Identification of 14Å and 7Å Clay Minerals in Punjab Soils

Detailed study of 7Å and 14Å reflections from over 50 clay samples representing 30 soil profiles from Punjab (India), indicate that all soils which hitherto have been reported to contain chlorite as a second dominant mineral (illite being the first), do not show the presence of such a mineral, but, on the other hand, contain intergrade minerals (chloritised vermicuiite and chloritised montmorillonite) which resisted collapse andjor expansion to clays without sodium citrate treatment (pH 7.3). The degree of interlayering seems to have direct correlation with the amount of alumina extracted. It has been realised that for the precise appraisal of 7Å and 14Å peaks, the use of warm HCl and sodium citrate treatments is imperative in Punjab soils.