Asbestos

The term asbestos is a generic designation referring usually to six types of naturally occurring mineral fibers that are or have been commercially exploited. These fibers belong to two mineral groups: serpentines and amphiboles. The serpentine group is represented by a single asbestiform variety-chrysotile. There also are five commercial asbestiform varieties of amphiboles-anthophyllite asbestos, cummingtonite-grunerite asbestos (amosite), riebeckite asbestos (crocidolite), tremolite asbestos, and actinolite asbestos. Amosite and crocidolite are no longer mined. Nearly all of the asbestos mined after the mid-1990s was chrysotile. Only very small amounts of actinolite, anthophyllite, and tremolite asbestos may be mined in a few countries. Asbestos was mined in Argentina, Brazil, Canada, China, India, Kazakhstan, and Russia in 2010; world production was estimated to be 1.97 × 106 tons.

Properties that made asbestos valuable for industrial applications were their thermal, electrical, and sound insulation properties; inflammability; matrix reinforcement (cement, plastic, and resins); adsorption capacity (filtration, liquid sterilization); wear and friction properties (friction materials such as brakes and clutches); and chemical inertia (except in acids). These properties led to the use of asbestos in about 3,000 products by the 1960s. Since about 1995, asbestos-cement products, including pipe and sheets, accounted for more than 95% of global asbestos consumption as other uses of asbestos have declined. Global consumption of asbestos was estimated to have been about 1.98 × 106 tons in 2009. The leading consuming countries in 2009 were Brazil, China, India, Russia, and Thailand, each with more than 100,000 tons of consumption.