Calcite is a transparent to opaque carbonate mineral with more than 99% purity. Mainly used in water treatment and swimming pools, it contributes to control both internal corrosion and the deposition of scale. As a neutralizing agent, filler, antacid and Source of lime.

The Langelier Index(LSI) is an approximate indicator of the degree of saturation of water with calcium carbonate. As a mechanism to stabilise and optimise water supply systems, the Langelier Index is calculated using the pH, alkalinity, calcium concentration, total dissolved solids, and water temperature.

If the Langelier Index is negative, then the water is under saturated with calcium carbonate and the distribution system tends to be corrosive. If the Langelier Index is positive, then the water is over saturated with calcium carbonate, which generates the formation of scale in the distribution system. If Langelier Index is close to zero, then the water is just saturated with calcium carbonate and will neither be strongly corrosive or scale forming.