Fidalgo-Alaska

Mine, Inactive

Alternative names

Schlosser

Commodities and mineralogy

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

Geographic location

Quadrangle map, 1:250,000-scale CV
Quadrangle map, 1:63,360-scale D-7
Latitude 60.774
Longitude -146.417
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Fidalgo-Alaska mine is at an elevation of about 500 feet, about 0.8 mile east of the mouth of Irish Cove and 0.5 mile north of peak 1430. It is in the NW1/4 sec. 2, T. 13 S., R. 7 W., of the Copper River Meridian. The site is accurately located to within 1000 ft. This mine is shown as site C-28 in Jansons and others (1984) and site #19 in Cobb (1972: MF-392).

Geologic setting

Geologic description

This deposit consists of sulfide-bearing quartz-calcite veins in 150- to 300-foot-wide shear zones in folded and sheared slate and graywacke of the Tertiary Orca Group (Nelson and others, 1985). The sulfide minerals include chalcopyrite, pyrite, pyrrhotite, and sphalerite.
This mine was developed and productive from 1913 to about 1920 (Cobb, 1979: OF 79-973). Five adits with the following lengths are reported (Jansons and others, 1984): 1800 ft., 540 ft., 410 ft., 250 ft., and 50 ft. U.S Bureau of Mines samples from various adit levels and of surface materials contained 0.02 percent to 19.5 percent Cu, 150 parts per million (ppm) to 29 percent Zn, 2 ppm to 15 ppm Ag, and <0.02 ppm to 5.8 ppm Au. Industry evaluation of the property was undertaken in 1986 (B. Ellis, personal communication, 2000).
A grab sample taken in 2014 contained 1.095 ppm Au, 11.55 ppm Ag, 1.84 percent Cu, and 0.086 percent Zn (Angel, 2014).
Geologic map unit (-146.418972060787, 60.7734445123454)
Mineral deposit model Besshi massive sulfide (Cox and Singer, 1986; model 24b)
Mineral deposit model number 24b
Age of mineralization Early Tertiary age based on the age of the host rocks (Nelson and others, 1985).
Alteration of deposit Oxidation of copper minerals (Angel, 2014).

Production and reserves

Workings or exploration
This mine was developed and productive from 1913 to about 1920 (Cobb, 1979: OF 79-973). Five adits with the following lengths are reported (Jansons and others, 1984): 1800 ft., 540 ft., 410 ft., 250 ft., and 50 ft. U.S Bureau of Mines samples from various adit levels and of surface materials contained 0.02 percent to 19.5 percent Cu, 150 parts per million (ppm) to 29 percent Zn, 2 ppm to 15 ppm Ag, and <0.02 ppm to 5.8 ppm Au. Industry evaluation of the property was undertaken in 1986 (B. Ellis, personal communication, 2000).
Field work including sampling was performed in 2014. A grab sample taken in 2014 contained 1.095 ppm Au, 11.55 ppm Ag, 1.84 percent Cu, and 0.086 percent Zn (Angel, 2014).
Indication of production Yes; small
Reserve estimates Jansons and others (1984) report indicated reserves of 25,625 tons at 3 percent Cu and inferred reserves of 224,000 tons at 3.18 percent Cu.
Production notes 4,160,820 lbs. Cu and 1,384 oz Ag were produced from 21,434 tons of ore. Average grade was 10 percent Cu.

Additional comments

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 10307363

References

Angel, A.K., 2014 Mineral Assessment of Chugach Alaska Lands, Unpublished Report, 21p. (Report held by Chugach Alaska Corporation, Anchorage, Alaska).
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; A.K. Angel (Alaska Earth Sciences, Inc.)
Last report date 9/9/2014