Ochre

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Pb; Zn
Other commodities As; Au; Hg; Sb
Ore minerals chalcopyrite; galena; pyrite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale PM
Quadrangle map, 1:63,360-scale A-2
Latitude 55.247
Longitude -160.609
Nearby scientific data Find additional scientific data near this location
Location and accuracy The map site of the Ochre prospect is at an elevation of 800 feet, in the NW1/4 of sec. 13, T. 57 S., R. 75 W., Seward Meridian, approximately 2 miles northwest of Baralof Bay on Unga Island. The site is 0.35 mile west-northwest of a 655-foot-high hillock. The location is accurate to within 1,200 feet.

Geologic setting

Geologic description

This prospect consists of northeast-striking silicified breccia zones and northwest-striking quartz veins. Chalcopyrite, galena, and sphalerite occur sporadically in the breccia and the veins. The host rock is silicified and argillized pyritic andesite of the late Eocene to early Oligocene Popof volcanic rocks (Wilson and others, 1995).
The main silicified breccia is 5 to 15 feet in width and strikes N 25 to 65 E. Assays show as much as 18 ppm silver, 450 ppm copper, 3,500 ppm lead, 5,400 ppm zinc, 1,080 ppm arsenic, and 118 ppm mercury (Anderson and others, 1980).
Float samples of the northwest-striking vein system assayed as much as 0.51 ppm gold, 72 ppm silver, 3,100 ppm lead, 6,100 ppm zinc, 285 ppm arsenic, 108 ppm mercury, and 6,200 ppm antimony.
Battle Mountain Exploration Company sampled the site in 1990. None of the samples taken contained significant gold values.
Geologic map unit (-160.611040573832, 55.2461703521082)
Mineral deposit model Epithermal gold vein
Age of mineralization Eocene or younger.
Alteration of deposit The host rock is variously argillized, silicified, and pyritized.

Production and reserves

Workings or exploration
In 1980 Resource Associates of Alaska mapped the prospect, collected 504 soil and 152 rock samples, and conducted VLF-EM and magnetometer surveys (Anderson and others, 1980). Float samples of vein quartz contained as much as 0.51 ppm gold and 72 ppm silver and anomalous amounts of copper, lead, zinc, arsenic, mercury, and antimony.
Battle Mountain Exploration Company sampled the site in 1990. The samples contained no gold values of note.
Indication of production None

Additional comments

This prospect is located on land patented by, or interim-conveyed to, the Aleut Corporation.

References

MRDS Number 10308133

References

Andersen, G.D., Butherus, D.L., Fankhauser, R.E., Pray, J.C., Lindberg, P.A., and Hoffman, B.L., 1980, Exploration and evaluation of lands leased from Aleut Native Corporation 1980: Resource Associates of Alaska Report, 84 p, 16 map sheets, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Ellis, W.T., and Apel, R.A., 1990, Unga/Alaska Peninsula 1990 final report: Battle Mountain Exploration Company report, 49 p., 29 map sheets at various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Reporters S.H. Pilcher
Last report date 2/4/2001