Infrared spectroscopy (IR) is a powerful tool to decipher the molecular groups in the minerals. This technique of detection, using atomic vibrations of molecules, that is identified through a process of absorption, makes possible the necessary mechanisms of phase analysis of minerals. In this paper, after a brief description of infrared spectroscopy, two groups of minerals will be explained by this method: Determination of the modification of the mineral kaolinite in OH spectrum (region 3700 - 3400 cm^-1) in fine to medium particle fraction <0.63 mμ in a sandstone and behavior of 2 carbonate minerals (dolomite and calcite) in the range of 2000 - 600 cm^-1. The Type of kaolinite (in fine and middle class clay of the sandstone) was determined using the different spectrum as fireclay. The shift of the absorption bands of carbonate in the range of 2000 - 600 cm^-1 is significant. This shift in the absorption spectrum shows that, where appropriate, a quantitative analysis can be achieved by calibration.