What is Abestos?
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. The three most common types of asbestos are:
- Chrysotile
- Amosite
- Crocidolite
Chrysotile, also known as white asbestos and a member of the Serpentine mineral group is the most common. Asbestos can also be identified under a microscope.
White (Chrysotile) asbestos still mined in Canada and exported to developing countries (see image).
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 America, 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, 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.