The Zonguldak Coal Basin is located in Northwest Turkey, coast of Black Sea. During field work, 32 fine-grained rock samples (mainly marl and a few fine-grained sandstone) were collected from the coal bearing formations (Alacaagzi formation of Namurian age) and overlying Aptian-Cenomanian (Cretaceous) aged formations such as Tasmaca and Sapca Formations. In this study, represent samples from different formations were used for identification of mineralogy using XRD and SEM-EDX. Selected 12 samples were also analyzed in detail to understand pore size distribution and its relation to mineralogical composition. The mineralogical compositions of the samples on powder samples with XRD and polished briquettes with SEM-EDX show that the samples contain clay minerals (mainly illite and chlorite and less kaolinite), quartz, calcite and feldspar. The organic carbon contents of the 12 samples studied are ranging from 0.74 to 1.21 %, indicating relatively low carbon contents.