The chemical formation of limestone occurs in caves. Water can enter a cave through fractures or pore spaces in the cave’s ceiling. When this happens, it might hang on the ceiling or drop directly to its floor. When the drop hangs onto the ceiling and evaporates, it leaves behind the dissolved calcium carbonate that it carried. As the water continuously enters the cave, more and more calcium carbonate is collected on the same spot. Eventually, this will cause CaCO3 to collect enough that limestone is formed. The proper name for this cave formation is stalactite. There is also another way that limestone forms chemically, and that is when the drop of water falls to the floor. The formation of a stalagmite (basically an upside down stalactite) happens when the water that sits on the floor dissolves. The only difference in both chemical formations is where the water evaporates and leaves the CaCO3.
