The Stanford clay deposit, Latah County, Idaho, is about 4 miles northwest of Deary, Idaho. During World War II, the area was studied by the U. S. Geological Survey in cooperation with the U. S. Bureau of Mines. The Bureau of Mines hand-augered 10 holes and made chemical analyses on the samples for available alumina and available ferric oxide, and also measured the ignition loss.
The deposit contains three types of clay: granitic residual clay derived from the weathering of Cretaceous granodiorite in place; basaltic residual clay derived from the weathering of Tertiary Columbia River basalts in place; and transported clays of the Latah formation derived from the weathered debris of the granodiorite and older rocks. Only the transported clays are considered as a potential source of available alumina and ceramic-grade clay in the Stanford deposit.
The Stanford deposit averages 24.8 percent available alumina and 2 percent available ferric oxide.
Transported 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 of high-heat or super-heat duties. Therefore, the clays are usable for ceramic structural ware such as bricks, terra cotta, and drain tile.
