Quadrangle map, 1:250,000-scale | SR |
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Quadrangle map, 1:63,360-scale | C-7 |
Latitude | 60.6447 |
Longitude | -149.2952 |
Nearby scientific data | Find additional scientific data near this location |
Location and accuracy | This prospect is at an elevation of 4,250 feet on the divide betwee the two forks of Groundhog Creek. It is located in the NW1/4 section 4, T. 6 N., R. 1 E., of the Seward Meridian. This location is accurate to within a quarter of a mile. This is location 35 of Cobb and Richter (1972), location 24 of MacKevett and Holloway (1977), location 36 of Cobb and Tysdal (1980), and location S-268 of Jansons and others (1984). |
Geologic descriptionThe deposit consists of auriferous, sulfide-bearing, quartz-calcite veins that fill fractures in a shear zone in slate of the Valdez Group of Late Cretaceous age. The zone is 5 to 6 feet wide and extends S80E between two pale-greenish porphyritic dikes (Johnson, 1912). Much of the quartz is coarsely crystalline and is accompanied by a small amount of calcite, along with arsenopyrite, galena, sphalerite, and gold. The vein material is weathered and decomposed and has been traced about a hundred feet. The vein dips steeply south, nearly vertically. A narrow streak of fault gouge lies along the hanging wall at the shear zone. The gold is free-milling or in the arsenopyrite and galena. Specimens from the outcrop contain visible free gold (Johnson, 1912). The workings on this prospect consist of trenches and a 90-foot adit with 23 feet of winzes, a 12-foot crosscut, and a 15-foot shaft (Johnson, 1912). The adit collapsed in 1911 (Martin and others, 1915). | |
Geologic map unit | (-149.297323162649, 60.6441187688884) |
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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. |
Workings or exploration |
The workings on this prospect consist of trenches and a 90-foot adit with 23 feet of winzes, a 12-foot crosscut, and a 15-foot shaft (Johnson, 1912). The adit collapsed in 1911 (Martin and others, 1915). The U.S. Bureau of Mines examined the prospect and collected samples in 1981. Two chip samples assayed a trace and 0.02 ounces of gold per ton, and a trace and 0.23 ounces of silver per ton. Two selected grab samples assayed 0.79 and 0.99 ounce of gold per ton, and 0.08 and 0.46 ounce of silver per ton. A grab sample of dump material contained a trace of gold and 0.02 ounce of silver per ton (Jansons and others, 1984). |
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Indication of production | None |
MRDS Number | A010525 |
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ReferencesHoekzema, 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.
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Reporters | Jeff A. Huber (Anchorage) |
Last report date | 1/25/2000 |