Zinc nitrate is a colorless crystalline solid. Noncombustible, but accelerates the burning of combustible materials. If large quantities are involved in a fire or the combustible material is finely divided, an explosion may result. Prolonged exposure to fire or heat may result in an explosion. Toxic oxides of nitrogen are produced in fires involving this material. It is used as a catalyst in the manufacture of other chemicals, in medicine, and in dyes.