Limestone and sandstone, are common types of sedimentary rock, not very compact, and with smaller hardness that marbles and granites. The limestone is usually composed of calcite (calcium carbonate), of animal origin in many cases.   The sandstone has the same chemical constitution of the sand, binded by silica or iron oxide, determining at the same time the rock color. Both rocks are used in construction industry, and the sandstone as abrasive in different industries.