Illinois' aggregate resources occur in a wide variety of geological settings, from limestone and dolomite bedrock units of differing age to sand-and-gravel deposits formed in diverse river, beach, and glacial settings. The aggregate program:
- inventories aggregate resources as part of the state's geological mapping program
- provides service to Illinois' aggregate producers and the public using the latest geological research and historical information
- characterizes and maps the availability and distribution of limestone and dolomite resources suitable for pH control in agriculture and for toxic emission control in coal-burning power plants
- investigates the feasibility of underground mining and the secondary use of mined-out space
- maintains a database of existing and abandoned pits and quarries
- provides mineralogical and geochemical information
- assists producers in better utilization of existing resources and locating new sources
- maintains a repository of data for characterization of Illinois aggregate resources for present and future exploration
- compiles information about Illinois mineral production and value and assists industry and the public in estimating reserves and value.
The aggregate program inventories these resources. Construction aggregates have low unit values per ton, but large tonnages of the material are needed for most construction purposes. To be economically viable aggregate resources need to be available locally because the cost of aggregate goes up significantly as the distance the material is transport increases Industrial Minerals in Illinois: A Key to Growth (456K PDF file). Not all aggregates have the suitable quality to meet engineering specifications for use in construction or other purposes because a small amount of impurities can significantly alter aggregate quality. Consequently, aggregates must pass the Illinois Department of
Transportation's stringent tests before they may be used to build state roads.