Cathodoluminescent growth zones were observed in gangue dolomite associated with sphalerite mineralization in the Mascot-Jefferson City district. A total of six major zones were recognized which luminesce from very bright to very dark red. A nearly perfect microstratigraphic correlation of the gangue dolomite Cathodoluminescent zones throughout the district was observed. A single period of sphalerite mineralization occurred during the development of three consecutive zones throughout the district. Three other districts were studied and all exhibited, to some degree, cathodoluminescent zonations. The cathodoluminescent microstratigraphy reveals that both the sphalerite and gangue dolomite were time correlative through the Mascot-Jefferson City and possibly the Copper Ridge districts.Preliminary studies suggest that Cathodoluminescent petrography has possible exploration applications in East Tennessee and other Mississippi Valley-type deposits. It may be possible to differentiate between brecciated and dolomitized areas adjacent to an orebody and similar breccias which are not mineralized.