Middle Tennessee Mining District, DeKalb County, Tennessee, USAi

Regional Level Types
Middle Tennessee Mining District	Mining District
DeKalb County	County
Tennessee	State
USA	Country

A baryte mining district spread across several Tennessee Counties (DeKalb, Smith, Wilson, Rutherford, Cannon, Williamson, Trousdale, and Putnam Counties). NOTE: This district is spread across so many counties that the detailed geological description is limited to this file for the district as a whole. Individual mines are listed under the district in their respective counties.

Veins containing barite are widely distributed in the limestones of Ordovician age that crop out on a structural arch in middle Tennessee. The arch trends NE and is about 100 miles long and 50 miles wide. Most of the veins are in the Carters limestone, but some veins also are in the overlying and underlying limy rocks. The limestones are locally sandy, shaly, or dolomitic. Most of the deposits are within 20 miles of the junction of DeKalb, Smith, and Wilson Counties, but others are in Rutherford, Cannon, Williamson, Trousdale, and Putnam Counties.

The veins occur along northeast-trending faults that generally are not persistent along strike and have a throw of not more than a few tens of feet. The faults are nearly vertical. A few have been traced about 3 miles, but most are much shorter. The displacement is mostly horizontal, or nearly so. The faults are marked by polished walls, zones of breccia 5 to 6 feet wide, and greatly fractured zones as much as 20 feet wide. The mineralized parts of the faults are generally less tna 3 feet wide. Faults trending NW are not mineralized and are considered to postdate the mineralized northeast-trending faults.

The vein minerals generally cement fault-breccia and fractured zones, although some filling of fissures and replacement of limestone fragments has occurred. The veins pinch and swell within short distances both laterally and vertically. Veins 2 feet (60 cm) wide pinch to 2 inches (5 cm) with about 12 feet (3.5 meters), and then widen again within the same distance. The contacts of the veins with the walls are sharp. Replacement of the limestone has been confined to fragments in the fault zones. Deep alteration of the wall rocks apparently did not occur, and no lateral extensions of the veins as blanket veins or bedded replacement deposits have been reported.

Banding parallel to the walls of the veins and concentric bands around fragments in the breccia are common. These bands, as many as a dozen over a distance of a few inches, are locally asymmetrical.

The upper parts of the veins are considerably weathered. Calcite and limestone fragments have been leached, leaving a porous mass of barite and fluorite containing molds of the dissolved fragments. Calamine and limonite occur as alteration products. The ultimate result of weathering is soil with lumps of white porous barite and limonite.

Other Regions, Features and Areas containing this locality

References