Limestone is Missouri's most abundant commercial mineral. It was created 320-500 million years ago by the deposition of calcium and magnesium on ocean floors. Many limestone formations in the state contain fossils of animals that lived in the ocean, providing evidence of the interesting land-sea changes which this part of the country has undergone in the geologic past.
The Missouri Limestone Producers Association (MLPA) was organized in 1944 to promote and protect the interest of crushed stone operators located or doing business in the state. Limestone's unique physical and chemical properties allow it to have many uses. Hundreds of beautiful, historic structures in Missouri were built with it, including Daniel Boone's home, the Old St. Louis Cathedral near the Arch, and even the State Capitol Building! It has extensive use as one of the raw materials in Portland Cement. Specialty uses include the manufacturing of pharmaceuticals, toothpaste, paint, paper, caulking and glass. Common antacids are virtually 100% finely-ground limestone. Farmers use limestone to neutralize acidity in their soils. Counties use crushed limestone to provide an all-weather driving surface on unpaved roads. However, it is most commonly used as construction aggregate.