Silica sand is used in making glass, for sand blasting, as grinding
sand, as molding sand for casting steel, and in the fracture treatment
of oil wells to increase oil production. Some of the sand is finely
pulverized into a powder that is used as a filler, a fine abrasive, as a
ceramic material, and for many other purposes.
This special sand, composed of grains of the mineral quartz (silica),
comes from a sandstone of Ordovician age that is mined in LaSalle and
Ogle Counties.