| Main commodities | As; Cu; Zn |
|---|---|
| Ore minerals | arsenopyrite; chalcopyrite; malachite; pyrite |
| Quadrangle map, 1:250,000-scale | CH |
|---|---|
| Quadrangle map, 1:63,360-scale | C-4 |
| Latitude | 67.666 |
| Longitude | -148.9968 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | This occurrence is about 1.5 miles above the mouth of Willow Creek. The creek is a 5-mile-long, headwater tributary to Robert Creek. The occurrence is about 0.4 mile southwest of the center of section 19, T. 33 N., R. 6 W. |
Geologic descriptionKurtak and others (2002) examined the canyon of Willow Creek, about 1.5 miles above its mouth. The rocks in the area are Devonian chlorite-muscovite schist in thrust contact with quartz-muscovite-chlorite schist. Two iron-stained exposures of sericite schist up to 25 feet wide contain pyrite bands that average 0.8 foot thick and parallel the schistosity. The bands also contain arsenopyrite and trace chalcopyrite and malachite. A 7-foot chip sample across pyrite bands up to 0.5 foot thick contained 1,679 parts per million (ppm) copper and 367 ppm zinc. None of the samples contained precious metals. | |
| Geologic map unit | (-148.999552584869, 67.6656033545324) |
|---|---|
| Mineral deposit model | Schist with bands of pyrite and minor copper and zinc. |
| Age of mineralization | Devonian or younger based on the age of the host rock. |
| Alteration of deposit | Iron staining of pyritiferous schist. |
| Workings or exploration | Only limited sampling by the U.S. Bureau of Land Management. |
|---|---|
| Indication of production | None |
| Reserve estimates | None. |
| Production notes | None. |
ReferencesKurtak, J.M., Klieforth, R.F., Clark, J.M., and Maclean, E.A., 2002, Mineral investigations in the Koyukuk mining district, northern Alaska, 2 vols.: Bureau of Land Management, Alaska Technical Report 50, 845 p. | |
| Reporters | D.J. Grybeck (Contractor, U.S. Geological Survey) |
|---|---|
| Last report date | 4/18/2010 |