Asbestos is a naturally occurring mineral that has been mined for thousands of years. Unfortunately, it was not until the middle of the 20th century that the carcinogenic properties of asbestos became part of the public consciousness. Extreme precautions should be taken any time asbestos is disturbed, as a single fiber can progress into a terminal disease over the course of decades.
The United States Environmental Protection Agency (EPA) defines six different types of asbestos minerals that fall into two distinct categories. One class of fibers are referred to as serpentine because they are curly. Chrysotile are the only asbestos fibers classified as serpentine. The remaining five asbestos minerals are considered to be part of the amphibole class, which are needle-like in shape. Amosite, crocidolite, tremolite, anthophyllite and actinolite are the five asbestos minerals that are classified as amphiboles.
The vast majority of commercial asbestos is chrysotile, also known as “white asbestos”. Because the nature of chrysotile is more flexible than any of the other types of asbestos, it was often spun and woven into fabric. Additionally, chrysotile was used for cement roofing, floor and wall panels, joint compound, brake linings, pipe insulation and many other commercial products.
Of the six types of asbestos minerals, crocidolite is the most harmful type. Also known as “blue asbestos,” crocidolite does not resist heat as well as other types of asbestos, which, thankfully, explains why manufacturers used crocidolite less than other types of asbestos.
Unlike crocidolite, amosite, also known as “brown asbestos,” is very fire retardant and so it was used in many thermal insulation products and ceiling tiles. Largely found in South Africa and considered more toxic than chrysotile, amosite fibers are shorter and straighter than chrysotile fibers.
The remaining three types of asbestos as classified by the EPA are not nearly as prevalent in commercial products as are chrysotile, crocidolite and amosite. However, tremolite is responsible for contaminating a vermiculite mine in Libby, Montana, which to this day is one of the worst environmental disasters in U.S. history.
What is Asbestos?