% Cu and 0.18 oz Au and 0.26 oz Ag per ton. Later development included four adits with about 820 ft. of underground workings and some open cuts. Three of the adits are caved or flooded (Jansons and others, 1984). Chip samples from the open cuts contained 0.18% to 8.4% Cu, 170 ppm to 0.25% Zn, and 0.8 ppm to 28 ppm Ag (Jansons and other, 1984). Grab samples gave the following values: 100 ppm to 9.75% Cu, 100 ppm to 1.05% Zn, and 0.8 ppm to 9.5 ppm Ag.
Geologic map unit (-146.562996053945, 60.8684524054355)
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 Site was discovered in 1899 and by 1912 there were 900 feet of underground workings. Capps and Johnson (1915) reported assays of 11.4 to 12.5 % Cu; and 0.18 oz Au and 0.26 oz Ag per ton. Later development included four adits with about 820 ft. of underground workings and some open cuts. Three of the adits are caved or flooded (Jansons and others, 1984). Chip samples from the open cuts contained 0.18% to 8.4% Cu, 170 ppm to 0.25% Zn, and 0.8 ppm to 28 ppm Ag (Jansons and other, 1984); Grab samples gave the following values: 100 ppm to 9.75% Cu, 100 ppm to 1.05% Zn, and 0.8 ppm to 9.5 ppm Ag.
Indication of production None
Reserve estimates Inferred reserves of 3000 tons @ 4.6% Cu, 0.14% Zn, and 15.65% Ag (Jansons and others, 1984).

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 A010433

References

Reporters S.W. Nelson, Anchorage, AK
Last report date 6/10/2000