Sand is a naturally occurring granular material composed of finely divided rock and mineral particles. As the term is used by geologists, sand particles range in diameter from 0.0625 (or mm) to 2 millimeters. An individual particle in this range size is termed a sand grain. The next smaller size class in geology is silt: particles smaller than 0.0625 mm down to 0.004 mm in diameter. The next larger size class above sand is gravel, with particles ranging from 2 mm up to 64 mm (see particle size… (More on Sand)