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

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

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

Diorite is identifiable by it’s Dalmatian-like appearance of black hornblende and biotite and white plagioclase feldspar.

From Textbooks • Jan. 1, 2017

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

From Textbooks • Jan. 1, 2015

Mica, iron oxides, apatite, zircon, epidote and hornblende may also be present in small amount.

From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" by Various