Types of Rock Found in Southeastern Tennessee

Southeastern Tennessee includes the counties of Franklin, Grundy, Marion, Hamilton, Bledsoe, Sequatchie, Rhea, Meigs, McMinn, Bradley and Polk. A lot of information about the geological resources of southeastern Tennessee is collected and disseminated by the Tennessee Division of Geology, which was once the Tennessee Geological Survey. Tennessee was one of the first states to establish a geologic service and research organization.

Gemstones

• Agate is thought to be plentiful in some areas of Tennessee, but it's difficult to get to.

  Tennessee is known for its Tennessee River pearls and agates. Agates are found in the southeastern counties of Franklin and Grundy, and are thought to be all over the side of the Cumberland Plateau. Most of the sites are on private property and require getting the permission of the landowner, but it is almost impossible to get the right to collect, according to Tennessee silversmith Will Smith. The Tennessee River Pearl is farmed today. It had been traded by Native Americans in the region for hundreds of years.

Sedimentary Rock

• Limestone blocks are often used as grave markers.

  Sedimentary rock is found throughout Tennessee and is plentiful in the southeast region of the state. Limestone, composed of calcium carbonate, makes up 10 percent of all sedimentary rock. Types of limestone found in the region include Carters, Lebanon, Ridley, Pierce and Murfreesboro limestone. This white, or almost white rock, is popular in architecture. Landmarks and monuments are often made from limestone because of how well the rock stands up to the elements. It is also easy to make blocks from limestone and to carve designs into it. Skyscrapers are sometimes sheeted with limestone.

Hydrocarbon Rocks

• Drilling often takes place in shale formations.

  There are several types of rocks in southeastern Tennessee that indicate the presence of oil. One of the best known among drillers in Tennessee is Chattanooga shale, a natural gas shale rich in hydrocarbons. Atlas Energy ATN, CNX Gas Company CXG and GeoMet GMET are pursuing drilling rights in this shale deposit, according to Oil & Natural Gas News, and studies are underway by oil companies to identify hydrocarbon occurrences. The Chattanooga shale field is an extension of the Macellus shale field (Appalachian Basin Devonian shale) and the Black Warrior Basin in Alabama.

Mineral Rocks

• Southeast Tennessee has mineral rocks, such as feldspar, bentonite and dolomite. Bentonite is common in Hamilton County at the Chickamauga dam. Mineral rocks, such as k-bentonite (potassium-bentonite), are named according to what they contain --- potassium, calcium, sodium or aluminum --- calcium is the secondary mineral in the bentonite at the Chickamauga dam, according to Christopher Howard of the University of Tennessee. Bentonite is often formed from volcanic ash.