Igneous rocks can be divided into four categories based on their chemical composition: felsic, intermediate, mafic, and ultramafic. The diagram of bowen’s reaction series (figure 7.6) shows that differences in chemical composition correspond to differences in the types of minerals within an igneous rock.
How to Classify Igneous Rocks?
Igneous rocks are an important part of the Earth’s structure and composition. They are formed when magma cools and solidifies, and can be found all over the Earth’s surface. Knowing how to classify igneous rocks is essential for geologists and other scientists to understand the Earth’s structure and composition.
The first step in classifying igneous rocks is to determine whether the rock is intrusive or extrusive. Intrusive rocks are formed when magma cools within the Earth’s crust. When this happens, the magma cools slowly and has a coarse-grained texture. Extrusive rocks, on the other hand, are formed when magma is expelled from the Earth’s surface, such as in a volcanic eruption. These rocks cool quickly and have a fine-grained texture.
Once the type of rock is determined, geologists must identify the rock’s mineral composition. Igneous rocks are made up of a variety of minerals, including quartz, feldspar, mica, and hornblende. By looking at a sample of the rock under a microscope, geologists can identify which minerals it contains.