Used to make smoke comps, thermites. From Wikipedia: Self-heating cans of military food rations developed during WWII used a thermite-like mixture of 1:1 iron (II,III) oxide and calcium silicide. Such mixture, when ignited, generates moderate amount of heat and no gaseous products. Calcium disilicide (CaSi2) is an inorganic compound, a silicide of calcium . It is a whitish or dark grey to black solid matter with melting point 1033 °C (1891.4 °F). It is insoluble in water, but may decompose when subjected to moisture, evolving hydrogen and producing calcium hydroxide. It decomposes in hot water, it is flammable and may ignite spontaneously in air. In pyrotechnics, it is used as fuel to make special mixtures, e.g. for production of smokes, in flash compositions, and in percussion caps. Specification for pyrotechnic calcium silicide is MIL-C-324C. In some mixtures it may be substituted with ferrosilicon. Silicon-based fuels are used in some time delay mixtures, e.g. for controlling of explosive, hand grenades, and infrared decoys. Smoke compositions often contain hexachloroethane; during burning they produce silicon tetrachloride, which, like titanium tetrachloride used in smoke-screens, reacts with air moisture and produces dense white fog. Gum arabic is used in some mixtures to inhibit calcium silicide decomposition.