Calcium – one of the most important elements of the human body. Overestimate the role of calcium in the life of the human body is difficult. Of elements-metals calcium is important, not only in quantitative but also in functionally. Its main location is the accumulation of the skeletal system. The very name of calcium comes from the Latin calcis – lime, "soft rock". It has been suggested that British chemist Hemfi Davy, who in 1808 received calcium metal electrochemically by electrolysis of a mixture of wet lime with mercuric oxide HgO at a platinum cathode. In nature, calcium is found in the composition of such minerals as limestone SCO3, anhydrite and gypsum CSO4 CSO4 2H2O, fluorite, CF2, apatite Ca5 (PO4) 3 (F, Cl, OH), dolomite, MgCO3 SCO3.
The share of calcium is 3.38% of the mass of the crust (5-th place in prevalence after oxygen, silicon, aluminum and iron). Due to the high reactivity calcium free form in nature is not found. Most of the calcium contained in the silicates and aluminosilicates of different rocks (granites, gneiss, etc.). In the form of sedimentary rock calcium compounds are chalk and limestone, composed mostly of the mineral calcite (CCO3). Crystalline form of calcite – marble – found in nature is much less common. Calcium is the most common major elements in the human body, most of it contained in the skeleton and teeth in the form of phosphates. Calcium compounds are found in virtually all animal and plant tissues.