Asbestos Safety Manual

10 Asbestos Safety Manual Environmental Health and Safety C General Information Asbestos - Its Various Uses and Forms Asbestos is a generic term for a group of naturally occurring silicate minerals that are mined primarily in South Africa, Canada, and the former Soviet Union. Asbestos can appear in fibrous crystal form, and when crushed, separates into flexible fibers. Asbestiform minerals are divided into two groups based on their morphology. Serpentine minerals have a sheet or layered structure while amphiboles have a chain-like structure. Chrysotile, amosite, and crocidoilite are the three commercially important types of asbestos. Serpentine Minerals • Chrysotile is white asbestos with fine silky fibers. It accounts for over 90 percent of the asbestos used in the United States. Chrysotile is mined in Canada and the former Soviet Union. Amphibole Minerals • Amosite is known as brown asbestos and is used in heat insulation materials. Amosite is mined primarily in South Africa. • Crocidolite is known as blue asbestos and is occasionally found with amosite and chrysotile in pipe or boiler wrap. Crocidolite is mined in South Africa. • Tremolite, Actinolite, and Anthophyllite are rare forms of asbestos with limited commercial value, but can be found as contaminants in other building materials. Asbestosminerals have the following characteristics in common: • Separate into smaller fiber bundles when disturbed or handled. • Resistant to heat, bacteria, and chemicals. • Great tensile strength and stiffness. • Excellent electrical and thermal insulator. • Very good noise insulator. • Resistant to the effects of friction and wear. Asbestos Survey Categories The Environmental Protection Agency (EPA) has identified three categories for the purposes of evaluating asbestos-containing materials (ACM) in buildings. Surfacing Materials • Sprayed or troweled-on asbestos used for acoustical, fireproofing, or decorative purposes on ceilings, walls, and structural members. Chrysotile Amosite Crocidolite