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The 2-0.2µ and 0.2 µ clay fractions of different horizons of an Aquic Hapludalf soil , in Guilan Province, were studied by means of an electron microscope. The kaolinite clays appeared in pseudohexagonal forms in coarse clay samples while the finer clays contained “lumpy” aggregates with irregular surfaces, indicating the presence of montmorillonite or vermiculite-montmorillonite . The elongated flakes may represent illite clays , which have a lath-shaped nature . The tubular particles found in the coarse fraction suggest the presence of halloysite The irregular shape of the kaolinite clays in the surface horizon reveals more severe weathering in this zone . The discrete particles of iron oxides may also suggest that these compounds do not exist as a coating around the clay particles, but may be attached to the edges of particles . The silicatE clays , with the
exception of halloysite, have also been detected by X-ray techniques