The Chattanooga Shale was deposited over much of present Tennessee when Devonian seas transgressed, leaving a thick deposit of organic rich black mud. The Chattanooga Shale ranges in thickness from less than 35 feet in central Tennessee to more than 720 feet in the eastern portion of the state. Although much thinner, the central Tennessee section of the shale appears much richer in extractable organic material, averaging 13% carbon (approximately 9.3 gallons per ton by Fischer assay) with a maximum of 20% carbon (15 gallons per ton). In central Tennessee, the Chattanooga Shale has two members, the Dowelltown and the Gassaway and is underlain by the Leipers Limestone and overlain by the Ft. Payne Chert and Maury Formation, a phosphatic claystone. Detailed mineralogy from a corehole taken in DeKalb County is presented. The abundance of kaolinite (5 to 29% of total clay fraction) differs significantly from data of other investigators, possibly suggesting a proximity to an ancient shoreline. Additionally, the samples from this corehole were higher in quartz and feldspars, and lower in overall clay mineral percentages than samples of the Chattanooga Shale reported in other areas.