At room temperature, calcium is found in a solid state. It appears as a silvery white compound that tarnishes easily in contact with air. Calcium melts at a temperature of 1,547.6 F and boils at 2,703.2 F.
In nature, calcium is present in various combinations. Calcium carbonate serves to produce slaked lime, a compound widely used in the chemical industry. Calcium nitrate has important fertilizing properties. Calcium phosphate plays an important part in the human body, as it is the main substance found in bones. Calcium sulphate, also known as gypsum, is used in medicine for immobilizing fractured bones during the healing process.