hornblende

American  

[hawrn-blend] / ˈhɔrnˌblɛnd /

noun

1. a dark-green to black mineral of the amphibole group, calcium magnesium iron and hydroxyl aluminosilicate.

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hornblende British  

/ ˈhɔːnˌblɛnd /

noun

1. a black or greenish-black mineral of the amphibole group, found in igneous and metamorphic rocks. Composition: calcium magnesium iron sodium aluminium aluminosilicate. General formula: (Ca,Na) 2.3 (Mg,Fe,Al) 5 Si 6 (Si,Al) 2 O 22 (OH) 2

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hornblende Scientific  

/ hôrn′blĕnd′ /

1. A common, green to black mineral of the amphibole group. It has a variable composition and occurs in monoclinic crystals with a hexagonal cross-section, in fibrous forms, or in granular forms. Hornblende is found in many metamorphic and igneous rocks. Chemical formula: (Ca,Na) _2-3 (Mg,Fe,Al) ₅ (Al,Si) ₈ O ₂₂ (OH) ₂₂ .

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Other Word Forms

• hornblendic
  adjective

Etymology

Origin of hornblende

From German, dating back to 1760–70; see origin at horn, blende

Example Sentences

Other minerals, with hornblende being a good example, are longer in one direction, linear like a pencil or a needle, rather than a planar-shaped book.

From Textbooks • Jan. 1, 2017

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

Linear crystals, such as hornblende, tourmaline, or stretched quartz grains, can be arranged as part of a foliation, a lineation, or foliation/lineation together.

From Textbooks • Jan. 1, 2017

Biotite and hornblende are also commonly used for K-Ar dating.

From Textbooks • Jan. 1, 2015

In the hand specimen many of the hornblende and biotite dacites are grey or pale brown and yellow rocks with white felspars, and black crystals of biotite and hornblende.

From Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 8 "Cube" to "Daguerre, Louis" by Various