Metals preparation, metallurgy
Cable coating, batteries
Chemical fertilizers
Gibsum, concrete

Calcium has significant applications in the production of alloys with lead and aluminum, and in the industrial production of metals from its oxides. It is also used as deoxidizer with iron, steel, copper and its alloys.

Calcium carbonate is the most important of all calcium compounds. It appears in colorless crystals, like calcite, which has birefractivity properties, or in other crystalline form, as aragonite. It is the major constituent of pearls and sea shells, being present in calcareous formations of caves. For use in the chemical industry most calcium carbonate is first converted to lime by an heating process. This lime can origin cement if mixed with water and sand. The heating of calcium oxide in an electrical oven with oven-coke produces calcium carbonate also called "carbite". This can react with water to origin acetylene, one of the most important compounds in organic chemistry.

Calcium sulfide occurs in nature as the mineral anhydrite, crystallized in rhombic prisms. Calcium metaphosphate is used as a mild abrasive and as neutralizing agent in toothpastes. The monobasic phosphate is used as fertilizer, and calcium chloride when mixed with ice is an excellent freezing and exsiccation agent.

Calcium fluoride, constituent of fluorite, is used as a flux, but, more important, is the source of hydrofluoric acid made by the action of sulfuric acid on fluorspar.

Calcium "hipocloride" is used as decolorizer, oxidizer or disinfectant.