Soil is made up of mineral particles which vary in shape, size and chemical composition. Sand particles are quite large because they break down slowly. Other minerals break down more quickly into clay particles. These are extremely small – many thousands of times smaller than coarse sand – and they have an important effect on the physical and chemical properties of the soil. The size of the particles – coarse sand, fine sand, silt and clay – and the proportions in which they occur determine soil texture.