The variability in deposition environment and the depth of its location in the quarry mean that limestones show significant variation at different places. For the cement producers, this presents challenges to obtain a uniform raw material supply.
Cement clinker is made primarily from naturally-occurring raw materials, the highest proportion of which is limestone. Most limestones were formed in a marine environment, where a variety of creatures lived and died, leaving their skeletons behind. The skeletons frequently formed a porous framework into which came incursions of silt or clay from rivers flowing to the sea. The irregular nature of these events means the chemical composition of limestone from one place to another is not the same. Natural variation will always be apparent.
