The key difference between basalt and granite is that basalt is mostly occurring on ocean floors, while granite is in the crust of the earth in all continents.
Earth contains three kinds of rocks namely igneous rocks, sedimentary rocks, and metamorphic rocks. Basalt and granite are two types of igneous rocks. All rocks of igneous origin consist of magma or molten earth that finds its way up to the surface of the earth from fissures and cracks underneath the surface of the earth. The molten rocks that come out in the form of lava, upon cooling take the shape of igneous rocks. Two of the most famous igneous rocks, basalt and granite, have similarities causing confusion among people. However, there are many differences between basalt and granite that we are discussing in this article.
CONTENTS
1. Overview and Key Difference
2. What is Basalt
3. What is Granite
4. Side by Side Comparison – Basalt vs Granite in Tabular Form
5. Summary
What is Basalt?
Basalt is darker and consists of fine-grained minerals such as magnesium and iron. We can name basalt rocks as mafic rocks as well, just because of this property. Those who know the symbols of magnesium (Mg) and iron (Fe) will easily understand the logic behind the word mafic rocks.
When considering the nature of these rocks, basalt is basic in nature. Basalt forms when magma cools and solidifies on the surface of the earth. It mainly occurs on the floor of the ocean as magma solidifies quickly coming in contact with cool ocean water.
Figure 01: Appearance of Basalt
Basalt is an extrusive igneous rock; extrusive rocks are those that form from lava coming out of volcanoes. Cooling of intrusive rocks takes much longer than extrusive rocks. The basalt rocks split along columnar planes.
What is Granite?
Granite is lighter in complexion and has a coarse-grained texture. These rocks occur at depth, and we can see only when deep erosion takes place. Granite has a different composition as it mostly consists of feldspar and quartz, and hence, the name felsic rock. When considering the nature of these rocks, granite is acidic in nature. It occurs above the ocean and makes up much of continental crust.
Figure 02: Appearance of Granite
Granite is an intrusive ingenuous rock; rocks that form from magma that has yet not come out of the volcano are termed as intrusive rocks. Cooling of intrusive rocks takes much longer than extrusive rocks as they are under the surface of the earth. These rocks split along horizontal planes.
What is the Difference Between Basalt and Granite?
Of the two, basalt is darker and consists of fine-grained minerals such as magnesium and iron while granite is lighter and consist of feldspar and quartz. Among other differences, the nature of these rocks reveals that basalt is basic in nature, whereas granite is acidic in nature. Basalt forms when magma cools and solidifies on the surface of the earth. It mainly occurs on the floor of the ocean as magma solidifies quickly coming in contact with cool ocean water. On the other hand, granite occurs above the ocean and makes up much of continental crust. Basalt is an extrusive igneous rock, whereas granite is an intrusive ingenuous rock. One other difference between basalt and granite pertains to the way these two types of rocks split when putting under pressure. While basalt rocks split along columnar planes, granite rocks give way along horizontal planes. Obviously, this difference exists because of differences in the way the two types of rocks cool down.
Summary – Basalt vs Granite
Basalt and granite are two types of igneous rocks that we can find on earth. The key difference between basalt and granite is that basalt is mostly occurring on ocean floors, while granite is in the crust of the earth in all continents.
Reference:
1. “Basalt.” Wikipedia, Wikimedia Foundation, 13 Sept. 2018. Available here
2. “Granite.” Wikipedia, Wikimedia Foundation, 27 Sept. 2018. Available here
Image Courtesy:
1.”BasaltUSGOV”By Unknown – resourcescommittee.house.gov, Basalt_jpg.jpg, (Public Domain) via Commons Wikimedia
2.”ArideGranite1″By Etan J. Tal – Own work, (CC BY-SA 4.0) via Commons Wikimedia