Calcium Metal

Pure metal calcium was rarely used in industry until recently, but is being used to a greater extent as a deoxidizer for copper, nickel and stainless steel. Since calcium hardens lead when alloyed with it, calcium alloys are excellent for bearings, superior to the antimony-lead alloy used in battery grids, and more durable as a coating on lead-covered cable. Calcium, chemically combined, is present in lime (calcium hydroxide), cement and mortar, teeth and bones (as calcium hydroxyphosphate).

The alkaline earth metals, among which are calcium, do not exist free in nature; on the other hand, its carbonates and sulphates are found in relative abundance.

Calcium carbonate, CaCO3, comes in multiple forms: limestone, eggshell, shells, pearls, corals, and chalk (made up largely of shells of tiny organisms called foraminifera), in which the crystalline character has almost disappeared ; marble, Iceland spar, stalactites, stalagmites, limestone spar, and dog's tooth spar, crystalline forms of calcite, and another crystalline variety, aragonite.

Calcium Metal is also found as hydrated sulfate, CaSO4. 2H2O, gypsum. When the crystals are very small and the whole mass has a fine texture, it is called albastro, and it is used for ornamental purposes. The anhydrous form of calcium sulfate is found as the anhydrite mineral CaSO4.