About asbestos
Asbestos is a generic name referring to a number of naturally-occurring minerals with fibrous and silicate characteristics. The asbestos group of minerals is significant in many ways, not least because of its existence in as much as two-thirds of the earth’s crust.
There are six commonly used asbestos types which can be categorised as falling into one of two defined groups: serpentine and amphibole.
Table 1. Asbestos groups
| Serpentine | Amphibole |
| chrysotile |
amosite |
| |
crocidolite |
| |
tremolite |
| |
actinolite |
| |
anthophyllite |
Serpentine asbestos
Chrysotile is the only serpentine asbestos and is often referred to as white asbestos because of its colour. Its fibres are curly hence the term 'serpentine' which means snakelike. It is regarded as the least dangerous of the asbestos types and is still used in many countries.
Chrysotile can be woven and is often used to make fireproof textiles such as fireblankets, oven seals and ropes. But by far its most common use (and the most common use of any asbestos type) is as a binding agent in liquids such as cement, plastic and resins. Its incredible strength brings lasting stability to these compounds which were used to produce cheap, light and heat and chemical resistant building materials such as roof sheets, cement board panels, floor tiles, guttering and roof tiles.
Amphibole asbestos
Amphibole asbestos fibres are sharp and staight and they are considered to be more dangerous because of their tendancy to pierce and imbed themselves in the linings of the lungs. As you can see in the table there are several different types but most commonly used are Crocidolite (blue asbestos) and Amosite (brown asbestos). The other types are rarely found but should be treated as blue asbestos when assessing risk.
Amphibole asbestos is commonly used in heat resistant products such as pipe insulation, insulating board, sprayed asbestos coating, underfloor insulation and firedoors. asbestos insulation board (AIB) is occasionally found in older homes where it was often used in garage ceilings, soffit boards and as infill panels.
Chemical makeup
Serpentine asbestos has a chemical formula of Mg3Si2O5(OH)4 and amphibole asbestos has a basic structure as follows: (Si4O11)-6.
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