Rock Phosphate

It is a lithophile element due to its high affinity for oxygen. In addition, it has biological importance due to that it is an important structural element of living bodies such as C, H, N, O. For these reasons, it is never present free in nature; It is present as salts and esters of phosphoric acid.

Rocks containing phosphate minerals in sufficient purity and amount are called phosphate or phosphate rock. Classification of phosphate rocks is made according to the value of P2O5 percentage in it. This value varies between 4% and 42%. Although, rocks containing 20% or more P2O5 are called phosphate rocks.