Comparison of Sandstone and Limestone | Engineersdaily ...
The usual cementing material in sandstone is calcium carbonate, iron oxides, or silica, and the hardness of sandstone varies according to the character of the cementing material; quartz sandstones cemented with quartz are the sandstones, sand is between 1/16 millimeter and 2 mm in size (silt is finer and gravel is coarser).