Synthetic Vitreous Fibers

Synthetic vitreous fibers are a group of fibrous, inorganic materials that contain aluminum or calcium silicates, and are made from rock or stone, clay, slag, or glass. They do not occur naturally in the environment, but are widely used for thermal and sound insulating purposes and to reinforce other building materials. There are three categories of synthetic vitreous fibers: 1) glass fibers (fiberglass), including glass wool and continuous filament glass, 2) mineral wool, which contains stone wool and slag wool, and 3) refractory ceramic fibers.

Insulation that is used in homes and buildings is composed of synthetic vitreous fibers. Refractory ceramic fibers are not widely used for building insulation. They are used to insulate furnaces, in replacement of asbestos.