Calcium disilicide is an inorganic compound, a silicide of calcium. It is a whitish or dark grey to black solid matter with melting point 1033 °C. It is insoluble in water, but may decompose when subjected to moisture, evolving hydrogen and producing calcium hydroxide. Decomposes in hot water. Calcium silicide is an alloy of Silicon, Calcium and Iron. It is used both in the form of powder and lumps in iron and steel industry as a powerful deoxidiser and desulphuriser, owing to the high affinity of calcium, for oxygen, sulphur and other elements. Since the density of calcium is almost 6 times less than that of iron and its boiling point is close to the melting point of steel, it is generally used as an alloy of silicon, with 28 to 32% calcium and 60 to 65% silicon. This alloy is also extensively used in the foundaries for inoculating grey cast iron and its demand in India is estimated to be in the order of 300 – 400 tonnes per annum. As it is not produced in the country, all its requirements are currently met by imports, involving a large sum of foreign exchange.