ABSTRACT
SOLID MINERAL FRACTION The solid mineral fraction alone constitutes 93 to 95% of the total soil weight. It is composed of particles varying in size, depending on the degree of fragmentation of the original parent rock. The particles can be classified according to their volume as pebbles, stones, gravel, coarse sand, fine sand and silt (Table 1.1). Alteration and transformation of these basic mineral elements give rise to another category of particles, still finer than silt (less than 2 \JLm), namely clays. The granulometric composition (i.e., the relative proportions of sand, silt and clay, estimated after the breakdown of aggregates and dispersal of clay) characterises the soil texture. Some of the physical properties of soil depend upon its texture. For instance, sand or silty sand is more permeable to water and easier to work than a soil of clayey silt or clayey texture.
