Miscellaneous

The six recognized asbestos minerals, which are considered silicates (molecules that include silicon and oxygen), include:

• Chrysotile - (Also known as white or green asbestos, from the Greek word meaning "fine, silky hair") Appears as curly, whitish fibers and constitutes 95 percent of the asbestos in use. Chrysotile is mined throughout the world, but most of the United State's chrysotile supply comes from Canada, Africa, and former USSR. Scientists believe this to be the least toxic of all asbestos forms.
• Crocidolite - (Also known as riebeckite or blue asbestos) Composed of straight fibers, most crocidolite comes from southern Africa and Australia. It is believed to be the most toxic form of all asbestos minerals.
• Amosite - (Also known as cummingtonite-grunerite or brown asbestos) The trade name "amosite" is an acronym for Asbestos Mines of South Africa, after the Amosa mines. Amosite is also straight in shape, but brittle in structure and excellent for use in heat insulation.
• Anthophyllite - This form of asbestos is brittle, white, and contains various forms of iron. It has been found to have excellent resistance to chemicals and heat.
• Tremolite - In rough form, tremolite appears white and chalky. Tremolite can also be naturally found in other mineral forms aside from asbestiform. It has been the major ingredient in industrial and commercial talc.
• Actinolite - Typically prismatic, flat in structure, and elongated. Actinolite also comes in forms other than asbestiform and has poor resistance to chemicals.

The last five amphibole (which translates to "ambiguous" in Greek) types have a slightly more complex crystal structure than chrysotile and are not used as extensively in commercial products as chrysotile. Due to their structure, amphiboles tend to stay in the lungs longer than chrysotile and are more likely to cause illness because of this factor. Some hypothesize very small contaminations of amphibole fibers within chrysotile are most to blame for cancer deaths caused by asbestos exposure.

Asbestiform minerals are found in serpentine and ultramafic rock. These rocks are located throughout the United States, especially near mountainous regions. California is exceptionally bountiful in asbestos, where the mineral can be found in at least 44 of the state's 58 counties (some geologists report asbestos is found in 50 of the 58 counties). Asbestos fibers especially form near fault zones, where temperature, pressure, and time have transformed the molecules into the asbestiform crystals.

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