Fog

Prospect, Inactive

Alternative names

Steeple Mountain

Commodities and mineralogy

Main commodities Ag; Au
Other commodities As; Cu; Hg; Mo
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-1
Latitude 53.27
Longitude -168.26
Nearby scientific data Find additional scientific data near this location
Location and accuracy
The Fog prospect is located approximately 1 1/2 miles southeast of VABM Ande and may correspond to Christie's (1974) color anomaly 29. The site is part of the Steeple Mountain prospect of Kennecott (Simpson, 1985; Bundtzen and others 1990, locality 25). The site location is accurate to within 1/2 mile.
This site is one of many occurrences or prospects that occur within a 5 square-mile area, mostly within T. 80 S., R. 131 W., of the Seward Meridian. The center of this area is approximately located at VABM Ande.

Geologic setting

Geologic description

This site is similar in character to the Wind prospect (ARDF number UK007) and is marked by a color anomaly measuring approximately 7000 x 4000 feet. Quartz veins are hosted by propylitized volcanic rocks of Tertiary age. The volcanic rocks exhibit localized silicification, especially near the quartz veins.
Some 20 veins thicker than 6 inches were mapped by Battle Mountain Exploraton (Randolph and Ellis, 1989, pg. 21). These generally strike east-west or northwest, and crop out over distances of several hundred feet, although their actual length may be much greater.
The quartz is usually white and contains few visible sulfides. The veins are enriched in arsenic, mercury, and molybdenum and locally in gold and silver. The highest metal values obtained are: 400 ppm arsenic, 107 ppm copper, 8.1 ppm gold, 1600 ppb mercury, 90 ppm molybdenum, 3.4 ounces silver per ton, and 46 ppm zinc (Christie, 1974; Randolph and Ellis, 1989).
Geologic map unit (-168.261974841622, 53.269085416022)
Mineral deposit model Creede epithermal veins? (Cox and Singer, 1986; model 25b)
Mineral deposit model number 25b?
Age of mineralization Late Tertiary or younger.
Alteration of deposit The volcanic rocks exhibit regional propylitic alteration and localized silicification and potassium flooding or secondary growth on primary feldspars. Quartz veins exhibit pyritization and silicification in the surrounding wall rock. Some pyrite-filled fractures show narrow kaolinite-epidote-sericite alteration envelopes. No argillic alteration has been recognized.

Production and reserves

Workings or exploration
In 1975 the Aleut-Quintana-Duval JV did reconnaissance mapping and sampling of this prospect as a followup of the discovery of numerous color anomalies. Analyses of 9 rock samples indicated values of up to 107 ppm copper, <0.01 ppm gold, 6.5 ppm molybdenum, 1.5 ppm silver, and 46 ppm zinc (Christie, 1974).
Kennecott sampled and mapped in this general area in 1985 (Simpson, 1985).
Battle Mountain Exploration in 1989 did detailed mapping, sampling and geophysics at this site. The sampling (141 rock-chip and 87 channel samples) gave values of up to 400 ppm arsenic, 8.1 ppm gold, 1600 ppb mercury, 90 ppm molybdenum, and 3.4 ounces per ton silver (Randolph and Ellis, 1989).
Indication of production None

Additional comments

This site is on land conveyed, patented, or selected by the Aleut Native Corporation.

References

MRDS Number 10308470

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., 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