The increasing global demand for clean energy has made it imperative to explore and exploit unconventional oil and gas resources. Twenty-five percent of the sedimentary rocks in Peninsular Malaysia are Paleozoic shales. Nevertheless, no work has been carried out on shales in the Kroh Formation as regards their mineralogical composition and the effect of minerals in the hydraulic fracturing. Representative samples of black shales from the Kroh Formation were analyzed using X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FE-SEM) with energy dispersive X-ray (EDX). The mineralogical composition of the shales has an important effect on the competency of rocks, for drilling and for hydrocarbon production. The FESEM results showed that the shale samples mainly comprised kaolinite which appears as booklets and quartz as round grain with small oval depressions of vary grain sizes. The elemental compositions of the shale samples determined by EDX confirm the minerals identified by FESEM. XRD and FESEM results both identified the minerals as illite, chlorite, pyrite, and a minor amount of dolomite, feldspar, and calcite. Knowing the clay minerals composition of the shale can be useful in planning for drilling and hydraulic fracturing. © 2020 Slovnaft VURUP a.s.