Characterisation of Clay Minerals in Major Soil Groups of West Bengal and South India

Black, alluvial, red and latosol soils from West Bengal and South India were examined for clay mineral identification. The values obtained for silica/sesquioxides, cation exchange capacity, and the pattern of potentiometric titration curves indicate that the black soil was dominated by montmorillonitic clay minerals, alluvial and red soils had variable admixture of montmorillonite, illite and kaolinite. While kaolinite tended to dominate in alluvial soil, there was comparatively high proportion of illite in red soil clays; kaolinite dominated in clays of latosols having possible admixture with expanding lattice clay minerals in minor proportions. An attempt has been made to corroborate the results of clay mineral identifications with primary minerals examined and the rock association to study the mode of formation of clay minerals under varying geological complexes