Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO3), typically formed in marine environments from the accumulation of shell, coral, algal, and fecal debris. It is a key rock in the carbon cycle and is widely used in construction, agriculture, and industry. Limestone is important in understanding sedimentary environments and the geological history of carbonates.
Reference: Tucker, M. E., & Wright, V. P. (1990). “Carbonate Sedimentology.” Blackwell Science.