X-ray Studies on the Distribution and Characterization of Layer Silicates in Some Alluvial Soils

The clay-mineral composition of soil from four profiles representing the Hissar, Suniarheri, Tohana and Bhanra soil series developed on alluvium has been examined using the x-ray diffraction and microscopic techniques Quartz and feldspars were the dominant minerals present in the sand fractions; muscovite, biotite and chlorite in association with other accessory minerals were also indicated. Semiquantitative estimates of minerals in the silt fractions suggested the dominance of illite followed by mixed-layer minerals, chlorite, and vermiculite. A similar distribution pattern was also observed in the clay fraction which contained, in addition, smectite and chloritized-smectite. The illite present in the soils was found to consist of both the dioctahedral and trioctahedral varieties, and the latter appears to have undergone transformation to smectite-like minerals through intermediate stages of (10–14 A) inters-tratification.