The surface of our planet is full of rocks and variety of minerals. But, more specifically, 95% of the upper layer of the earth’s crust is made up of igneous rocks, also magmatic called. Some are well known, such as the Obsidian and the granite, but others, surely, do not know them.
You still don’t know them well and you are interested in learning about them? So, keep reading because in this ecology article we will see everything about the igneous rocks, their types, characteristics and several examples.
Characteristics of igneous rocks
The Magmatic rocks They form when the molten rock in the form of magma cools and the minerals that form are crystallized and intertwined their particles. Magma can cool on the surface, due to volcanic eruptions, or inside the lithosphere, which is the solid layer of the earth’s surface. The vast majority of these rocks They are formed under the earth’s crust.
Although igneous rocks form a very high percentage of the top of the earth’s crust, they are usually under a layer of metamorphic rocks and sedimentary rocks. They have great importance in geology, since their characteristics and composition help to understand the terrestrial mantle and its composition, as well as to read past tectonic events.
Classification of igneous rocks and their types
Magmatic rocks can be classified from various ways, although their most general classification divides them according to their origin.
Plutonic or intrusive igneous rocks
They have formed inside the lithosphere. There, the magma cools in a much slower process, so it gives rise to rocks with large sizes crystals, which can be easily observed. These rocks are transported to the surface by erosion processes or by tectonic deformations. Plutonic rocks receive their name from the plutons, which are the great magmatic intrusions from which they are formed. It should be said that the heart of the largest mountain chains is made up of intrusive rocks.
Volcanic or extrusive igneous rocks
They are formed when the magma is expelled to the surface and cools quickly. The vast majority of these rocks are created by the effect of volcanic eruptions, and as magma cooling is at high speed, the crystals that are created inside the rocks are much smaller, invisible to the human eye. In this type of rock, the formation of holes or holes left by gas bubbles that are formed in the solidification process is common.
In addition to these two major classifications, we also have the Philonian rocksthat are halfway between the plutonic and the volcanic ones, when a magma reef that is directed towards the surface is solidified halfway. The Magmatic rocks They can also be divided according to their texture and composition.
You can learn more about volcanic rocks: types and characteristics reading this other article.
Types of igneous rocks according to its texture
- Vitreous: They are volcanic rocks that are formed by being violently thrown into the atmosphere, where they cool at high speed.
- Afanitics: volcanic with microscopic crystals.
- Phaneritic: formed when large amounts of magma solidify very slowly and great depth.
- PORFIDICA: These rocks have large crystals in the center and other children near the outside, due to unequal cooling.
- Pyroclastic: Pyroclasts are formed in explosive volcanic eruptions. They have no crystals and are formed by rock fragments.
- Pegmatitic: Of very thick grain, these rocks are formed by crystals of more than a centimeter in diameter. They are formed when the magma has large amounts of water and volatile elements.
Types of igneous rocks according to its chemical composition
Igneous rocks can have different levels of light or dark silicates.
- Feli: They are formed by 70% silica, low density and light colors. The continental cortex is mainly formed by them, and contain approximately 10% of dark silicates.
- Andesitics: They contain at least 25% of dark silicates.
- MAFICS: They are very rich in dark silicates. They are of greater density and darker colors, and constitute the oceanic crust.
- Ultramaficas: With at least 90% of dark silicates, they are rare rocks to find on the planet’s surface.
Examples of igneous rocks
Finally, these are some singles Examples of igneous rocks:
- Granite is the most common plutonic rock.
- The basalt is a widely known volcanic rock.
- Obsidian, widely used by our first ancestors in prehistory, is an igneous rock of vitreous texture.
- The peridotita is one of the rare ultra -traffic rocks.
- The riolite, an extrusive igneous rock, is considered the volcanic equivalent of granite.
If you want to read more articles similar to Igneous rocks: types, characteristics and exampleswe recommend that you enter our category of other environment.
