Types of Rocks and How They Are Formed

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Rocks can be hard to figure out, especially for nonscientists. It’s tempting to think all rocks are the same, just solid stationed objects spread across the Earth. But there are differences, and it gets interesting the more you uncover the different stories that make up different rock formations. Here’s a guide to help you understand the three types of rocks and how they form.

Igneous Rocks

Every rock has a special place in history, and for igneous rocks, we’re looking at formation processes dating back to over 4 billion years ago when the Earth was all magma. Generally, igneous rocks form as molten magma cools and crystallizes into the rock formation.

The molten magma can come from multiple sources, including partial melts of existing rocks in a planet’s mantle or crust. Furthermore, where the molten magma comes from can determine the type of igneous rocks that form in the process. For instance, intrusive rocks form below the Earth’s surface, creating huge crystals through slow cooling. And you may find diorite, granite, and pegmatite as examples of the slowly cooling intrusive rocks. On the other hand, extrusive rocks form outside the surface through eruption. The main difference between extrusive and intrusive rocks depends on the cooling rate after an eruption. Extrusive igneous rocks’ cooling takes place quickly, forming an amorphous glass.

Typical examples of igneous extrusive rocks are basalt, tuff, and pumice.

Generally, the formation process occurs through an increase in temperature, decrease in pressure, or a composition change. Geologists reveal that the formation can happen via either one or more of these three processes. Several ways exist to leverage igneous rocks for their mineral value. However, the only way for miners to extract the mineral value is to get the right tools, people, and partners. People like Howard Fensterman, with extensive knowledge in minerals coupled with his experience in litigation law, can help establish the grounds for your company to mine legally.

Sedimentary Rocks

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Sedimentary rocks also have an interesting story and take several thousand years to form.

However, they form quietly through the combination of sand, mud, and the remains of living things gathering on a sea bed or the floor. This process contrasts with igneous rocks, which form through loud, violent collisions and volcanic eruptions. The more sediment deposits build on top of each other, the heavier the sediments get, compressing each other to form the rock.

Therefore, the first way to identify a sedimentary rock is its layeredness. The layeredness occurs due to the constant depositions and cementation of different rock materials. The sedimentation process doesn’t form the individual particles coming together as different rock sediments. These particles form over time from natural activities like weathering and eroding away from the sedimentation process’s site. It takes the wind, water, ice, glaciers, and other agents of denudation to move these particles to where the sedimentation process takes place.

The sedimentation process can also occur from the precipitation of minerals or shells of aquatic creatures settling out of suspension. The slight differences in processes result in different types of sedimentary rocks. Chemical sedimentary rocks form as dissolving materials precipitate from the solution, creating typical minerals like limestone and iron ore. Organic sedimentary rocks form as plants and debris accumulate over time. Miners can get coal and some dolomite types from organic sedimentary rocks.

Metamorphic Rocks

Metamorphic rocks can best be classified by texture, chemical, and mineral formation processes. Generally, the metamorphic process forms by applying constant levels of heat and pressure to the sedimentary rocks. This process transforms the rocks along with their respective structures. Typical examples include marble, slate, and gneiss, making up a large part of the Earth’s crust.

All in all, rocks are distinguished mineral aggregates contributing to several construction and architectural projects worldwide. This guide can be helpful if you have a passion for understanding the different types of rocks and how they form.