Chrysotile is an asbestiform sub-group within the serpentine group of minerals. There are three known species of chrysotile: clinochrysotile (which is monoclinic), orthochrysotile (which is orthorhombic) and parachrysotile (which is also an orthorhombic polymorph). These varieties are all phyllosilicates. The chemical formulae for the three are the same: Mg3(Si2O5)(OH)4 with variable iron as Fe2+ substituting for magnesium. Chrysotile varies in color from gray-white to golden yellow to green. It has a hardness of 2.5 - 3. The three varieties form the fibrous members of the serpentine group and have been extensively mined as asbestos.
Chrysotile serpentine from the Salt River area ArizonaClinochrysotile is the monoclinic form of chrysotile and likely the most common variety. Like the other two species of chrysotile (orthochrysotile and parachrysotile) it is very difficult to distinguish from the other species. Its type location is unknown although the chrysotile from Asbestos, Quebec, Canada is largely clinochrysotile.
Orthochrysotile is the orthorhombic form of chrysotile and is more common than the other orthorhombic form parachrysotile. Like the other two species of chrysotile (clinochrysotile and parachrysotile) it is very difficult to distinguish from the other species. Its type location is found in Silesia.
Parachrysotile is a second orthorhombic form of chrysotile. Like the other two species of chrysotile (orthochrysotile and clinochrysotile) it is very difficult to distinguish from the other species. Its type location is Québec, Canada.
Chrysotile, a form of asbestos, is a proven human carcinogen (List of IARC Group 1 carcinogens). It is known contributor to mesothelioma. However, unlike other asbestos forms of asbestos such as crocidolite and amosite, Chrysotile only poses a risk when absorbed in extreme quantities. This is due to the fact that Chrysotile is a rolled phyllosilicate, whereas other asbestoform minerals are bladed amphiboles. These blades become imbeded in lung tissue upon inhalation, and serve as a constant irritant until the tissue becomes cancerous. Chrysotile is much more flexible than amphibole asbestos, and does not cause cancer in the same manner. Instead, the risk posed by Chrysotile in large quantities is similar to silicosis caused by inhalation of fine grained quartz. However, EPA and OSHA guidelines do not distiguish between phyllosilicate and amphibole asbestoses.