Limestone is a sedimentary rock composed mostly of the mineral calcite and comprising about 15% of the Earth’s sedimentary crust. It is a basic building block of the construction industry dimension stone and the chief materials from which aggregate, cement, lime, and building stone are made. 71% of all crushed stone produced in the U.S. is either limestone or dolomite. As a source for lime, it is used to make paper, plastics, glass, paint, steel, cement, carpets, used in water treatment and purification plants, in the processing of various foods and household items including medicines .
The largest use of lime is in steel manufacturing where lime is used as a flux to remove impurities such as phosphorus and sulfur. Lime is used in power plant smokestacks to remove sulfur from the emissions. Lime is also used in mining, paper and paper pulp production, water treatment and purification, and in wastewater treatment. It is used in road construction and traditional building construction.
Limestone is defined by these two criteria: it is a sedimentary rock 1 and it is composed of calcium carbonate 2 . There are other rocks that are composed of calcium carbonate. Carbonatite is a rare type of igneous rock and marble is a common metamorphic rock. Both are chemically composed of calcium carbonate, but they are not limestones because they are not sedimentary rocks.