Sandstone is actually a rock, not a stone. Sandstone can be defined as a physical sedimentary rock containing a high percentage of quartz grains. Sandstone is the natural cement of sand and can be of different colors. In the field, areas of sandstone density are defined by different colors. Sandstone areas with sandstone can act as oil reservoirs as they allow water and different liquids to penetrate and act as oil reservoirs. The structures that provide the formation of sandstone and hold the sand grains together are calcite, silica and clay.