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Biotite vs. Hornblende — What's the Difference?

Edited by Tayyaba Rehman — By Fiza Rafique — Updated on September 27, 2023
Biotite is a black mica mineral, while Hornblende is a dark amphibole mineral. Both are silicate minerals found in igneous and metamorphic rocks.
Biotite vs. Hornblende — What's the Difference?

Difference Between Biotite and Hornblende

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Key Differences

Biotite and Hornblende are two distinct minerals commonly found in various types of rocks. Biotite, belonging to the mica group of minerals, often appears in sheets or flakes and is primarily black to brown in color. Hornblende, on the other hand, is an amphibole mineral that typically exhibits elongated or prismatic crystals, with colors ranging from green-black to brown-black.
Fiza Rafique
Sep 27, 2023
Biotite can be identified by its characteristic shiny, layered appearance and is often part of the granite and other felsic rocks composition. Hornblende, contrasting Biotite, shows a vitreous to dull luster and is an essential constituent in many igneous rocks such as andesite and diorite, as well as in certain metamorphic rocks.
Fiza Rafique
Sep 27, 2023
Chemically, Biotite is a silicate containing iron, magnesium, aluminum, silicon, oxygen, and hydrogen. Hornblende, while also being a silicate, has a more complex chemistry and can contain calcium, sodium, magnesium, iron, aluminum, silicon, oxygen, and hydrogen. Thus, even at a chemical level, Biotite and Hornblende differ.
Fiza Rafique
Sep 27, 2023
The cleavage patterns in these minerals also serve as distinguishing features. Biotite displays a perfect basal cleavage, allowing it to be split into thin sheets. Hornblende has two cleavage directions, intersecting at roughly 60 and 120 degrees, making its cleavage less perfect than Biotite's.
Fiza Rafique
Sep 27, 2023
While Biotite and Hornblende are both widespread and significant in geological studies, they have unique properties and appearances that set them apart, facilitating differentiation by geologists and mineralogists.
Fiza Rafique
Sep 27, 2023
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Comparison Chart

Mineral Group

Mica Group
Amphibole Group
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Sep 27, 2023

Common Color

Black to brown
Green-black to brown-black
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Sep 27, 2023

Luster

Shiny
Vitreous to dull
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Sep 27, 2023

Cleavage

Perfect basal cleavage (sheets)
Two directions at roughly 60 and 120 degrees
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Sep 27, 2023

Typical Rock Presence

Granites and other felsic rocks
Igneous rocks like andesite and diorite; certain metamorphic
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Sep 27, 2023

Compare with Definitions

Biotite

A dark mica mineral composed of iron, magnesium, and aluminum silicates.
The rock sample contained flakes of Biotite.
Fiza Rafique
Sep 27, 2023

Hornblende

A mineral displaying two cleavage directions.
He noted the characteristic cleavage of Hornblende under magnification.
Fiza Rafique
Sep 27, 2023

Biotite

Recognized by its shiny, flaky appearance.
Biotite sheets shimmered when light fell on them.
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Sep 27, 2023

Hornblende

Known for its green-black to brown-black coloration.
The dark prismatic crystals in the andesite were Hornblende.
Fiza Rafique
Sep 27, 2023

Biotite

A black to brown phyllosilicate mineral.
Biotite lent the granite its characteristic dark specks.
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Sep 27, 2023

Hornblende

A complex silicate mineral of the amphibole group.
The dark, elongated crystals in the stone were identified as Hornblende.
Fiza Rafique
Sep 27, 2023

Biotite

A common silicate mineral found in various rocks, often in sheets.
He observed the layered structure of Biotite under the microscope.
Fiza Rafique
Sep 27, 2023

Hornblende

Commonly found in igneous and metamorphic rocks.
The presence of Hornblende gave the rock its dark hue.
Fiza Rafique
Sep 27, 2023

Biotite

A key constituent in many igneous and metamorphic rocks.
The geologist identified Biotite in the rock cross-section.
Fiza Rafique
Sep 27, 2023

Hornblende

Exhibits a vitreous to dull luster.
The Hornblende in the sample lacked the shininess of mica.
Fiza Rafique
Sep 27, 2023

Biotite

Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula K(Mg,Fe)3AlSi3O10(F,OH)2. It is primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more aluminous end-members include siderophyllite and eastonite.
Fiza Rafique
Apr 09, 2022

Hornblende

Hornblende is a complex inosilicate series of minerals (ferrohornblende – magnesiohornblende). It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole.
Fiza Rafique
Apr 09, 2022

Biotite

A dark-brown or dark-green to black mica, K(Mg,Fe)3(Al,Fe)Si3O10(OH)2, found in igneous and metamorphic rocks.
Fiza Rafique
Apr 09, 2022

Hornblende

The most common mineral in the amphibole group, CaNa(Mg,Fe)4(Al,Fe,Ti)3Si6O22(OH,F)2 commonly green to black, found in igneous and metamorphic rocks.
Fiza Rafique
Apr 09, 2022

Biotite

(mineral) A dark brown mica; it is a mixed aluminosilicate and fluoride of potassium, magnesium and iron.
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Apr 09, 2022

Hornblende

(mineral) A green to black amphibole mineral, of complex structure, formed in the late stages of cooling in igneous rock.
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Apr 09, 2022

Biotite

Mica containing iron and magnesia, generally of a black or dark green color; - a common constituent of crystalline rocks. See Mica.
Fiza Rafique
Apr 09, 2022

Hornblende

The common black, or dark green or brown, variety of amphibole. (See Amphibole.) It belongs to the aluminous division of the species, and is also characterized by its containing considerable iron. Also used as a general term to include the whole species.
Fiza Rafique
Apr 09, 2022

Biotite

Dark brown to black mica found in igneous and metamorphic rock
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Apr 09, 2022

Hornblende

A green to black mineral of the amphibole group; consists of silicates of calcium and sodium and magnesium and iron
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Apr 09, 2022

Common Curiosities

What is Biotite?

Biotite is a black to brown mica mineral commonly found in various rocks.
Fiza Rafique
Sep 27, 2023

Is Biotite a shiny mineral?

Yes, Biotite has a characteristic shiny appearance.
Fiza Rafique
Sep 27, 2023

How does Hornblende differ from Biotite in appearance?

Hornblende is typically green-black to brown-black and forms elongated crystals, while Biotite appears in sheets or flakes.
Fiza Rafique
Sep 27, 2023

Which rocks commonly contain Biotite?

Biotite is often found in granites and other felsic rocks.
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Sep 27, 2023

What's the typical color of Hornblende in rocks?

Hornblende usually has a green-black to brown-black coloration.
Fiza Rafique
Sep 27, 2023

Which mineral is more resistant to weathering, Biotite or Hornblende?

Hornblende is generally more resistant to chemical weathering than Biotite.
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Sep 27, 2023

Does Hornblende belong to the mica group like Biotite?

No, Hornblende belongs to the amphibole group.
Fiza Rafique
Sep 27, 2023

Can I find both Biotite and Hornblende in the same rock?

Yes, both can coexist in certain rock types like granodiorite.
Fiza Rafique
Sep 27, 2023

Do Biotite and Hornblende have the same chemical composition?

No, while both are silicates, they have different chemical constituents.
Fiza Rafique
Sep 27, 2023

What kind of rocks typically feature Hornblende?

Hornblende is common in igneous rocks like andesite and diorite, as well as some metamorphic rocks.
Fiza Rafique
Sep 27, 2023

Is Biotite found in metamorphic rocks?

Yes, Biotite can be present in various metamorphic rocks.
Fiza Rafique
Sep 27, 2023

How can I differentiate Biotite from other mica minerals?

Biotite is usually darker, typically black or brown, compared to other micas like muscovite which is often clear or silvery.
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Sep 27, 2023

Is Hornblende used commercially?

While not directly used, Hornblende's presence in rocks can influence the rock's overall properties and its commercial applications.
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Sep 27, 2023

Where can I typically find Biotite in everyday life?

Biotite is often visible as dark flakes in granite countertops or tiles.
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Sep 27, 2023

How is the cleavage of Hornblende different from that of Biotite?

Hornblende exhibits two cleavage directions, whereas Biotite has a perfect basal cleavage.
Fiza Rafique
Sep 27, 2023

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Author Spotlight

Written by
Fiza Rafique
Fiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
Tayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.

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