Sandstone is a type of rock made from sediment — a sedimentary rock. The sediment particles are clasts, or pieces, of minerals and fragments of rock, thus sandstone is a clastic sedimentary rock. It is composed mostly of sand particles, which are of medium size; therefore, sandstone is a medium- grained clastic sedimentary rock. More precisely, sand is between 1/16 millimeter and 2 mm in size (silt is finer and gravel is coarser). Mature continental sediment consists of a handful of surface minerals, and sandstone, therefore, is usually almost all quartz. Other minerals—clays, hematite, ilmenite, feldspar, amphibole, and mica— and small rock fragments (lithics) as well as organic carbon (bitumen) add color and character to the clastic fraction or the matrix.
Enquiry