Field studies were carried out in an area of approximately 700 km2 northwest of Siirt city center, and the section consisting of gypsum interbedded claystone and siltstone of the Sulha Member of the Lice Formation was studied. Thin sections of 35 samples taken from these rocks were examined using an optical microscope. In the siltstone samples, monocrystalline and polycrystalline quartz, plagioclase and orthoclase from the feldspar group minerals and micritic limestone fragments were determined as the main components, as well as chert, clay minerals, mica minerals (biotite and muscovite), rutile, iron oxide minerals and fossil shells as minor components. In the thin sections of the gypsum samples, gypsum and halite were the main minerals. In the mineralogical compositions of 32 samples, detailed clay X-ray diffraction (XRD) diffractograms were taken and quartz, plagioclase, biotite, muscovite, calcite, gypsum, anhydrite, bassanite, thenardite, vermiculite, chlorite, kaolinite, illite minerals were determined. It has been interpreted that there is a transformation between gypsum, bassanite and anhydrite minerals, that chlorite is the decomposition product of biotite and kaolinite is the decomposition product of orthoclase. High titanium oxide ratios determined in X-ray fluorescence (XRF) and energy dispersive x-ray (EDX) analyses were associated with rutile mineral. Fibrous gypsum crystals were examined in detail in scanning electron microscope (SEM) analyses. The results of industrial tests applied to five claystone samples and chemical parameter calculations showed that they were not suitable for ceramic raw materials; however, three samples could be used as cement raw materials.