Sandstone is a sedimentary rock built of grains of sand held together by a natural cement. The most common sand in sandstone is quartz, though feldspar and rock fragments may also be present. The cement may consist of silica, calcium carbonate, iron oxide, lime, or clay. When quartz sand grains are tightly cemented with silica, they form the hard compact rock called quartzite. Sandpaper Uses of sand.
Sand is a major ingredient of mortar, plaster, concrete, and asphalt paving.
Bricks made of clay mixed with sand are harder and will bear a greater weight than bricks composed of clay only. Molds used in foundries for casting metal are made of sand with a clay binder. Sand is also used as a filter to purify water and as an abrasive. It is glued to paper to make sandpaper. Blown through a hose by compressed air or steam, sand is used as sandblast to clean the walls of brick or stone buildings, to remove paint, and to clean metal articles.