what kind of rock is limestone

Limestone is a type of sedimentary rock composed mainly of calcium carbonate (CaCO3), primarily in the form of the minerals calcite and aragonite. It often forms from the accumulation of marine animal shells, coral, and other biological debris, deposited and compressed over millions of years, mainly in shallow marine environments. Limestone commonly contains fossils and can vary in color from white to gray, beige, or even darker shades depending on impurities. It is relatively soft, reacts with acids by fizzing, and serves many uses including construction, cement production, and soil conditioning.