| Quadrangle map, 1:250,000-scale | NL |
|---|---|
| Quadrangle map, 1:63,360-scale | A-4 |
| Latitude | 64.049 |
| Longitude | -157.937 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | This site consists of two occurrences, informally called Madelyn's gossan and Nate's gossan. Madelyn's gossan is located near the summit of locally-named 'Survey Ridge,' a prominent, east-west-trending ridge about a mile west of upper Illinois Creek. For this record, the site is plotted at an elevation of 1000 feet, near the center of the N1/2 of sec. 5, T. 17 S., R. 5 E., Kateel River Meridian. The location is accurate within 2 miles. Nate's gossan is approximately 1.2 miles east-northeast of Madelyn's gossan. |
Geologic descriptionMadelyn's gossan consists of sparse, limonitic, quartzite float. Samples contain 10-20% banded limonite after pyrite. Analyses of four rock samples show only slightly anomalous values, including up to 226 ppm zinc, 2.3 ppm silver, and 30 ppb gold (Flanigan, 1998). Nate's gossan is a small outcrop (10 by 50 meters) of limonitic, brecciated quartzite. The limonite replaces banded and veined sulfides (pyrite?). Traces of malachite occur in nearby graphitic schist. Four rock samples contained up to 80 ppm copper, 308 ppm zinc, 1.0 ppm silver, and 25 ppb gold (Flanigan, 1998). | |
| Geologic map unit | (-157.939438027308, 64.0483437978293) |
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| Age of mineralization | The nearby Khotol pluton has been dated by K-Ar and Ar/Ar methods at 108-112 Ma (Flanigan, 1998). Flanigan links these occurrences to magmatic fluids from that pluton. |
| Alteration of deposit | Sulfides are oxidized to limonite, and, locally, to malachite (Flanigan, 1998). |
| Workings or exploration | These occurrences were discovered by Anaconda Minerals Company in 1980; geologic mapping and sampling followed (Flanigan, 1998). |
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| Indication of production | None |
| MRDS Number | 10307901 |
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ReferencesFlanigan, B., 1998, Genesis and mineralization of ore deposits in the Illinois Creek region, west central Alaska: University of Alaska, Fairbanks, M.Sc. thesis, 125 p., 2 plates. | |
| Reporters | C.E. Cameron (Northern Associates, Inc.) |
| Last report date | 8/7/2001 |