Any of several related minerals of fibrous structure that offer great heat resistance because of their nonflammability and poor conductivity.

Commercial asbestos is generally either made from serpentine ("white" asbestos) or from sodium iron silicate ("blue" asbestos).

The fibers are woven together or bound by an inert material. Over time the fibers can work loose and, because they are small enough to float freely in the air or be inhaled, asbestos usage is now strictly controlled, exposure to its dust can cause cancer.