Unnamed (on Cape Kigunak)

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Au
Other commodities As; Cu; Hg; Mo; Zn
Ore minerals chalcopyrite; gold; molybdenite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale UK
Quadrangle map, 1:63,360-scale B-2
Latitude 53.33
Longitude -168.41
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site is located on the west side of Umnak Island on Cape Kigunak, approximately 1 mile east of VABM Kig (Bundtzen and others, 1990, locality 24; Christie, 1974, color anomaly 35). The map site is at an elevation of about 600 feet and is accurate to within 1/2 mile.

Geologic setting

Geologic description

The rocks at this site consist of altered diorite and andesite of Tertiary age, which are overlain by unaltered agglomerate, flows, tuff, and ash of probable Quaternary age (Randolph and Ellis, 1989). The intrusives have been pervasively propylitized and contain localized areas of argillic alteration which in some cases is accompanied by silicification, quartz veining, pyrite, and gold mineralization. The alteration and mineralization are present in minor amounts discontinuously in an area of approximately 2000 by 12,000 feet. The most intense alteration is in the discovery outcrop, which consists of a western zone which is approximately 50 by 200 feet and an eastern zone which measures 25 by 300 feet. These zones are separated by about 100 feet. In these zones the rock has been completely argillized and contains areas of intense silicification and irregular pods of quartz breccia, resulting in a rock composed of finely-banded gold-bearing opaline silica, clay, quartz veins, quartz breccia, and pyrite. The breccia shows evidence of repeated periods of fracturing and healing.
Nineteen surface samples of the discovery zone collected by Kennecott in 1985 gave the following values: gold, 0.005 to 24.3 ppm; silver, 0.2 to 420 ppm; arsenic, 6 to 210 ppm; mercury, 0.12 to 5 ppm (Simpson, 1986, p. 18). Thirty-five surface samples collected elsewhere at this site gave the following ranges in values; gold, 0.1 to 1.55 ppm; silver, 0.2 to 5.7 ppm; arsenic, 4 to 600 ppm; mercury, 0.75 to 3.2 ppm (Simpson, 1986, p. 19). The best values obtained from 5 holes drilled by Kennecott were 21 feet of 0.11 ounce of gold per ton and 5 feet of 0.034 ounce gold per ton. They were not successful in determining the geometry of the alteration/mineralization at the discovery outcrop.
Drilling of 6 holes by Battle Mountain Exploration in 1990 revealed the discovery outcrop to be a part of a tabular quartz breccia zone striking N 32 E and dipping 30-36 to the northwest (Randolph, 1990). The zone ranges in thickness from 20 to 60 feet and has a hanging wall of intensely argillized rock and a footwall of quartz stockwork with argillic alteration.
Detailed channel sampling of surface outcrops revealed an area 70 by 230 feet with gold values greater than 0.02 ounce per ton (Randolph, 1990). Thirty-six channel samples within this zone ranged in values as follows: gold, 0.021 to 2.47 ounces per ton; silver, 0.108 to 2.23 ounces per ton. The best intercepts from the drill core were 15 feet of 0.015 and 11 feet of 0.022 ounce of gold per ton. Core values from the quartz breccia were generally less than 100 ppb gold. The mineralized zone was found to be too small to be of economic significance.
Geologic map unit (-168.411992127032, 53.3290866588236)
Mineral deposit model Hot-spring Au-Ag? (Cox and Singer, 1986; model 25a)
Mineral deposit model number 25a?
Age of mineralization Late Tertiary or younger.
Alteration of deposit The diorite and andesite exhibit pervasive propylitic alteration and localized argillic alteration accompanied by major silicification, quartz veining, brecciation, and gold mineralization.

Production and reserves

Workings or exploration
The first reported visit to this site was in 1974 when the Quintana-Duval joint venture noted it as a color anomaly (number 35). Thirteen rock samples assayed as much as 38 ppm molybdenum, 116 ppm zinc, 1.8 ppm silver, and 0.2 ppm gold (Christie, 1974). The joint venture apparently did not sample the discovery zone.
In 1985 Kennecott conducted geological, geochemical, and geophysical surveys, and drilled 5 holes for a total or 1031 feet (Simpson 1986). Surface sampling of the discovery outcrop ranged in metal values as follows: gold, 0.005 to 24.3 ppm; silver, 0.2 to 420 ppm. The only significant intercepts from the core were 21 feet of 0.11 ounce of gold per ton, 0.24 ounce of silver per ton, and 5 feet of 0.034 ounce of gold per ton.
In 1989-1990 Battle Mountain Exploration Company explored the area (Randolph and Ellis, 1989; Randolph, 1990). They did detailed mapping, sampling and geophysical surveys of the discovery outcrop, and drilled 6 holes. Sampling of the discovery outcrop outlined a zone measuring 70 by 230 with gold values of greater than 0.02 ounce per ton. This zone was found to be too small to be of economic significance. The best drill intercepts were 15 feet of 0.15 and 11 feet of 0.22 ounce of gold per ton. The values in the other holes, which cut the quartz breccia, were generally less than 100 ppb gold.
This prospect was briefly examined and sampled by Amax in 1986 and by Teck in 1994.
Indication of production None

Additional comments

This site is located on land selected by the Aleut Native Corporation.

References

MRDS Number 10308463

References

Christie, J.S., 1974, Aleut-Quintana-Duval 1974 joint venture, final report: Unpublished Quintana Minerals Corporation report, 24 p., 3 appendices, 2 maps. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Randolph, D.B., 1990, Unalaska, 1990 final report: Battle Mountain Exploration Company, 72 p. (Report held by the Aleut Native Corporation, Anchorage, Alaska).
Randolph, D.B., and Ellis, W.T., 1989, Unalaska project, 1989 final report: Battle Mountain Exploration Company, Alaska District, 41 p., 5 appendices, 11 plates, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Simpson, D.F., 1986, Aleutian Islands project, 1985 final report: Kennecott-Alaska Exploration Company, 54 p. (Report held by the Aleut Native Corporation, Anchorage, Alaska).
Reporters S.H. Pilcher (Anchorage)
Last report date 1/27/2000