Sand·stone n. A rock made of sand more or less firmly united. Common or siliceous sandstone consists mainly of quartz sand.
Note: ☞ Different names are applied to the various kinds of sandstone according to their composition; as, granitic, argillaceous, micaceous, etc.
Flexible sandstone Min., the finer-grained variety of itacolumite, which on account of the scales of mica in the lamination is quite flexible.
Red sandstone, a name given to two extensive series of British rocks in which red sandstones predominate, one below, and the other above, the coal measures. These were formerly known as the Old and the New Red Sandstone respectively, and the former name is still retained for the group preceding the Coal and referred to the Devonian age, but the term New Red Sandstone is now little used, some of the strata being regarded as Permian and the remained as Triassic. See the Chart of Geology.