The Raw Material

• The six mineral combinations known as asbestos consist of silicates---long chains of oxygen and silicon atoms---mixed with metallic atoms such as magnesium, according to the United States Geological Survey (USGS). Five minerals, actinolite, amosite, anthophyllite, crocidolite and tremolite, are classified as amphibole asbestos and have stiff, strong fibers. The sixth form, chrysotile, is a serpentine asbestos, which has softer and more flexible fibers; most asbestos made today is chrysotile. The material is made up of fibrous strands that divide and subdivide until the filaments are microscopic.
  
  

Mining and Separation

• Miners finds chrysotile with a magnometer, which detects magnetic minerals found near asbestos formations, then drill to pinpoint the deposit location. When the ore is mined, it usually contains no more than 10 percent asbestos, which must be separated without damaging the fibers. This is usually done by dry milling, in which the ore is crushed into small fragments; then the fragments are placed on a filter and the asbestos fibers are vacuumed out. This is repeated several times to remove all the asbestos and separate the fibers. Dry milling removes the longest fibers first, then shorter ones on later cycles.
  
  

Classification

• The USGS says chrysotile asbestos fibers are usually graded by the Quebec Standard Test. This test classifies fibers in nine grades, with one as the longest and nine as the shortest fiber. Grade one fibers are more than 3/4 inch in length. Most asbestos fibers fall into grades three through nine.
  
  

Industrial Applications

• According to the USGS, there are multiple methods for turning asbestos fibers into useful products:
  
  •Spraying loose fibers onto pipes or walls to create an insulating coating
  •Incorporating the fibers into other fiber products, such as felts for roofing or flooring, or asbestos yarn or rope
  •Reinforcing plastic products such as PVC or nylon
  •Mixing with thermoplastic resins to create automotive and electronic products, or with natural resins to create other products
  
  

Asbestos Cement

• By mixing asbestos into cement, manufacturers create a product that has the strength of regular cement without the weight. Most of the world's mined asbestos has been used in cement, according to the USGS. Asbestos cement is lighter than regular cement but just as strong, and has been used to make blocks, pipes and asbestos roofing shingles.