Asbestos and Your Health
What Is Asbestos?
Asbestos is the name given to a number of naturally occurring fibrous silicate minerals that have been mined for their useful properties, such as thermal insulation, chemical and thermal stability, and high tensile strength. In the past, asbestos was added to a variety of products to strengthen them and to provide heat insulation and fire resistance. The three most common types of asbestos are: a) chrysotile b) amosite, and c) crocidolite. Chrysotile, also known as "white asbestos" and a member of the Serpentine mineral group is the most common. Asbestos can only be identified under a microscope. (So don't let any Realtors tell you there's no asbestos in an older house you want to buy - unless they can prove they have microscopic vision!)
Asbestos differs from other minerals in its crystal development. The crystal formation of asbestos is in the form of long thin fibers. Asbestos is divided into two mineral groups - Serpentine and Amphibole. The division between the two types of asbestos is based upon the crystalline structure. Serpentines have a sheet or layered structure where amphiboles have a chain-like structure. As the only member of the serpentine group, Chrysotile (A, B) is the most common type of asbestos found in buildings. Chrysotile makes up approximately 90%-95% of all asbestos contained in buildings in the United States.
In the amphibole group, there are five types of asbestos. As an acronym for the Asbestos Mines of South Africa, Amosite is the second most prevalent type of asbestos found in building materials. Amosite is also known as "brown asbestos. " Next, there is Crocidolite or "blue asbestos," which is an asbestos found in specialized high temperature applications. The other three types, Anthophyllite, Tremolite and Actinolite, are rare and found mainly as contaminants in other minerals. Asbestos deposits can be found throughout the world and are still mined in Australia, Canada, South Africa, and the former Soviet Union.