| Main commodities | Au |
|---|---|
| Other commodities | Ag; Cu; Pb; Zn |
| Ore minerals | arsenopyrite; chalcopyrite; galena; gold; pyrrhotite; sphalerite |
| Gangue minerals | quartz |
| Quadrangle map, 1:250,000-scale | SR |
|---|---|
| Quadrangle map, 1:63,360-scale | C-4 |
| Latitude | 60.7372 |
| Longitude | -148.176 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | This mine is located in the SW1/4 section 35, T. 8 N., R. 7 E., of the Seward Meridian. It is at an elevation of 300 feet above sea level, on the east side of Culross Bay about 1,500 feet from shore. This is location 106 of MacKevett and Holloway (1977), location 169 of Cobb and Tysdal (1980), and location S-102 of Jansons and others (1984). Cobb and Tysdal (1980) summarized the relevant references under the name Thomas-Culross. This location is accurate to within 300 feet. |
Geologic descriptionThe Thomas-Culross mine is within the Contact Fault zone, a major thrust fault that juxtaposes the Valdez Group of Late Cretaceous age with the Orca Group of Tertiary age. The Contact Fault zone formed 65 million to 35 million years ago and ranges from 1 to 6 miles wide. Within this zone are numerous discrete shears. The general trend of the Contact Fault zone is northeast, but the strike of individual shears may vary widely. The country rocks at the mine consist of sheared Orca Group greenstone, which is rehealed by quartz veins that contain arsenopyrite, chalcopyrite, galena, pyrrhotite, sphalerite, and gold. Slate and graywacke outcrop about 50 feet north of the portal. The shear zone is traceable for about 900 feet and strikes N 10 E with a vertical dip (Johnson, 1914 [B 592-G, p. 235-236]). The quartz veins within the zone range from 1 to 14 inches wide and show banding; some arsenopyrite is disseminated in the surrounding wall rock (Johnson, 1914 [B 592-G, p. 235-236]). The extensive workings on the property were developed over a period of about 30 years. There are a total of 720 feet of adits and drifts, along with a 180-foot raise. A 1,350-foot-long aerial tramway connected the mine to a 10-foot Chilean mill (Jansons and others, 1984). Estimated production from this mine is 62 ounces of gold and 52 ounces of silver (Jansons and others, 1984). | |
| Geologic map unit | (-148.178057450614, 60.7365923068738) |
|---|---|
| Mineral deposit model | Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a) |
| Mineral deposit model number | 36a |
| Age of mineralization | Eocene or younger; the mineralized shear cuts Eocene greenstone of the Orca Group of Tertiary age. |
| Workings or exploration |
The extensive workings on the property were developed over a period of about 30 years. There are a total of 720 feet of adits and drifts, along with a 180 foot raise. A 1,350-foot aerial tramway connected the mine to a 10 foot Chilean Mill near the beach (Jansons and others, 1984). Estimated production from this mine is 62 ounces of gold and 52 ounces of silver (Jansons and others, 1984). The U.S. Bureau of Mines collected multiple samples from this property that assayed from trace to 14.8 ppm gold and trace to 6.5 ppm silver. (Jansons and others, 1984). |
|---|---|
| Indication of production | Yes; small |
| Reserve estimates | The U.S. Bureau of Mines estimated an indicated reserve of 8,600 tons at 5.5 ppm gold and 3.4 ppm silver (Jansons and others, 1984). |
| Production notes | Estimated production from this mine is 62 ounces of gold and 52 ounces of silver (Jansons and others, 1984). |
| MRDS Number | A010555 |
|---|---|
ReferencesSmith, S.S., 1917, The mining industry in the Territory of Alaska during the calendar year 1915: U.S. Bureau of Mines Bulletin 142, 65 p.
Smith, S.S., 1917, The mining industry in the Territory of Alaska during the calendar year 1916: U.S. Bureau of Mines Bulletin 153, 89 p.
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| Reporters | Jeff A. Huber (Anchorage) |
| Last report date | 2/11/2000 |