In the course of the investigation of the Ef'e oil shale field, the inorganic chemistry of 33 composite samples from 10 boreholes was studied. Detailed analyses for organic matter content, P2O5 and U also were carried out. According to the results of these analyses, X-ray analyses and the examination of petrographic thin sections, the minerals which constitute the oil shale are: oaloite, organic matter (kerogen), kaolinite, montmorillonite, apatite, gypsun, dolomite, pyrite, and quartz.