Cobalt silicide, also known as "cobalt monosilicide." Cosine of I. Molecular weight 87.03. Rhombic crystal. Melting point 1395℃, relative density 6.3. Soluble in hydrochloric acid, insoluble in sulfuric acid. It can be eroded by aqua regia, concentrated nitric acid, strong alkali solution, and molten hydroxide and carbonate. It can react with hydrogen sulfide, hydrogen fluoride, hydrogen chloride, fluorine, and chlorine.