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 ?
The presence of talc and associated amphiboles was more common in women than it was in men (odds ratio, 3.24; 95% CI, 1.65-6.35).
Magma ascent rates from amphibole breakdown: an experimental study applied to the 1980-1986 Mount St.
Partly transformed amphibole remnants (edenite-pargasite-actinolite; Mg# = 0.81-0.88), chlorite (Mg# = 0.82-0.87), calcite, and minor prehnite and pumpellyite are observed locally.
Sumas Mountain chrysotile induces greater lung fibrosis in Fischer 344 rats than Libby amphibole, El Dorado tremolite, and Ontario ferroactinolite.
Interstitial minerals are clinopyroxene, amphibole, phlogopite and ilmenite, together with Na-rich plagioclase overgrowths (Fig.
The classification of amphiboles is based on the composition of the standard amphibole formula [AB.sub.2] [sup.IV][C.sub.5][sup.IV][T.sub.8][[O.sub.2].sub.2] [(OH).sub.2].
The andesites of Noorabad ophiolite in hand specimen and thin section have phenocrysts of plagioclase in a groundmass of clinopyroxene and amphibole minerals.
Most recently, subjects exposed to the Libby, MT, amphibole were shown to have elevated frequency and titers of ANA compared to a reference population [20].
Whether the amphibole fibers from the mining operation constituted asbestos was a hotly disputed issue at trial.
There are six types of asbestos but the three main types are Chrysotile (white) which is a serpentine snake-like fibre, and the generally recognised more harmful types of Amosite (brown) and Crocidolite (blue) which are amphibole, needle-like fibres.
These two types are serpentine and amphibole. In the serpentine variety, the asbestos fibers are curly and flexible.