amphibole

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amphibole

(ăm`fəbōl'), any of a group of widely distributed rock-forming minerals, magnesium-iron silicates, often with traces of calcium, aluminum, sodium, titanium, and other elements. The amphibole minerals are closely related in crystal structure, but they crystallize in two different systems, orthorhombic and monoclinic; their close structural relationship is reflected in uniform prism angles of about 56° and 124° and in good cleavages parallel to these prisms. They are commonly green to black, but may be colorless, white, yellow, blue, or brown. The amphibole minerals are found both in igneous and metamorphic rocks. The commonest form is hornblende; other species include anthophyllite, cummingtonite, tremolite, actinolite, riebeckite, and glaucophane. A variety of jade, called nephrite, consists of actinolite in a finely fibrous form.
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amphibole

[′am·fə‚bōl]
(mineralogy)
Any of a group of rock-forming, ferromagnesian silicate minerals commonly found in igneous and metamorphic rocks; includes hornblende, anthophyllite, tremolite, and actinolite (asbestos minerals).
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Toxicological Review of Libby Amphibole Asbestos: In Support of Summary Information on the Integrated Risk Information System (IRIS), December 2014.
A general population cohort that has been environmentally and occupationally exposed to amphibole asbestos is currently being followed to further examine the temporal relationship between autoantibodies and lung disease [63].
Since the majority of the homes had VAI insulation containing amphibole asbestos, it is very likely that the insulation was derived from the Libby, Montana, Zonolite Mine.
In particular, even though the content of many materials that contain asbestos is predominantly chrysotile, such materials often contain small quantities of amphibole asbestos impurities and even intentionally added amphiboles.
In addition to the vermiculite product, the exfoliation produced a waste material that contained up to 10% amphibole asbestos [Minnesota Department of Health (MDH) 2005].
The median amphibole asbestos fiber counts for all subjects irrespective of fibrosis were 16 million fibers per gram of dry lung tissue for a naval dockyard cohort and 106 million fibers per gram of dry lung tissue for an asbestos product factory cohort (19,20); their respective standardized mortality ratios were 84 (not elevated) and 210 (more than doubling of risk).
They concluded that, for lung cancer, there is some evidence of larger [K.sub.L] values from amphibole asbestos exposure, although there was considerable dispersion in the data.
We evaluated the effect of XRCC1 knockdown on genotoxicity using noncarcinogenic fibers (wollastonite) and particles [titanium dioxide (Ti[O.sub.2])] and two types of amphibole asbestos, International Union Against Cancer (UICC) crocidolite and Libby amphibole.
The processing, use, and transport of the ore, which was contaminated with amphibole asbestos, led to generalized contamination of the community.
The vermiculite ore contained amphibole asbestos. Libby amphibole asbestos was determined to be composed of tremolite, winchite, and richterite (Meeker et al.
The Chrysotile Institute, a nonprofit organization funded by the Canadian government, maintains that chrysotile is not as toxic as amphibole asbestos. Institute president Clement Godbout says the high rates of respiratory disease and cancer associated with asbestos stem from exposure to the amphibole form and to high exposures from dangerous past practices such as blowing asbestos mixtures onto walls for insulation and fireproofing.