amphibole

American  

[am-fuh-bohl] / ˈæm fəˌboʊl /

noun

Mineralogy.

1. any of a complex group of hydrous silicate minerals, containing chiefly calcium, magnesium, sodium, iron, and aluminum, and including hornblende, tremolite, asbestos, etc., occurring as important constituents of many rocks.

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amphibole British  

/ ˈæmfɪˌbəʊl /

noun

1. any of a large group of minerals consisting of the silicates of calcium, iron, magnesium, sodium, and aluminium, usually in the form of long slender dark-coloured crystals. Members of the group, including hornblende, actinolite, and tremolite, are common constituents of igneous rocks

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amphibole Scientific  

/ ăm′fə-bōl′ /

1. Any of a large group of usually dark minerals composed of a silicate joined to various metals, such as magnesium, iron, calcium or sodium. Amphiboles occur as columnar or fibrous prismatic crystals in igneous and metamorphic rocks. Most are monoclinic, but some are orthorhombic. Hornblende, actinolite and glaucophane are amphiboles. Chemical formula: (Mg,Fe,Ca,Na) _2-3 (Mg,Fe,Al) ₅ (Si,Al) ₈ O ₂₂ OH ₂ .

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Etymology

Origin of amphibole

1600–10; < French < Late Latin amphibolus amphibolous

Example Sentences

The most common amphibole, hornblende, is usually black; however, they come in a variety of colors depending on their chemical composition.

From Textbooks • Jan. 1, 2017

It usually contains roughly-equal amounts of light and dark minerals, including light grains of plagioclase feldspar and dark minerals like amphibole.

From Textbooks • Jan. 1, 2017

To be more specific, felsic rocks typically have biotite and/or amphibole; intermediate rocks have amphibole and, in some cases, pyroxene; and mafic rocks have pyroxene and, in some cases, olivine.

From Textbooks • Jan. 1, 2015

Figure 5.10 A granitic rock containing biotite and amphibole which have been altered near to the rock’s surface to limonite, which is a mixture of iron oxide minerals.

From Textbooks • Jan. 1, 2015

These lavas, destitute of amphibole and mica, are of a blackish brown, often varying to the deepest olive green.

From Personal Narrative of Travels to the Equinoctial Regions of America, During the Year 1799-1804 — Volume 1 by Ross, Thomasina