Asbestos is the common name given to a group of naturally occurring mineral silicates that can be separated into flexible fibers. The name Asbestos comes from the Greek word meaning “Inextinguishable”.
There are two main mineralogical classifications of Asbestos;
Serpentine Asbestos - The serpentine family consists of only chrysotile or “white” Asbestos only. It is a hydrated magnesium silicate having long wavy fibers that are white or off-white. Chrysotile has a layer type of structure, having fibers that are very flexible, paralleling growth. The fibers are strong, easily separable, and have a silky luster. Chrysotile is rarely brittle and basically brownish in colour. It is the most common variety of Asbestos and is widely distributed geographically. The largest deposits are in Canada, Russia and Rhodesia.
Amphibole Asbestos - Within the amphibole family, only amosite and crocidolite have had significant commercial use. Amosite is often called “brown” Asbestos and has much straighter and shorter fibers than chrysotile. Amosite is a fibrous variety of the mineral grunerite, a ferrous magnesium silicate mined only in South Africa. Amosite can readily be broken down into long, somewhat harsh, strong, stiff fibers that range in colour from a brownish-yellow to almost white, depending on the quality. Crocidolite is referred to as “blue” Asbestos and has long straight fibers much like Amosite. Croidolite also referred to as blue Asbestos, has a flexible silky fiber and is blue green in colour. It is the fibrous form of riebeckite and has a fine, resilient fiber characteristic. It was mined commercially in Africa and Australia.
Asbestos is found in veins in the host rock and is produced in a commercially useful form by open pit mining and successive stages of crushing and aspiration of the ore. The fibers are then sealed in plastic bags for use in the manufacture of products containing Asbestos. The chrysotile form accounts for approximately 90 percent of current world consumption.
Asbestos and its beneficial properties were well recognized before our age of technology. This mineral’s characteristics, it unique fiber complication which lends to its high tensile strength, resistance to wear and high temperatures, and the fact that it is literally present, at man’s doorstep, readily suggests useful applications. Asbestos containing materials date back to 2500 BC, when in Finland, it was incorporated into clay pots as a binder for added strength. In the same era , the Egyptians create burial shrouds to protect the ashes of their dead. The Greeks and Romans used Asbestos in lamp wicks and woven cloth. They learned that soiled cloths of Asbestos could be cleaned by throwing them into a fire.
Asbestos fibers were widely used in many products and materials up to and during the industrial revolution. Chrysotile ore deposits were discovered in many parts of Canada and were first mined in 1876. Russia followed with mining in the late 1880’s. The industrial and commercial value started the development of these mines. The manufacturing industry required wool and cotton products that were non-combustible and fire resistant. These large factories were set-up in England and France to produce products and materials that would be used in the machinery for greater strength and the capability to withstand heat and friction.
