Sand

Definition

Sand is a loose granular substance resulting from the erosion of rocks and minerals. The word has two meanings: sand is defined as a size class if used in terms of a single grain, or as a textural class when used in terms of an aggregate of grains. As a general rule, sand feels gritty when rubbed between the fingers. Silt, by comparison, feels like flour.

The two most widely used size classification schemes to define sand are the Unified Soil Classification System (USCS) and the Krumbein phi scale. The Unified Soil Classification System defines sand as particles with a diameter between 0.074 and 4.75 mm. The Krumbein phi scale defines sand as particles 1/16th mm to 2 mm, or 0.0625 mm to 2 mm. There are other less common or older classification systems as well.

Sand is found in rivers, beaches, dunes, and shallow shelf seas. The most important commercial sources of sand have been glacial deposits, river channels, and river flood plains. Whereas some countries routinely mine...