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.

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).
References in periodicals archive ?
Crocidolite asbestos contains up to 27% iron by weight (Timbrell 1970), whereas Libby amphibole contains approximately 5% iron by weight (Meeker et al.
Autoantibodies from mice exposed lo Libby amphibole asbestos bind SSA/ Ro52-enriched apoptotic blebs of murine macrophages.
The eastern dyke is alkalic, and contains pseudomorphs of olivine phenocrysts in a fine-grained groundmass of plagioclase, brown amphibole, and pyroxene.
1992, Possible role of amphibole in the origin of andesite: some experimental and natural evidence: Contributions to Mineralogy and Petrology, v.
In fact, the 25 fiber-year value probably only applies to amphibole exposure, and the value for chrysotile exposure is considerably higher, on the order of 200 fiber-years.
Chrysotile is often confused with amphibole fibres creating a climate of fear around products which present no measurable risk to health.
Although somewhat similar in appearance, the 391 Ma amphibole cooling age from Green Island indicates that the lit-par-lit granite sheets in the metamorphic rocks on Green Island and in the Arichat metamorphic belt are older, and not related to the ca.
In a fresh unaltered rock it is possible successfully to analyse samples composed of, for example, only two or three biotite mica and/or amphibole crystals.
1974), "Analysis of the Amphibole Asbestiform Fibers in Municipal Water Supplies," Environ.
The Center for Asbestos Related Disease (CARD) is the primary local and national resource for responding to issues related to amphibole asbestos, providing health care, outreach, and research.
The five other types of asbestos are in the Amphibole group.