| Quadrangle map, 1:250,000-scale | ID |
|---|---|
| Quadrangle map, 1:63,360-scale | D-2 |
| Latitude | 62.98249 |
| Longitude | -156.99724 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | This prospect at an elevation of about 1,400 feet on an unnamed tributary of Tolstoi Creek. It is about 1.0 mile north of hill 2008 and about 0.4 mile southwest of the northeast corner of section 2, T. 33 N., R. 41 W., of the Seward Meridian. The location is accurate. |
Geologic descriptionThe Tolstoi Creek prospect is a black-sand-rich gold placer that contains visible gold, abundant magnetite, ilmenite, less abundant ilmenorutile, a Nb-Ta mineral, cinnabar, tourmaline (variety dravite), and a trace of chalcopyrite (Bundtzen, Cox and Veach, 1987). The creek is about 30 feet wide and is incised in glacial moraine of late Pleistocene age. The alluvium is poorly sorted; most of the gold and heavy minerals occur in sand and gravel that is interstitial to erratic boulders that originated in the Beaver Mountains (Bundtzen and Laird, 1980). The placer gold is mostly fine-grained with occasional grains to 5 mm across. Six pans collected at intervals across the creek contained from 1 to 5 grains of gold per pan (Bundtzen, Cox and Veach, 1987). The average fineness of the placer gold as determined by fire assay is 891. One placer concentrate contained 214 parts per million (ppm) niobium 14 ppm tantalum, 8.1 ppm gold, and 1.0 ppm silver (Bundtzen, Cox, and Veach, 1987). | |
| Geologic map unit | (-156.999599341598, 62.9818379570869) |
|---|---|
| Mineral deposit model | Placer Au deposit (Cox and Singer, 1986; model 39a). |
| Mineral deposit model number | 39a |
| Age of mineralization | The prospect is in reworked, glacial moraine of Late Pleistocene (Wisconsin?) age and the placer is either late Pleistocene or Holocene in age (Bundtzen, 1980 [GR 63]). |
| Alteration of deposit | None. |
| Workings or exploration | Placer occurrences in this area were prospected during the early part of the 20th century (Mertie, 1936). The placer was sampled by the Alaska Division of Geological and Geophysical Surveys in the 1980s (Bundtzen, Cox, and Veach, 1987). |
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| Indication of production | None |
| Production notes | No known production. |
ReferencesBundtzen, T.K., Cox, B.C., and Veach, N.C., 1987, Heavy mineral provenance studies in the Iditarod and Innoko districts, western Alaska: Process Mineralogy VII, The Metallurgical Society, p. 221-246.
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| Reporters | T.K. Bundtzen (Pacific Rim Geological Consulting, Inc.), M.L. Miller (U.S. Geological Survey); and C.C. Hawley (Hawley Resource Group) |
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| Last report date | 5/11/2003 |