Asbestos fibers cannot be seen without a special microscope. Analysis by an accredited testing laboratory is the only way to know for certain whether a material contains asbestos.
The EPA requires that the asbestos content of suspect materials be determined by analyzing samples with polarized light microscopy (PLM). PLM analysis results give the percent and type of asbestos in the sample. The asbestos content of manufactured items ranges from one percent to 100 percent.
The major forms of asbestos used commercially were chrysotile, amosite and crocidolite. Tremolite, anthophyllite and actinolite are of less commercial value. Asbestos containing materials (ACM) are mixtures of individual asbestos fibers and binding material.
Chrysotile is the most common type of asbestos found in buildings. Also known as "white asbestos," chrysotile makes up approximately 90%-95% of all asbestos contained in buildings in the United States.
Amosite is the second most prevalent type of asbestos found in building materials. Amosite is also known as "brown asbestos."
Crocidolite or "blue asbestos," is found in specialized high temperature applications.