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Reconnaissance of Tatonduk River Red Beds.
Hematitic red beds of Cambrian to preCambrian age are exposed in the Tatonduk River Valley 17 miles north of Eagle, Alaska, the nearest habitation. Reconnaissance was conducted briefly by Bureau of Mines engineers in June 1962 and September 1963. Access was gained by small river boat traveling 28 miles down the Yukon River from Eagle, thence 8 miles up the Tatonduk. The red beds are dominantly hematitic tuffaceous shales and conglomerates having an estimated thickness of 1,800 feet and an exposure area of more than 6 square miles. Nearly 800 feet of stratigraphic thickness was chip samples in a series of discontinuous sections that assayed 4.73 to 24.7 percent soluble iron. Assays of 20.10 percent soluble iron for a 133-foot thickness, and 21.85 percent soluble iron for a 200-foot thickness are the highest obtained for significant thicknesses. A 3/4-inch thick slaty bed assayed 33.4 percent soluble iron, the maximum assay obtained. Analyses of five bulk samples show the iron occurs as extremely fine, earthy hematite with only a trace of magnetic material and is not amenable to simple magnetic or gravity concentration.
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division