Sandstone is a sedimentary rock formed from a variety of different minerals and rock grains. The stone gains its name due to its formation from a base of sand that compacts and cements into large rock formations. Because small grains of sand can be made up of any type of rock or mineral, there is incredible variety in sandstones. Sandstone is usually made up of quartz and feldspar, however, simply because they are the most common minerals on the surface of the earth.
Although sandstone is made up of very common minerals, this does not in any way decrease its value or visual appeal. The colour and appearance of each different type largely depends on its original environment, with many sandstones being singularly distinctive to their locale. The stone is often found in dry, inland seas and in desert areas, where there is, or has been, a significant amount of erosion.
Sandstone is also categorised depending on the environment it was quarried from, because factors such as grain size, sedimentary structure and composition are greatly effected by the original environment and age of the sandstone. Further classifications are made depending on mineralogy and texture of the stone.
Geologists have not yet agreed on a singular way to classify sandstone, but there are many different methods which follow a general pattern. Using these classification methods it is possible to determine some types, such as: quartz arenites which contain more than 90% siliceous grains, lithic arenites which contain a high proportion of unstable lithic fragments, feldspathic wackes which contain a matrix greater than 15%, and many more.