Sandstone
Devonian Old Red Sandstone from Mitcheldean, Gloucs
A sedimentary rock composed of sand-sized grains where the grains are often mainly quartz but may also include significant amounts of rock fragments and feldspar. Sandstones composed of quartz and feldspar are termed arkoses. Smaller amounts of mineral oxides, bioclasts and clay minerals may also be present. Sandstones may have a quartz of calcite cement or a clay matrix.