| Asbestos | |
|---|---|
 | |
| General | |
| Category | Silicate minerals |
| Strunz classification | 09.ED.15 |
| Dana classification | 71.01.02d.03 |
| Crystal system | Orthorhombic, monoclinic |
| Identification | |
| Formula mass | 277.11 g |
| Color | Green, red, yellow, white, gray, blue |
| Crystal habit | Amorphous, granular, massive |
| Cleavage | Prismatic |
| Fracture | Fibrous |
| Mohs scale hardness | 2.5.6.0 |
| Luster | Silky |
| Streak | White |
| Specific gravity | 2.4–3.3 |
| Optical properties | Biaxial |
| Refractive index | 1.53–1.72 |
| Birefringence | 0.008 |
| 2V angle | 20° to 60° |
| Dispersion | Relatively weak |
| Extinction | Parallel or oblique |
| Ultraviolet fluorescence | Non-fluorescent |
| Melting point | 400 to 1,040 °C (752 to 1,904 °F) |
Asbestos (/æsˈbɛstəs, æz-, -tɒs/ ass-BES-təs, az-, -toss)[1] is a naturally occurring, carcinogenic, fibrous silicate mineral. There are six types, all of which are composed of long and thin fibrous crystals, each fibre (particulate with length substantially greater than width)[2] being composed of many microscopic "fibrils" that can be released into the atmosphere by abrasion and other processes. Inhalation of asbestos fibres can lead to various dangerous lung conditions, including mesothelioma, asbestosis, and lung cancer. As a result of these health effects, asbestos is considered a serious health and safety hazard.[3]
Archaeological studies have found evidence of asbestos being used as far back as the Stone Age to strengthen ceramic pots,[4] but large-scale mining began at the end of the 19th century when manufacturers and builders began using asbestos for its desirable physical properties. Asbestos is an excellent thermal and electrical insulator, and is highly fire resistant, so for much of the 20th century, it was very commonly used around the world as a building material (particularly for its fire-retardant properties), until its adverse effects on human health were more widely recognized and acknowledged in the 1970s.[5][6] Many buildings constructed before the 1980s contain asbestos.[7]
The use of asbestos for construction and fireproofing has been made illegal in many countries.[3] Despite this, around 255,000 people are thought to die each year from diseases related to asbestos exposure.[8] In part, this is because many older buildings still contain asbestos; in addition, the consequences of exposure can take decades to arise. The latency period (from exposure until the diagnosis of negative health effects) is typically 20 years.[7][9] The most common diseases associated with chronic asbestos exposure are asbestosis (scarring of the lungs due to asbestos inhalation) and mesothelioma (a type of cancer).[10]
Many developing countries still support the use of asbestos as a building material, and mining of asbestos is ongoing, with the top producer, Russia, having an estimated production of 790,000 tonnes in 2020.[11]
- ^ "asbestos". Dictionary.com Unabridged (Online). n.d.
- ^ "Exposure and Disposition". Exposure and Disposition – Asbestos – NCBI Bookshelf. National Academies Press (US). 2006.
- ^ a b "What is asbestos?". British Lung Foundation. 28 September 2015. Archived from the original on 16 April 2020. Retrieved 26 May 2019.
- ^ Yildirim Dilek; Sally Newcomb (2003). Ophiolite Concept and the Evolution of Geological Thought. Geological Society of America. p. 449. ISBN 978-0-8137-2373-0.
- ^ Bureau of Naval Personnel, Basic Electricity. 1969: US Navy.
- ^ Kazan-Allen, Laurie (15 July 2019). "Chronology of Asbestos Bans and Restrictions". International Ban Asbestos Secretariat.
- ^ a b Kazan-Allen, Laurie (2 May 2002). "Asbestos: Properties, Uses and Problems". International Ban Asbestos Secretariat.
- ^ Furuya, Sugio; Chimed-Ochir, Odgerel; Takahashi, Ken; David, Annette; Takala, Jukka (May 2018). "Global Asbestos Disaster". International Journal of Environmental Research and Public Health. 15 (5): 1000. doi:10.3390/ijerph15051000. ISSN 1661-7827. PMC 5982039. PMID 29772681.
- ^ King, Anthony (25 June 2017). "Asbestos, explained". Royal Society of Chemistry.
- ^ Cite error: The named reference
:1was invoked but never defined (see the help page). - ^ Flanagan, Daniel M. (29 January 2021). "Mineral Commodity Summaries 2021". Mineral Commodity Summaries. U.S. Geological Survey. pp. 26–27. doi:10.3133/mcs2021. S2CID 242973747.