Clay and Clay Products
Illinois commercial clays are found in glacial, Cretaceous, Tertiary, and Pennsylvanian deposits. Pennsylvanian shales also are sources of clays. Glacial clays, which occur as loess (wind-blown materials), alluvial (water-deposited) sediments, and glacial till, are widespread in the state. Cretaceous and Tertiary clays, at the extreme southern tip of the state, are valuable for the manufacture of heat-resistant bricks and coatings and for floor-sweeping compounds.
Pennsylvanian clays and shales are the most important source of clay for manufacturing such products as pottery, stoneware, drain tile, sewer pipe, flue tile, building tile, brick, and special heat-resistant fire-brick.