Mile 4

Prospect, Inactive

Alternative names

Mile Four Mining Co.

Commodities and mineralogy

Main commodities Au
Ore minerals arsenopyrite; chalcopyrite; galena; gold; pyrite; pyrrhotite; sphalerite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale A-7
Latitude 60.1714
Longitude -149.41
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect is located in the SW1/4 section 14, T. 1 N., R. 1 W., of the Seward Meridian. It is situated west of mile four of the Alaska Railroad tracts. This is location 87 of Cobb and Tysdal (1980) and location S-201 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

The prospect consists of stringers and lenses of quartz and calcite as much as 43 inches wide. They strike northeast and dip nearly vertically. The sulfide minerals include arsenopyrite, chalcopyrite, galena, pyrrhotite, pyrite, and sphalerite (Johnson, 1912). Gold occurs free in the quartz and is also associated with the sulfides. Gold assay values ranged from $6.40 to $1.20 per ton (gold value at $20.72 per ounce); the higher values came from smaller lenses, which contained galena, sphalerite, and arsenopyrite (Martin and others, 1915). The host rock is slate and sandstone of the Valdez Group of Late Cretaceous age (Tysdal, 1978 [MF-880-A]). Workings on the prospect in 1911 consisted of a 155-foot adit, a 23-foot inclined shaft 3 feet above the adit, and about 75 feet of surface stripping (Martin and others, 1915).
Geologic map unit (-149.412148513501, 60.1708393658966)
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 Workings on the prospect in 1911 consisted of a 155-foot adit, a 23-foot inclined shaft 3 feet above the adit, and about 75 feet of surface stripping (Martin and others, 1915). Assay results range from $6.40 to $1.20 of gold per ton (gold value at $20.72 per ounce); the higher assay values came from smaller lenses that contained galena, sphalerite, and arsenopyrite (Martin and others, 1915).
Indication of production None

Additional comments

The literature describes this prospect as located at an elevation of 65 feet, but the lowest elevation in the southern half of section 14 is 200 feet.

References

References

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.
Reporters Jeff A. Huber and Carol S. Huber (Anchorage)
Last report date 12/15/2001