Sandstone
any stone which is an agglutination of grains of sand, whether calcareous, siliceous, or of any other mineral nature. Siliceous sandstones are the most common. They vary in compactness from scarcely cemented sand to a hardness approaching that of quartz rock.
When very fine in grain, they are called freestones; when coarse and composed of angular or subangular grains of sand, they become grits; when pebbly, pudding stones. Sandstones occur in nearly every geological formation from the Cambrian to the Tertiary. Many furnish building and paving stones.