| Quadrangle map, 1:250,000-scale | PM |
|---|---|
| Quadrangle map, 1:63,360-scale | A-2 |
| Latitude | 55.241 |
| Longitude | -160.629 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | This prospect is located on Unga Island approximately 3 miles west of the Squaw Harbor cannery on Baralof Bay (Wilson and others, 1988, locality 43). The map site is at an elevation of about 750 feet, about 0.15 mile southwest of the center of sec. 14, T. 57 S., R. 75 W., of the Seward Meridian. The location is accurate to within 1,000 feet. |
Geologic descriptionThis prospect is a linear, northeast-striking stockwork of reticulated, gossanous, multistage quartz veins in intensely brecciated and silicified andesite and rhyolite tuffs. The stockwork is 1,800 feet long and as much as 600 feet wide. The host rocks are part of the late Eocene to early Oligocene Popof volcanic rocks (Wilson and others, 1995). Silicification is most intense in a 50- to 100-foot-wide zone on the northwest side of the stockwork. The quartz veins contain pods and lenses of barite and variable amounts of galena, pyrite,and sphalerite (Peterson and others, 1982). In the area east of the stockwork, the country rocks are highly fractured and partly silicified and argillized.
Channel samples contained as much as 2.35 ppm gold, 19.0 ppm silver, 5,700 ppm lead, 1,305 ppm zinc, 346 ppm copper, 5 ppm or more mercury, and 320 ppm arsenic. Grab samples contained as much as 0.585 ppm gold, 21 ppm silver, 4,000 ppm lead, 6,160 ppm zinc, 705 ppm copper, 5 ppm or more mercury, and 1,000 ppm or more arsenic (Peterson and others, 1983). Antimony, tellurium, and thallium are also present. The highest values in drill core were 1.41 ppm gold and 47 ppm silver (Wilson and others, 1988). Battle Mountain Exploration Company examined and sampled this site in 1990. Thirty-two samples of vein material all contained less than 0.1 ppm gold. Two samples of pyritic and argillically-altered rock from the footwall contained 0.444 and 0.459 ppm gold. Arsenic values commonly exceeded 100 ppm and mercury values exceeded 1 ppm (Ellis and Apel, 1990). | |
| Geologic map unit | (-160.631047338436, 55.2401689460186) |
|---|---|
| Mineral deposit model | Epithermal gold veins, Polymetallic veins (Cox and singer, 1986; model 22c) |
| Mineral deposit model number | 22c |
| Age of mineralization | Eocene or younger. |
| Alteration of deposit | The rocks at this prospect exhibit strong silicification and some argillization. |
| Workings or exploration |
Resource Associates of Alaska and UNC Teton Exploration Drilling Company explored on this prospect from 1979 to 1983. They collected 100 rock, 134 core, and 81 channel samples; conducted VLF-EM surveys; cut 380 feet of trenches; and drilled two core holes for a total of 776 feet.
The highest precious metal values are: channel samples, 2.35 ppm gold and 19 ppm silver; grab samples, 0.585 ppm gold and 21 ppm silver; drill core, 1.41 ppm gold and 47 ppm silver. In 1990 Battle Mountain Exploration Company collected 32 vein samples, all of which contained less than 0.1 ppm gold. Two altered and pyritic wall rock samples contained 0.444 and 0.459 ppm gold. |
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| Indication of production | None |
Additional commentsThis site is on land patented by, or interim-conveyed to, the Aleut Corporation. | |
| MRDS Number | 10308134 |
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ReferencesEllis, 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.)
Peterson, R.J., Handverger, P., Rosenkrans, D., Bartels, E, and Woolston, D., 1983, Shumagin Islands precious metal exploration program southwest Alaska: UNC Teton Exploration Drilling Company report, 61 p. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Peterson, R.J., Lemmers, J., Handverger, P., Gallagher, J., Pilcher, R., East, J., Macleod, T., Bartels. E., 1982, Geology and precious metals potential Unga, Popof, and Korovin Islands, Shumagin Group, Aleutian Chain, Alaska: UNC Teton Exploration Drilling Company report, 127 p., 5 map sheets, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)
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| Reporters | S.H. Pilcher |
| Last report date | 1/15/2001 |