Size Terms
Grains between 1/16mm and 1/256mm are called Silt
Grains less than 1/256 mm are called Clay
Sand, Silt and Clay are Size terms. A sandstone is a sedimentary rock made up of Sand sized grains.
Sandstones account for about 10% of the Earthís sedimentary rocks
Clay and Silt sized grains are dominated by clay minerals