Feldspar-Bearing Sands
Feldspar is the name applied to a group of minerals that are mainly silicates of potassium, sodium, and calcium. Various kinds of feldspar are used industrially in making glass, enamels, pottery, and other products. All the feldspar now used in Illinois is shipped into the state. The discovery by the Illinois Survey that some Illinois sands contain considerable feldspar led Survey geologists and chemists to find where deposits highest in feldspar occur, what kinds of feldspar they contain, and whether it could be separated from the sand in which it occurs. Beach sands, river sands, dune sands, and sands from other kinds of deposits were studied.
It was found that many sands contain more than 15 percent feldspar and some as much as 25 percent. Means of separating the feldspar from the sand are believed to exist, but problems relating to the purity of the separated spar remain to be solved.