Here's how it works:
* Marine Organisms: Many marine organisms, like corals, mollusks, foraminifera, and algae, use calcium carbonate (CaCO3) to build their skeletons and shells. This calcium carbonate is primarily in the form of calcite.
* Death and Decay: When these organisms die, their hard parts settle to the ocean floor.
* Accumulation: Over time, the accumulation of these skeletal and shell fragments forms a thick layer of sediment.
* Lithification: This sediment undergoes a process called lithification, where it is compacted and cemented together by minerals, primarily calcite.
* Limestone Formation: The resulting rock is known as limestone, primarily composed of calcite derived from the organic remains.
Therefore, organically formed limestone is essentially a collection of ancient marine life, with calcite being the main mineral component sourced from their hard parts.
