Asbestos is a naturally occurring mineral.
It is distinguished from other minerals by the fact that its crystals form long, thin fibers. The most common way for asbestos fibers to enter the body is through breathing. In fact, asbestos containing material is not generally considered to be harmful unless it is releasing dust or fibers into the air where they can be inhaled or ingested. Asbestos is most hazardous when it is friable. Sprayed on asbestos insulation is highly friable.