Figure 10—Limestone and dolomite are quarried at many places, but fluorspar, zinc, and lead are produced in restricted mineralized areas.
KEY Quarry, Limestone or Dolomite Cement or Lime Fluorspar Zinc and Lead
Limestone and shale or clay are burned together in kilns to produce portland cement. Portland cement is manufactured from a Pennsylvanian limestone in LaSalle County and from an Ordovician limestone in Lee County.
Limestone or dolomite also is burned in kilns to make lime. Mississippian limestone is used in Adams County and Silurian dolomite is used in Cook County for lime making.
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.
Sand and Gravel
Deposits of sand and gravel, found in many parts of Illinois, provide large quantities of material for concrete, railroad ballast, road gravel, building sand, molding sand, and other uses. Glacial deposits are the principal sources of sand and gravel, but in extreme southern Illinois where there is no glacial drift the main source of supply is Tertiary gravel and Devonian chert gravel.