Asbestos is most commonly found in three rock types: serpentinites, altered ultramafic rocks, and some mafic rocks. Other rock types known to host asbestos include metamorphosed dolostones, metamorphosed iron formations, carbonatites, and alkalic intrusions.
Where is asbestos found most?
Ambient, or background, air usually contains between 10 and 200 asbestos fibres in every 1000 litres (or cubic metre) of air (equivalent to 0.01 to 0.20 fibres per litre of air) meaning we may breath up to 5000 fibres per day. However, it is extremely rare to get an asbestos-related disease from this level of exposure.