Limestone: The Calcium Carbonate Chemical Sedimentary Rock
" Limestone " means any rock formed mostly of calcium carbonate (CaCO 3 ), but to geologists, limestone is only one of several types of "carbonate rocks.". These rocks are composed of more than 50% carbonate minerals, generally the minerals calcite (pure CaCO 3) or dolomite (calciummagnesium carbonate, CaMg[CO 3] 2) or both.