Asbestos is the name for a group of naturally occurring silicate minerals that can be separated into fibers. The fibers are strong, durable, and resistant to heat and fire.
There are several types of asbestos fibers, of which three have been used for commercial applications: (1) Chrysotile, or white asbestos, comes mainly from Canada, and has been very widely used in the US. It is white-gray in color and found in serpentine rock. (2) Amosite, or brown asbestos, comes from southern Africa. (3) Crocidolite, or blue asbestos, comes from southern Africa and Australia.
Amosite and crocidolite are called amphiboles. This term refers to the nature of their geologic formation.
Other asbestos fibers that have not been used commercially are tremolite, actinolite and anthophyllite, although they are sometimes contaminants in asbestos-containing products.
MSHA's Personal Asbestos/fiber Compliance Air Sampling Results
January 2000 through December 2003
The data below represents MSHA's airborne asbestos monitoring experience for the years 2000 through 2003. Each Excel workbook contains spreadsheets for the personal samples collected during that calendar year. With the exception of the data base explanation document, the following files are all Microsoft Excel®.
Asbestos Page - The California Geological Survey (CGS) provides information on the geology of asbestos occurrences in California to a number of state, local and federal agencies, private industry, consultants and the public.