Asbestos is a naturally forming mineral, which has been commercially mined for its useful properties, namely:
- Resistance to chemicals and heat
- Low thermal conductivity
- Flexibility
- High tensile strength
Asbestos was seen as a miracle fibre which could be bonded into various building materials and woven into textiles. It still remains one of the most effective forms of fire protection known to man and, in many cases, asbestos materials remain in good condition for many decades.
It is estimated over five million tonnes of asbestos was imported into the United Kingdom, mainly from Canada or South Africa. The three types mainly used within the construction and refurbishment of buildings are:
Chrysotile
Commonly known as ‘white’ asbestos, Chrysotile is a member of the group of minerals known as serpentine. In its raw natural state Chrysotile is cream, white or pale green in appearance and its soft curly fibres when processed make it ideal for spinning and weaving.
Chrysotile asbestos was the most commonly used form within the UK used in asbestos cement products and other various materials and papers.
Amosite
Referred to as ‘brown’ asbestos, Amosite is the most common member of the amphibole group and was commercially mined in South Africa. When raw, the fibres are brown or black and when processed appear to be grey or brown.
Typical applications for brown asbestos were pipe lagging or mixed as Asbestos Insulation Board (AIB).
Crocidolite
Crocidolite is another member of the amphibole group and commonly known as ‘blue’ asbestos. It was primarily mined in South Africa but was also mined commercially in Australia.
Commonly used as sprayed insulation, Crocidolite is seen as one of the most deadly forms of Asbestos. In its raw state the fibres are very dark in appearance and when processed appear a distinctive blue.
One important point to note is that although the forms of asbestos are commonly referred to by colour, this does not prove an ideal way to identify the material.
An additional three forms of mined asbestos are:
Anthophylite, Tremolite & Actinolite
These forms are quite rare and are only very occasionally found within the UK. They were produced in moderate quantities in South Africa, Taiwan, Korea,
Pakistan & India.