For a long time, a class of mineral fibers collectively known as "asbestos" was popularly used in industries ranging from shipbuilding to construction to textile production. Asbestos owed its popularity to its exceptional physical properties - heat and fire resistance, acid resistance, and general durability. It was not until the later 20th century that the downside of asbestos usage came to light: the popular material was linked to serious respiratory problems, including lung scarring, lung cancer, and mesothelioma.

In response to these health hazards, the use of asbestos became heavily regulated, and the term "asbestos" became a buzz-word in the national and international consciousness. The word "asbestos" is actually somewhat deceptive, in that it refers not to a single substance, but is actually the designation for a class of mineral fibers which share similar characteristics. Asbestos can be divided into several subtypes. Two of the most important are called "amphibole" and "chrysotile."

Amphibole Asbestos

Amphibole asbestos is a subset of asbestos fibers consisting of straight, needle-like filaments with particularly high iron content. As such, it is highly resistant to both heat and chemicals, and was valued for these properties. Amphibole asbestos was extensively used in the production of furnace and stoves, as well as being used for insulation in heating systems.

Later studies, however, found that amphibole asbestos had several characteristics which made it especially hazardous to one's health. For example, amphibole asbestos is more easily "friable," or broken up, than some other types of asbestos, making it more likely that fibers will be dispersed into the air, and subsequently inhaled. Other studies demonstrated that, once amphibole asbestos enters the lungs, it is more likely to remain there for long periods of time, causing scarring, asbestosis, and mesothelioma. Because of the high risk posed by amphibole asbestos, it has been virtually replaced by other types of asbestos in modern industry, although it may still be found in older products and buildings.

Chrysotile Asbestos

Chrysotile asbestos is described as unique among asbestos fibers because of its white color and serpentine, not straight, appearance. Unlike amphibole asbestos, chrysotile asbestos is much less friable, and thus, much less likely to enter the lungs. Because it is deemed to be a "safer" form of asbestos, chrysotile fibers are the most widely used form of asbestos today. In fact, this type of asbestos accounts for approximately 90% of all the asbestos used by US industries today. That is not to say, of course, that chrysotile asbestos is harmless, only that it carries a smaller risk than other types of asbestos.