In southern Illinois deposits of sand laid down in an arm of the ocean
that once extended northward into Illinois from the Gulf of Mexico are
found in Alexander, Union, Pulaski, Pope, and Massac Counties. The
deposits are commonly a light color—white, cream, yellow, or gray.
The grains of the sand are almost all quartz and generally are angular.
Some of the sands are of almost powder-like fineness, others are fine or
medium grained. Many of the sands contain flakes of white mica, a
glistening, silvery-looking mineral often mistaken for silver or
platinum. Unlike these metals, however, mica is comparatively light in
weight and is not metallic. Also present in some sands are small flakes
of the mineral graphite.
The southern Illinois sands have not been widely used, but some of them
have been employed in making concrete. They also may have possibilities
for molding and core sand.
As a result of work by Survey geologists, the location and properties of
many of the southern Illinois sand deposits are known.