Clay minerals play an important role in the gravitational stability of man-made rock piles by affecting geotechnical and hydrological characteristics of the material. FT-IR technique is used to distinguish between different types of minerals and to derive information concerning their structure, composition and structural changes upon chemical modification. The selections of the sample technique used depend on the purpose of the study and on the physical state of the sample. KBr pressed disk technique was found to be very useful for a routine characterization of both di and trioctahedral clay minerals. We have studied the mineralogical characteristics of clay deposits from Keeliruppu, Panruti, Cuddalore District, Tamilnadu, India. To determine their composition and possible use in local industry. The studied deposits are chemically homogenous, except for the samples richer in kaolinite and sand fraction. The clay samples were subjected to FT-IR analysis in the region of 4000 - 400 cm-1, which can be used to characterize the different minerals. The mineralogical composition of the clays has demonstrated that, taken as a whole, they possess characteristic satisfactory for brick production.