Sedimentary rocks formed from the consolidation of sand, with sand-sized grains (0.06252 mm/0.00250.08 in) in a matrix or cement. Their principal component is quartz. Sandstones are commonly permeable and porous, and may form freshwater aquifers. They are mainly used as building materials.
Sandstones are classified according to the matrix or cement material (whether derived from clay or silt).