Tripoli and Ganister
Tripoli, or “amorphous” silica, is mined from Devonian rocks in Alexander County. The silica is finely ground for use as a polishing agent, as a filler, in buffing compounds, and for other purposes.
Ganister, a granular material with a high silica content, also is mined in extreme southern Illinois. It is used in making products that can withstand high temperatures.