Stockton and Stanley Hill clay deposits, Kootenai County, Idaho
The Stockton and Stanley Hill deposits, Kootenai County, Idaho, are about 25 to 30 miles east of Spokane, Wash. During World War II, the areas were studied by the U. S. Geological Survey in cooperation with the U. S. Bureau of Mines. The Bureau of Mines hand-augered 162 holes and made chemical analyses of the samples for available alumina, and available ferric oxide, and measured the ignition loss. The deposit contains two types of clay: granite residual clay derived from the weathering of Cretaceous granite gneiss in place; and transported clays of the Latah formation derived from the weathered. debris of the granodiorite and older rocks. The Stockton deposits average more than 20 percent available alumina and less than 10 percent available ferric oxide. The deposits, therefore, could serve as a small source of low-grade high alumina clay. Clays containing more than 15 percent available alumina and less than 5 percent available ferric oxide would be suitable for many ceramic products and some may meet the requirements for high-heat or super-heat duties. Therefore, the Stockton and Stanley Hill clay deposits contain ceramic-grade clays.