* Limestone is primarily composed of calcium carbonate (CaCO3).

* Salt is primarily sodium chloride (NaCl).

While limestone can contain small amounts of other minerals, including trace amounts of sodium, the main component of limestone is calcium carbonate, not salt.

Here's a breakdown:

* Limestone formation: Limestone forms from the accumulation and cementation of the shells and skeletons of marine organisms like coral, mollusks, and foraminifera. These organisms use calcium carbonate to build their structures.

* Salt formation: Salt is formed through the evaporation of seawater. As water evaporates, the dissolved salts become more concentrated and eventually crystallize out.

So, while both limestone and salt are found in geological contexts, they are formed by different processes and have different chemical compositions.