Physical properties
Asbestos is the fibrous form of the mineral magnesium silicate, and has been mined in many parts of the world including Canada, Russia and some African states. Its value lies in its physical properties, mainly its insulation (thermal and electrical) qualities, its tensile strength, its resistance to corrosion and, because of its fibrous structure, its ability to form very strong materials when combined with other components (eg: cement). This fibrous nature has also enabled asbestos to be woven in to fabrics, allowing the creation of gaskets, fire blankets and safety curtains. It is of course, also very cheap!
Asbestos becomes useable after mining when the rock is crushed until the fibres become fine and small. The fibres themselves have two different forms:
Serpentine
Amphibole
All forms of asbestos are amphibole with the exception of chrysotile, which is serpentine. Six main forms exist (see History), all with slightly different properties.
For a fibre to be “respirable” it must have a length greater than 5 microns, a width less than 3 microns, and a length of at least 3 times its width. Most asbestos fibres fall within this category, and hence the Health Issues.
So called because the fibres are curly and snake shaped. They are longer and more flexible than amphibole fibres, and are therefore easier to form in to woven fabrics.
Fibres are straight, needle like and lacking in flexibility
