Widely used in manufacturing and industry in the 20th century, members of the asbestos family of fibrous minerals are implicated in various diseases including an aggressive form of cancer, mesothelioma, firmly linked to exposure. This naturally occurring group of minerals consists of six members divided into two categories. Serpentine asbestos has curled fibers in contrast to the straight, narrow fibers of amphibole asbestos minerals. Members of the amphibole group constitute the most dangerous type of asbestos due to the needle-like fibers that become lodged in the tissues of the body.
Crocidolite asbestos, called blue asbestos due to its coloration, is no longer mined and played a relatively minor role in asbestos use in the United States. Its heat resistant properties are inferior to other forms and it was mainly used in the manufacture 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.
Brown asbestos, amosite, is another of the amphibole group. It is the second most dangerous of the asbestos minerals due to the long, straight fibers that the body cannot expel. Like blue asbestos, this variety has caused the death and illness of vast numbers of miners in South Africa. This form of asbestos made up about 5% of all industrially-used asbestos. Although it has been banned in many countries, amosite products are still in existence in buildings and can pose a hazard when fibers become airborne.
The most frequently used form of asbestos is chrysotile, a member of the curly-fibered serpentine group. This is the only commerically-used form of asbestos that belongs to this group. Its fibers are usually softer and less harsh than amphibole varieties, making it well suited for other uses. With a long history of use spanning over two centuries, chrysotile was first used for its heat resistant properties in textiles and lamp wicks. Mined in Canada, Russia, Italy and elsewhere, this mineral remains at the center of much debate concerning safety.
This greenish form of asbestos is commonly found in metamorphic rocks. Its structure is reticulated long prismatic crystals and fibers and it possesses a silky luster. Actinolite has a harsh texture and poor spinnability capabilities, meaning it was not likely made into a cloth, as other forms of asbestos were. Furthermore, this form of asbestos possesses a poor level of flexibility, while details on its resistance to heat are not available. The mineral impurities of this form of asbestos include lime and iron.
This form of asbestos, which ranges in color from grayish white to brown-gray or green, has a lamellar or fibrous structure. This amphibole material’s name is derived from the Latin word anthophyllum, which means clove, which is in reference to the most common color the mineral is found in. The luster of anthophyllite is vitreous to pearly and it possesses short fibers and a harsh texture. Although the material has a spinnability and flexibility, the material’s resistance to acids, alkalies and heat are very strong, making it a natural insulator.
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, though it is sometimes soft. The material possesses a poor level of flexibility and spinnability, though it does show good resistance to heat, acids and alkalies.
Modern Asbestos Use
Although recent attempts are routinely made to decrease the friability (crumbliness) of this mineral’s products, large quantities of material put in place before asbestos warnings and bans are still in existence and present a serious health hazard. These were primarily used to produce asbestos-cement but also used in brake shoes and pads, plastics, roof sealants, and road asphalt. Despite the industry’s attempts to stabilize the mineral, health professionals agree that there is no safe level of exposure to this carcinogenic material. Producing countries have even blocked attempts to have it classified as a toxic substance.