Calcium Calcium Calcium is a chemical element with symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The
Calcium gluconate one-gram vial, 10 ml of 100 mg/ml (10% solution). In the United Kingdom this amount costs the NHS about 0.65 pounds. 10% calcium gluconate solution (given intravenously) is the form of calcium most widely used in the treatment of low blood calcium. This form of calcium is not as well absorbed as calcium lactate, and it only contains 0.93% (930 mg/dl) calcium ion (defined by 1 g weight solute in 100 ml of solution to make 1% solution w/v). Therefore, if the hypocalcemia is acute and severe, calcium chloride is given instead. Calcium gluconate is used as a cardioprotective agent