Asbestos is a group of naturally occurring fibrous minerals. There are six identified types of asbestos that belong to the amphibole and serpentine mineral families.
Amphibole Mineral Family
Five types of asbestos belong to the amphibole family. These varieties have sharp, straight chain-like structures that are easily inhaled.
Amphibole asbestos includes:
- Actinolite asbestos
- Amosite asbestos
- Anthophyllite asbestos
- Tremolite asbestos
Actinolite asbestos is generally dark in color and has sharp, needle like fibers that when airborne, can be easily inhaled. Actinolite is made up of other minerals including calcium, magnesium, iron, and silicon. Actinolite was previously used in products such as cement, insulation materials, paints, sealants and drywall.
Amosite asbestos, also known as brown asbestos, is considered one of the most hazardous types of asbestos. Primarily mined in South Africa, amosite is characterized by sharp, brittle, needle-like fibers that can be easily inhaled. Amosite makes up about five percent of asbestos materials used in buildings in the United States making it the second most commonly used type of asbestos next to chrysotile.
Amosite can be found in the following products:
- Chemical insulation
- Electrical insulation
- Fire protection
- Insulation boards
- Plumbing insulation
- Thermal insulation
Like other types of asbestos in the amphibole family, anthophyllite is composed of long, needle-like fibers that can be easily inhaled into the lungs. Anthophyllite can range from brown to yellowish in color and is composed mainly of magnesium and iron. One of the more rare forms of asbestos, anthophyllite was not used as often in consumer products, but can be found in some cement and insulation materials.
Crocidolite asbestos, also known as blue asbestos, is considered the most hazardous type of asbestos in the amphibole family. Crocidolite is made up of extremely fine sharp fibers that are particularly easy to inhale. Studies show that crocidolite is so hazardous, it may be responsible for more illnesses and deaths than any other type of asbestos.
Crocidolite was rarely used in commercial products because it was found to be much less heat resistant than other types of asbestos. Crocidolite was used in products such as cement, tiles and insulation materials.
Tremolite asbestos is known for its heat resistant properties and can also be woven into fabric. Like other asbestos in the amphibole family, tremolite has sharp fibers that can easily be inhaled or ingested. Tremolite is no longer mined and is responsible for many cases of asbestos-related cancer and asbestos diseases. Tremolite ranges in color from a milky white to a dark green and is found in other minerals such as talc and vermiculite. Tremolite was previouslyused in a variety of products such as paint, sealants, insulation, roofing and plumbing materials.
Serpentine Mineral Family
Chrysotile asbestos is the only known type of asbestos that belongs to the serpentine family. Also known as white asbestos, this variety is made up of curly fibers and has a layered structure.
Chrysotile asbestos is the most commonly used variety of asbestos, comprising 90 to 95 percent of asbestos used in buildings in the United States. Hailed for its heat resistant properties and flexible fibers that can be woven into fabric, chrysotile asbestos is used in a variety of asbestos insulation and fireproofing products.
Chrysotile can be found in the following products:
- Brake lining
- Brake pads
- Disk pads
- Roofing materials
Still mined today in Canada, Russia and Italy, there is continuing controversy between health care professionals and the companies that continue to export it. These companies claim that the chrysotile mined today is safe because it is only used in dense and non-friable products and is "encapsulated in a matrix of either cement or resin." Health care professionals maintain that all forms of asbestos are a carcinogenic and no level of exposure is safe. Because it is the most widely used, chrysotile accounts for the majority of cases of mesothelioma and asbestos diseases including pleural mesothelioma.