Introduction - the asbestos minerals and their uses

Asbestos is the term for the fibrous form of a number of naturally occurring crystalline silicate minerals, which have been exploited commercially and are still mined and processed in various countries such as South Africa, Canada, the Former Soviet Union and China. The three main types of asbestos that have been commercially produced are Chrysotile, Amosite and Crocidolite, which are commonly referred to as White, Brown and Blue asbestos respectively. Other rarer forms of asbestos include Tremolite, Anthophyllite and Actinolite, which may be found either individually or as contamination within the three main types. 

All of the above forms of asbestos belong to either the Serpentine or Amphibole mineral groups and have different chemical compositions and hence different associated properties. All have excellent heat insulating properties and are relatively incombustible, whilst some are flexible or have high tensile strengths, or resistance to acids and alkalis. 

The properties of asbestos have been known for thousands of years, with one of the earliest recorded uses of asbestos being by Finnish Potters who used it to strengthen their clay over 4000 years ago. It is also recorded that the Egyptians and Romans shrouded their dead in asbestos cloth, and the Greeks and Romans made asbestos lamp wicks that apparently seemed to burn forever. 

It is estimated that around six million tonnes of asbestos has been imported into the UK (DETR 1999), however the importation and use of Amosite and Crocidolite were prohibited in the UK in 1986 and Chrysotile was prohibited in November 1999, except for specialised applications such as high pressure steam gaskets etc. most of which will probably be discontinued by 2005. It should also be noted that the trade in, re-use or gifts of ACMs was also prohibited in 1999 and this includes asbestos cement roofing sheets that were previously often re-used when outbuildings were moved or altered. 

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