Types of Asbestos
Asbestos is a naturally-occurring mineral that can literally be found in a variety of shapes, sizes, and colors. While the term "asbestos" refers to the mineral type in general, a total of six different kinds of asbestos have been identified throughout the world. It's often helpful to refer to a specific type of asbestos by its sub-category because some varieties are more dangerous than others.
The six types of asbestos identified thus far each belong in one of two categories: serpentine or amphibole asbestos. The aptly-named serpentine variety is characterized by curly fibers while amphibole asbestos possesses thin, straight fibers organized in a chain-like sequence. Serpentine is thought to be much less dangerous than amphibole asbestos.
Currently, the only identified form of serpentine asbestos is chrysotile. The other five types - crocidolite, amosite, anthophyllite, tremolite, and actinolite -- all belong to the more dangerous amphibole category. Chrysotile, crocidolite, and amosite have been used for a variety of industrial applications while the remaining three types are very rare and seldom found.
Chrysotile
Chrysotile is the most commonly used type of asbestos and has been commercially mined since the 1800s. There has long been disagreement as to whether or not this form of the mineral is dangerous. Most scientists and health professionals say it is; countries that continue to mine chrysotile, like Canada and Russia, insist that it presents no danger to those exposed to it. However, surveys show that those who mine this variety of asbestos have a high incidence of asbestos-related disease.
The vast majority of chrysotile or "white" asbestos mined today is used in the manufacture of chrysotile-cement, formed into pipes, sheets and shingles. Friction products, such as disk pads, brake shoes, and clutches may also contain chrysotile. Some countries have also traditionally used this variety of asbestos to strengthen their roads by mixing it with asphalt.
Crocidolite
Fibers taken from crocidolite asbestos are very sharp and thin and quite easy to inhale. It is considered to be the most hazardous of all amphibole asbestos types. As a matter of fact, studies have shown that about one-fifth of all individuals involved in the mining of crocidolite asbestos have died of mesothelioma.
Mined in Western Australia, South Africa, and Bolivia, crocidolite, or "blue asbestos", has a lower resistance to heat than chrysotile so it was not often used as an insulator but instead as a strengthener for items such as asbestos-cement pipes and other similar products.
Amosite
Known as "brown asbestos", amosite is considered nearly as hazardous as crocidolite. Also mined in South Africa, amosite was once the second most prevalent type of asbestos found in building materials. At one time, it represented about 5% of all asbestos used in factories and other commercial buildings. It was generally used as a fire retardant in thermal insulation products. This form of asbestos is known to be highly friable and its tendency to crumble makes it particularly hazardous as fibers are easily released and inhaled.
Which Ones are Dangerous?
While it's true that the amphibole form of asbestos is more dangerous than the serpentine, it still stands that exposure to any type of asbestos for any amount of time is hazardous and should be avoided at all costs. If you must work with asbestos in old buildings, ships, cars, etc., always wear a face mask or respirator and change clothes before returning home so that asbestos dust does not spread to your family.