A short encyclopedia entry on asbestus (asbestos) from Rees's Cyclopedia, treated as a mineral in chemistry and mineralogy. It describes colour, crystal forms, fracture, lustre, specific gravity, behaviour with acids and under the blowpipe, and competing chemical analyses by Bergman and Weigleb. It notes that asbestus occurs in serpentine rock and that the more flexible varieties were used to make incombustible cloth, as with amianthus.