* Chemical rocks are formed by the precipitation of minerals from a solution. Examples include rock salt (halite) and gypsum.

* Limestone is primarily composed of calcium carbonate (CaCO3), which is formed by the accumulation of the biological remains of marine organisms like shells, corals, and algae.

Therefore, limestone is classified as a biochemical sedimentary rock.

While the chemical composition of limestone is important, the primary factor in its formation is the accumulation of biological materials.