Welcome once again to Theme Thursday. This weeks theme is mineral. Not surprising considering it follows after animal and vegetable. I picked the mineral calcite which is the main ingredient in limestone. Limestone is my home state of Missouri's most abundant commercial mineral. It was created 320-500 million years ago by the deposition of calcium and magnesium on ocean floors. Almost all 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.
I live in a small country town. The nearest freeway is a ten-mile drive along a narrow two-lane road. The road travels through areas cut into limestone bluffs. The cuts give you a feeling of driving through a natural gorge in an ever changing array of browns, reds and oranges. For months now the highway department has been working to expand those limestone canyons to create a new five-lane highway. While slowing our drive to the freeway, the roadwork has allowed us to watch as new cliffs of limestone are exposed to the sunlight after millions of years in darkness. Huge amounts of Missouri limestone are being removed during this expansion to find its way into other uses.
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! Limestone is mined in 92 of Missouri's 114 counties, and the industry employs more than 2,500 people with a combined payroll of more than $70 million. More than 75 million tons of crushed limestone products are produced in Missouri each year -- roughly 10 tons for each resident. Today, 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.
In our area there are many caves that have been left behind in the limestone bluffs from the mining of limestone. One of them recently made the world news when its owners offered it for sale on ebay. This particular 15,000 sq. ft. cave in Festus, Mo, was formerly used as a roller-rink and concert venue that entertained the MC5, Ike and Tina Turner and Ted Nugent. It has been converted into a three bedroom home. Check it out here
To see more of the posts on minerals or to join the fun visit Theme Thursday