The answer is asbestos. Asbestos is a group of naturally occurring silicate minerals, and have found use in electrical insulation for hotplate wiring and in building insulation, because of its insulating properties, strength, affordability and resistance to fire. However, asbestos has been linked to serious health effects. The inhalation of asbestos fibres has been linked to asbestosis, which is progressive fibrosis of the lungs, resulting in significant lung damage.