Granite, an igneous rock, is felsic in nature.
In this article, we are going to discuss why granite is considered felsic not mafic.
Is Granite Felsic or Mafic? (Explained)
Granite is a light-colored rock, also known as plutonic rock.
The formation of granite is not by the eruption of the volcano but instead by forcing, cooling down lava inside the rocks under the earth’s crust, and after that, the magma solidifies inside the rock, making it igneous.
Granite contains those minerals that are in silicates, such as feldspar and quartz.
The composition of granite is mainly SiO2, containing a small number of other minerals that are considered impurities, such as Al2O3, CaO, MgO, and Fe2O3.
The high amount of silicates present in granite makes it an acidic rock.
This rock is hard and it does not crush or crack under pressure, which makes it capable of bearing heavyweights.
Due to its toughness, granite does not move from its place easily.
This property of granite, i.e. durability, makes it a perfect rock for use in constructional and decorative purposes.
We can see granite being used in the construction of roads, buildings, granite tiles, and other architectural works.
Felsic vs Mafic (What’s the Difference?)
Felsic and mafic are both igneous rocks which were formed after the solidification of melted lava.
When a volcano has erupted, its lava pushes itself into the ancient rocks present inside the earth’s surface.
When that lava is cooled down and becomes magma, the magma present in the rocks makes them igneous.
These two are different from each other because of their chemical composition.
Rocks that are rich in feldspar, quartz, and other minerals that contain mostly silica, and some other elements such as oxygen, sodium, and potassium are also found in abundance in these rocks.
Such rocks are considered felsic in nature.
Felsic lava is habitually discovered at 650-750˚ C and found under the earth’s crust.
Felsic rocks contain 70-80% of silica.
The abundance of silica is because it is commonly discovered in particular areas of the earth, known as convergent zones.
And the rocks that are rich in magnesium and ferric are considered mafic.
These rocks are mostly composed of heavy minerals and contain less silica, 45-55% in them.
Mafic lava is usually founded at 950˚ C and is founded at the diversion plate boundary.
Also, felsic rocks are light-colored, in whitish tones, while mafic rocks are dark-colored, such as greenish black or in blackish tone of colors.
The difference between felsic and mafic is due to the abundance or scarcity of silica.
There are rocks which contain 55-65% of silica.
These rocks are known as intermediate rocks because they fall in between felsic and mafic rocks.
How Do We Know Granite Is Felsic?
To test the surety of its nature, we will discuss the chemical and physical properties of granite and then match them with the properties of felsic and mafic substances.
Granite rock is mainly composed of quartz and feldspar stones.
These stones contain silica in abundance.
Granite also contains some dark minerals, but they are in the minority.
Secondly, granite is usually light pink, white or gray in color.
If we compare these chemical and physical properties of granite with felsic and mafic, we can say with confidence that granite is felsic, has a light color, and is rich in silica.
Does it matter if a substance is felsic or mafic?
In absolute means, it matters when it comes to chemical weathering.
What is chemical weathering?
Chemical weathering is a phenomenon that alters the molecular structure of rocks.
First and foremost, the rocks that are formed under high temperatures are more sensitive to chemical weathering than the rocks that are formed under slightly lower temperatures.
So, felsic rocks are formed under less temperature as compared to mafic rocks, hence felsic rocks are more durable than mafic rocks.
This factor proves the inertness of granite, being an ideal rock for architectural works.
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