Hirshey-Lucky Strike

Mine, Inactive

Alternative names

Lucky Strike
Swetmann

Commodities and mineralogy

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

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale D-7
Latitude 60.7753
Longitude -149.5529
Nearby scientific data Find additional scientific data near this location
Location and accuracy The mine is located in the NW1/4 section 24, T. 8 N., R. 2 W., of the Seward Meridian. The mill site is located on the east side of Palmer Ceek near the head of Palmer Creek valley, at an elevation of 2,200 feet. The mine workings are located about three-fourths of a mile south of the mill site at between 3,200 and 3,400 feet elevation. This is location 12 of Cobb and Richter (1972), location 11 of MacKevett and Holloway (1977), location 24 of Cobb and Tysdal (1980), and location S-289 of Jansons and others (1984). This location is accurate to within 300 feet.

Geologic setting

Geologic description

The country rock in this area is slate of the Valdez Group of Late Cretaceous age (Nelson and others, 1985). The slate strikes N35E and dips 60-80E. Near the surface the slate dips as low as 40E due to surface creep. Bedding in the slate is not visible underground (Hoekzema and Sherman, 1983).
The underground workings consist of three levels at vertical intervals of 100 feet. The upper adit is about 30 feet below the discovery outcrop and is collapsed. This adit was about 350 feet in length. The middle adit was about 500 feet long; it is unsafe to enter because the ground above and below the adit has been stoped out. The lower adit was about 600 feet long and is collapsed about 100 feet from the portal (Hoekzema and Sherman, 1983).
The deposit consists chiefly of an auriferous, sulfide-bearing, quartz-carbonate vein. Parts of the vein are oxidized and sheared. The vein occurs in a curving and branching fracture that cuts perpendicularly across the cleavage of the slate, so that the strike of the vein ranges from N45W to west. The dip of the vein ranges from 20N on the west end of the middle level to 75NE on the east end of the middle level. The average dip is about 40N. The width of the vein ranges from a few inches to 5 feet and averages about 18 inches. On the lower level the vein is about 300 feet long, but only locally contains ore minerals. On the middle level, the vein is 350 feet long; the vein is shorter on the upper level due to the slope of the hill (Tuck, 1933). The vein contains considerable fault gouge and, in part, consists of breccia that has been healed by quartz. Considerable post-mineral movement has taken place; most of the movement is parallel to the vein margins. The margins of the vein are clearly defined, and the quartz breaks cleanly from the sheared slate (Tuck, 1933).
The mineralogy of the vein consists of quartz along with small amounts of calcite and ankerite. The metallic minerals, in order of abundance, are arsenopyrite, pyrite, galena, sphalerite, chalcopyrite, and free gold. Arsenopyrite is by far the most abundant sulfide. The proportion of sulfide to quartz varies greatly from place to place, ranging from less than 1 percent to more than 20 percent (Tuck, 1933). There does not appear to be a direct relation between sulfide content and gold grade. In fact, the richest gold ore appears to have the lowest sulfide content (Tuck, 1933). The gold is almost entirely in the principal vein. In some of the richer parts of the mine, other veins in the wallrock may carry some gold, but not enough to warrant mining. Assays were as high as several hundred dollars in gold per ton (gold at $20.67 per ton). The upper portion of the mine was rich enough to make a profit using a one-stamp mill. In general, the oxidized and sheared quartz, which can easily be identified by eye, carries the highest values (Tuck, 1933).
Geologic map unit (-149.555058360846, 60.77472337052)
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
The deposit that became the mine was discovered in 1911 by John Hirshey. A one-stamp mill was built on the site, and the mine operated from 1911 to 1921, when it was sold to the Anchorage Mining Company. In 1921, a road was built from Hope to the mine site, and a new plant consisting of a jaw crusher, a five-stamp mill with amalgamator plate, and a Wilfley table was built. The mine was productive until 1927, when it reverted back to John Hirshey, who sporadically mined until 1940. In 1931 a cyanide plant was used to rework tailings but was unsuccessful (Tuck, 1933). There has been no further production since 1940.
The underground workings consist of three levels at vertical intervals of 100 feet. The upper adit is about 30 feet below the discovery outcrop and is collapsed. This adit was about 350 feet in length. The middle adit was about 500 feet long; it is unsafe to enter as the ground above and below the adit has been stoped out . The lower adit was about 600 feet long and is collapsed about 100 feet from the portal (Hoekzema and Sherman, 1983).
Indication of production Yes; small
Reserve estimates The U.S. Bureau of Mines estimated a resource of 2,000 tons with an estimated grade of 1 to 1.25 ounces of gold per ton and 0.65 ounce of silver per ton (Hoekzema and Sherman, 1983).
Production notes Total production from this mine is 6,094 ounces of gold and 4,699 ounces of silver from about 8,706 tons of ore (Hoekzema and Sherman, 1983).

Additional comments

Tuck (1933) stated that the vein continued below the lower level, but the deposit has never been drilled below the lower working. In addition, the 0.3 ounce of gold per ton cut-off grade in the old workings suggests that a potential gold resource may remain.

References

References

Garrett, C.R., 1972, Grant Lake Development Co. report of mineral examination: U.S. Forest Service; held at the Chugach National Forest office, Anchorage, 19 p.
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
Smith, S.S., 1917, The mining industry in the Territory of Alaska during the calendar year 1915: U.S. Bureau of Mines Bulletin 142, 65 p.
Reporters Jeff A. Huber (Anchorage)
Last report date 4/29/2000