Types of Asbestos

The six types of asbestos can be further divided into two main categories - serpentine and amphibole - based on the structure of the asbestos as seen under a microscope.

Serpentine asbestos has a layered structure with curly fibers. The only type of asbestos in this category is Chrysotile. Chrysotile is the type of asbestos that was most often used in buildings in the United States.

Amphibole asbestos is characterized by long chain-like fibers that are sharp and easy to inhale. Crocidolite, amosite, anthophyllite, tremolite, and actinolite asbestos types fall under this category.

The following paragraphs summarize the different types of asbestos and their characteristics.

Amosite asbestos was at one point the second most commonly used type of asbestos in the United States. Amosite asbestos was traditionally used as insulation in buildings and factories. It has been banned in most countries for the last thirty years.

Crocidolite asbestos makes up only about four percent of the asbestos used in the United States. Crocidolite asbestos is harder and more brittle than any other type. It is the most deadly type of asbestos because of its needle-like fibers. Crocidolite asbestos was mined overseas. The percentage of the miners who developed asbestos-related cancer from the mines is eighteen percent.

Chrysotile asbestos is the only type of asbestos that is still mined today. Because it was the most widely used type of asbestos, most of the health problems can be attributed to its effects. Chrysotile was most often used to fireproof different materials by weaving it into the fabric. Despite warnings that all asbestos types cause cancer, some still claim that Chrysotile asbestos is relatively safe. People who live near Chrysotile mines have a higher risk of developing cancer than the general public.

Anthophyllite asbestos contains iron and magnesium. Its fibers are long and flexible, and mining activities have been associated with various respiratory disorders.

Tremolite asbestos is composed mostly of magnesium and can be either white or dark green. Tremolite asbestos is common in vermiculite, and is definitely associated with the development of mesothelioma.

Actinolite asbestos is also made mostly of magnesium, and occurs in a range of colors. Actinolite is very rare, so it was not used in products as commonly as the other forms of asbestos. Actinolite asbestos is most often present in metamorphic rock.

To learn more about Asbestos Awareness visit our Cal/OSHA Asbestos Awareness Online Training web page.