Mineralogical evaluation of lateritic soil of selected zones in Udupi district, Karnataka, India

Lateritic soil is one of the main soil types in the tropical countries like India for basic construction works. Since lateritic soils are the main underlying soil structure in coastal Karnataka, its detailed study of mineralogical properties is of utmost importance. The study area chosen is Udupi district and samples were procured from coastal plains and hinterland regions. The samples taken from each places (three layers-top, middle and bottom at around 2.5-3 m depth) were collected in zip locked polythene bags and were oven dried at 1050 Celsius for 24 hours and then passed through 75 µm IS sieve size. For clear images of the soil structure and for identification of elements, samples were coated with gold sputtering. These samples were tested by Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectroscopy (EDAX/EDS) and analyzed. SEM results show various minerals present in the samples. EDAX results show the percentage of each element (like C, O, Si, K, Cu, Ti, Mg etc) present in the sample. Therefore it can be concluded that laterites change their composition from iron to aluminium resulting in bauxite ore as one moves towards north in the coastal belt of Karnataka.