Natural sand is deposited by fluvial processes, i.e., by running or moving water. The sand size is a function of the velocity of the water - finer sands deposited by more slowly moving water. The characteristics of sand - the composition of sand particles - depend on the source, and the distance from the source. The further away the source, the more rounded, and generally more durable particles of sand are deposited. The long travel tends to break up the softer particles, so only harder, durable fraction is deposited.
The source, of course, determines the petrographic characteristics of the sand. Sands derived from the Canadian Shield source are quartz and feldspar rich, whereas those forming beaches in tropical areas are carbonate rich, containing fragments of shells.
Example
of a granite-source sand. The white and tan fragments are feldspar, and
glassy fragments quartz. The dark particles are biotite and hornblende.
