Abstract: Structures of inorganic fibers which may contain inorganic particles, flakes or powders, are prepared by adding aqueous silicone resin emulsions containing curing catalysts and emulsifiers to the fiber material, shaping the treated fiber material, and subsequently curing the silicone resin, in which salts or chelates of trivalent iron are employed as the curing catalysts. Iron (III) acetylacetonate is preferably employed as the curing catalyst. The structures are preferably produced in a continuous process in which the aqueous silicone resin emulsion is sprayed onto the fiber material, then the fiber material is compacted to the desired bulk density and the silicone resin is cured by contacting the compacted fiber material with hot gases. Curing of the silicone resin is preferably carried out at a temperature of from 150.degree. to 300.degree. C. over a period of from 5 to 8 minutes.