A common form of magnesium silicate and naturally occurring mineral fiber that was used in various construction products and older homes because of its stability and resistance to fire. Asbestos is also the name given to certain inorganic minerals in their fibrous form. Although asbestos is fire-resistant, it is considered a serious health hazard because its extremely fine fibers are easily inhaled, and exposure to these fibers over a long period of time has been linked to cancers of the lung and the lung-cavity lining, as well as asbestosis, which is a severe lung impairment. Homeowners should be alert for the existence of friable asbestos (that which is readily crumbled or brittle) and always seek professional advice before disturbing it.
|Formula mass||277.11 g|
|Color||Green, red, yellow, white, blue|
|Crystal habit||Amorphous, granular, massive|
|Mohs scale hardness||2.5–3|
|2V angle||20° to 60°|
Asbestos is a set of six naturally occurring silicate minerals, which all have in common their eponymous asbestiform habit: i.e. long (roughly 1:20 aspect ratio), thin fibrous crystals, with each visible fiber composed of millions of microscopic "fibrils" that can be released by abrasion and other processes. They are commonly known by their colors, as blue asbestos, brown asbestos, white asbestos, and green asbestos.
Asbestos mining existed more than 4,000 years ago, but large-scale mining began at the end of the 19th century, when manufacturers and builders began using asbestos for its desirable physical properties. Some of those properties are sound absorption, average tensile strength, affordability, and resistance to fire, heat, and electricity. It was used in such applications as electrical insulation for hotplate wiring and in building insulation. When asbestos is used for its resistance to fire or heat, the fibers are often mixed with cement or woven into fabric or mats. These desirable properties made asbestos very widely used. Asbestos use continued to grow through most of the 20th century until public knowledge (acting through courts and legislatures) of the health hazards of asbestos dust outlawed asbestos in mainstream construction and fireproofing in most countries.
Inhalation of asbestos fibers can cause serious and fatal illnesses including lung cancer, mesothelioma, and asbestosis (a type of pneumoconiosis). Concern of asbestos-related illness in modern times began with the 20th century and escalated during the 1920s and 1930s. By the 1980s and 1990s, asbestos trade and use were heavily restricted, phased out, or banned outright in an increasing number of countries.
Despite the severity of asbestos-related diseases, the material has extremely widespread use in many areas. Continuing long-term use of asbestos after harmful health effects were known or suspected, and the slow emergence of symptoms decades after exposure ceased, made asbestos litigation the longest, most expensive mass tort in U.S. history and a much lesser legal issue in most other countries involved. Asbestos-related liability also remains an ongoing concern for many manufacturers, insurers and reinsurers. On July 12, 2018, a Missouri jury ordered Johnson & Johnson to pay a record $4.69 billion to 22 women who alleged the company’s talc-based products, including its baby powder, contain asbestos and caused them to develop ovarian cancer.