The geology and mineralogy of the Sungurlu bentonite occurrences have been investigated. In the Sungurlu region, bentonite deposits containing Oligocene–Miocene age sedimentary rocks are composed of alternations of gypsum, mudstone, tuff, and minor amount of fine-grained sandstone. The bentonites have sedimentary origin. Na-montmorillonite was determined by the X-ray powder diffraction analyses of clay size. Detrital quartz, feldspar, gypsum, calcite, metamorphic, and volcanic rock fragments are common impurities.