<em>Answer:</em>
<em>Limestone is a type of carbonate sedimentary rock. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate. A closely related rock is dolomite, which contains a high percentage of the mineral dolomite, CaMg(CO₃)₂.</em>
<em>Limestone has numerous uses: as a building material, an essential component of concrete (Portland cement), as aggregate for the base of roads, as white pigment or filler in products such as toothpaste or paints, as a chemical feed stock for the production of lime, as a soil conditioner, and as a popular decorative .</em>
<em>Limestone is formed in two ways. It can be formed with the help of living organisms and by evaporation. Ocean-dwelling organisms such as oysters, clams, mussels and coral use calcium carbonate (CaCO3) found in seawater to create their shells and bones.</em>
<em>LIMESTONE MEANING:</em>
<em>a rock that is formed chiefly by accumulation of organic remains (such as shells or coral), consists mainly of calcium carbonate, is extensively used in building, and yields lime when burned.</em>
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