Mafic vs. Felsic — What's the Difference?
Edited by Tayyaba Rehman — By Fiza Rafique — Updated on September 26, 2023
Mafic refers to igneous rocks rich in magnesium and iron, while Felsic refers to rocks rich in lighter elements like silicon and aluminum.
Difference Between Mafic and Felsic
Table of Contents
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Key Differences
Mafic rocks are primarily composed of minerals like olivine and pyroxene, which are rich in magnesium and iron. Felsic rocks, in contrast, predominantly contain minerals like quartz and feldspar, which are abundant in silicon and aluminum.
Mafic rocks are generally darker in color, due to the high content of iron and magnesium in their composition. Felsic rocks, with their high silica content, tend to be lighter in hue, ranging from pink to white.
Originating from the Earth's mantle, Mafic lavas are typically hotter and less viscous. Felsic lavas, however, which arise from continental crust, are cooler and tend to be more viscous.
One consequence of their different compositions is that Mafic rocks are denser than Felsic rocks. This is because of the heavier elements, magnesium and iron, present in Mafic rocks as compared to the lighter elements in Felsic rocks.
Comparison Chart
Composition
Rich in magnesium and iron.
Rich in silicon and aluminum.
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Color
Generally darker.
Generally lighter, like pink to white.
Origination
From the Earth's mantle.
From continental crust.
Viscosity
Less viscous lava.
More viscous lava.
Density
Denser rocks.
Less dense rocks.
Compare with Definitions
Mafic
Mafic refers to rocks rich in iron and magnesium.
Basalt is a common Mafic rock.
Felsic
Felsic refers to rocks rich in silicon and aluminum.
Granite is a classic example of a Felsic rock.
Mafic
Mafic rocks originate from the mantle.
The Mafic magma erupted from deep within the mantle.
Felsic
Felsic rocks are generally lighter in color.
The Felsic composition gives the rock its pinkish hue.
Mafic
Mafic lavas are usually hotter and less viscous.
The Mafic lava flowed smoothly across the landscape.
Felsic
Felsic indicates minerals like quartz and feldspar.
Quartz, a Felsic mineral, dominates this rock.
Mafic
Mafic rocks are typically darker in color.
The Mafic lava solidified into a dark-colored rock.
Felsic
Felsic lavas are cooler and more viscous.
The Felsic lava moved sluggishly due to its high viscosity.
Mafic
Mafic denotes minerals like olivine and pyroxene.
Mafic minerals are abundant in this rock sample.
Felsic
Felsic rocks arise from the continental crust.
The Felsic magma formed from melted continental crust.
Mafic
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite.
Felsic
In geology, felsic is an adjective describing igneous rocks that are relatively rich in elements that form feldspar and quartz. It is contrasted with mafic rocks, which are relatively richer in magnesium and iron.
Mafic
Relating to or containing a group of dark-colored silicate minerals, composed chiefly of magnesium and iron, that occur in igneous rocks, including hornblende, pyroxene, olivine, and biotite.
Felsic
Relating to or containing a group of light-colored silicate minerals that occur in igneous rocks, including minerals of the feldspathoid group and the minerals quartz, feldspar, and muscovite.
Mafic
(geology) Describing rocks, such as silicate minerals, magmas, and volcanic and intrusive igneous rocks, which contain relatively high concentrations of magnesium and iron.
Felsic
(mineralogy) Enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.
Mafic
A rock with such properties.
Felsic
A rock with such properties.
Common Curiosities
Which is typically hotter, Mafic or Felsic lava?
Mafic lava is generally hotter than Felsic lava.
What elements are common in Mafic rocks?
Mafic rocks are rich in magnesium and iron.
How do Felsic colors generally appear?
Felsic rocks tend to have lighter colors, like pink to white.
Are Mafic rocks denser than Felsic rocks?
Yes, Mafic rocks are denser due to their magnesium and iron content.
Where do Mafic rocks primarily originate from?
Mafic rocks primarily originate from the Earth's mantle.
Are Mafic rocks generally heavier or lighter in color?
Mafic rocks are generally darker in color.
Are basalt and gabbro examples of Mafic rocks?
Yes, both basalt and gabbro are examples of Mafic rocks.
Is granite a Mafic or Felsic rock?
Granite is a Felsic rock.
What are the primary minerals in Felsic rocks?
Felsic rocks primarily contain minerals like quartz and feldspar.
Why are Felsic rocks generally less dense?
Felsic rocks are less dense due to their high silicon and aluminum content.
Which type of rock, Mafic or Felsic, is typically more viscous when molten?
Felsic lava is typically more viscous than Mafic lava.
Do Mafic rocks generally have a higher melting point than Felsic rocks?
Yes, due to their composition, Mafic rocks generally have higher melting points than Felsic rocks.
Which has a higher silica content, Mafic or Felsic rocks?
Felsic rocks have a higher silica content than Mafic rocks.
Why are Mafic lavas less viscous?
Mafic lavas are less viscous due to their higher temperatures and lower silica content.
What's the primary difference in mineral composition between Mafic and Felsic rocks?
Mafic rocks are rich in olivine and pyroxene, while Felsic rocks contain more quartz and feldspar.
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Fiza RafiqueFiza 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.
Edited by
Tayyaba RehmanTayyaba 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.
