Types of Asbestos
Throughout the 20th century asbestos was widely used in manufacturing and industry. Asbestos is a naturally occurring substance whose family is comprised of a variety of fibrous minerals. Exposure to these minerals has been connected to various diseases including an aggressive form of cancer known as mesothelioma. This group of minerals consists of six members divided into two categories, serpentine asbestos and amphibole asbestos.
Serpentine asbestos have curled fibers, whereas amphibole asbestos minerals are straight, narrow fibers. Members of the amphibole group constitute the most dangerous type of asbestos as the needle-like fibers can be inhaled and easily imbed themselves in various tissues of the body.
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Crocidolite
Crocidolite asbestos, commonly referred to as blue asbestos due to its coloration, is no longer a mined substance and played a somewhat minor role concerning asbestos use in the United States. Unlike other forms of asbestos, this type of asbestos does not have the same heat resistant properties and was therefore used mainly in the manufacturing of asbestos-cement. This member of the amphibole group has long hair-like fibers that penetrate the body’s tissues. Between 1900 and 2003, crocidolite asbestos use accounted for just 2.2 percent of worldwide production and consumption.
Amosite
Brown asbestos, more formally known as amosite, is another member of the amphibole group. It is considered the second most dangerous of the asbestos minerals due to the long, straight fibers that once imbedded, the body cannot expel. Like blue asbestos, this variety has been linked to the death and illness of countless miners in South Africa. This form of asbestos made up about five percent of the total asbestos use as it pertains to industry. This form of the substance has been banned in several countries; however, amosite products still remain in older buildings and can pose a hazard when the fibers become airborne.
Chrysotile
This form is the most frequently used form of asbestos and is a member of the serpentine group. This is the only commercially-used form of asbestos belonging to the serpentine family. The fibers are generally softer and less harsh than amphibole varieties, and therefore suited for uses other than those associated with the amphibole group. The use of chrysotile has spanned over two centuries, first utilized for its heat resistant properties in textiles and lamp wicks. Chrysotile continues to be mined in Canada, Russia, Italy and elsewhere, and remains at the center of heated debates concerning safety.
Actinolite
This greenish type of asbestos is most commonly found in metamorphic rocks. Its structure is reticulated long prismatic crystals and fibers it has a harsh texture and poor spinnability. This means it was not likely to be made into a cloth, unlike other forms of asbestos. This form of asbestos also possesses a poor level of flexibility, and there is not much detail available concerning its resistance to heat. Mineral impurities of this form of asbestos include lime and iron.
Anthophyllite
Anthophyllite asbestos ranges in color from grayish white to brown-gray or green, and has a lamellar or fibrous structure. It is a member of the amphibole group, and the material’s name is derived from the Latin word anthophyllum, which means clove, a reference to the most common color associated with the mineral. The luster of anthophyllite is vitreous to pearly and it possesses short fibers and a harsh texture. This form of asbestos does have spinnability and flexibility. The material’s resistance to acids, alkalies and heat are very strong, making it a natural insulator.
Tremolite
This gray-white, greenish, yellowish or bluish form of asbestos has a silky luster and is a member of the amphibole group of silicate materials. Tremolite asbestos’ structure is long or prismatic with fibrous aggregates. The texture of the material is generally harsh, but can sometimes be soft. The material possesses a poor level of flexibility and spinnability, but does show a strong resistance to heat, acids and alkalies.
Modern Uses
Although recent attempts are routinely made to decrease the friability (crumbliness) of asbestos-containing products, this process cannot guarantee exposure will not occur. Large quantities of material and construction containing these minerals were produced prior to asbestos regulations and bans. As these materials are still in existence they can present a serious health hazard. Products containing the various forms of asbestos include asbestos-cement, brake shoes and pads, plastics, roof sealants, and road asphalt, as well as other applications. Despite the industry’s attempts to stabilize the mineral, health professionals and scientists agree that there is not a safe level of exposure to this material, as it acts as a human carcinogen. Despite the known health risks, countries involved in the production and mining of asbestos have gone as far as attempting to block the toxic mineral’s classification as such.
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