Abstract: Asphalt roofing material is made fire-retardant by inclusion of a layer of intumescable hydrated soluble silicate particles. Preferred soluble silicate particles carry a protective moisture-resistant coating which increases the life of the roofing material, and also makes possible convenient manufacture of the particles. The protective coating includes a metal cation capable of reacting with the silicate ion of the core particle to form a reaction product that is less soluble than the core particle. The reaction is believed to seal any openings in the protective coating, thereby lengthening the effective life of the coating. Besides utility in roofing materials, the coated particles are useful as fire-retardant additives in many other products, including polymeric articles, sheet materials, coating compositions, etc.