Igneous Rock : Description, Questions and Answers.

Hello, do you know Igneous rock? In this article we will discuss about igneous rock. This article will show you descriptions, questions and answers about igneous rock. Happy reading.

Igneous Rock

Igneous rock is a type of rock that forms from the solidification of magma or lava. Magma is molten rock that is found beneath the Earth’s surface, while lava is molten rock that has erupted and solidified on the surface.

Igneous rocks are classified according to their mode of origin, texture, and mineral composition. They can be formed from solidification of magma below the earth surface (Plutonic) or from solidification of lava on the surface (Volcanic).

The texture of an igneous rock is determined by the rate at which the magma or lava cools and solidifies. If the magma or lava cools quickly, the resulting rock will have a small grain size and a glassy texture. This type of igneous rock is called a volcanic rock. Examples of volcanic rock include basalt, pumice and obsidian. If the magma or lava cools and solidifies slowly, the resulting rock will have a large grain size and a coarse texture. This type of igneous rock is called a plutonic rock. Examples of plutonic rocks include granite, gabbro, and diorite.

The mineral composition of an igneous rock is determined by the chemical makeup of the magma or lava from which it formed. Different types of magma and lava have different chemical compositions, which results in different mineral compositions in the resulting igneous rock.

There are several ways to classify igneous rocks based on their mineral composition, one of the most common is the TAS (Total Alkali Silica) classification, which separates rocks into 3 main categories: felsic, intermediate and mafic.

Felsic rocks have a high content of silica (SiO2) and are typically light-colored and rich in minerals such as quartz and feldspar. Examples of felsic rocks are granite and rhyolite.

Intermediate rocks have a moderate content of silica and are typically gray to dark-colored. They are rich in minerals such as plagioclase feldspar, hornblende and biotite. Examples of intermediate rocks are diorite and andesite.

Mafic rocks have a low content of silica and are typically dark-colored. They are rich in minerals such as olivine, pyroxene and biotite. Examples of mafic rocks are gabbro and basalt.

Igneous rocks can also be classified based on their texture and mineral composition, and can be further divided into more specific categories such as granite, diorite, gabbro, etc.

In conclusion, Igneous rocks are formed from the solidification of magma or lava and can be classified based on their mode of origin, texture and mineral composition. The characteristics of an igneous rock are determined by the rate at which the magma or lava cools and solidifies, as well as by the chemical composition of the magma or lava. These characteristics play a critical role in the geology of the Earth and are important in fields such as mining, oil and gas exploration, and civil engineering.

Questions and Answers About Igneous Rock

1. Which type of rock is formed from the solidification of magma or lava?

Answer :

Igneous rock is a type of rock that forms from the solidification of magma or lava. Magma is molten rock that is found beneath the Earth’s surface, while lava is molten rock that has erupted and solidified on the surface.

When magma or lava cools and solidifies, the process is called solidification. During solidification, the atoms and molecules in the molten rock begin to slow down and eventually come to a stop, forming a solid mass. The rate at which the magma or lava cools and solidifies can have a significant impact on the characteristics of the resulting igneous rock.

If the magma or lava cools and solidifies quickly, the resulting rock will have a small grain size and a glassy texture. This type of igneous rock is called a volcanic rock. Examples of volcanic rock include basalt, pumice and obsidian.

If the magma or lava cools and solidifies slowly, the resulting rock will have a large grain size and a coarse texture. This type of igneous rock is called a plutonic rock. Examples of plutonic rocks include granite, gabbro, and diorite.

Igneous rock can also be classified based on its mineral composition, such as felsic, intermediate, mafic and ultramafic.

In conclusion, Igneous rock is a type of rock that forms from the solidification of magma or lava. The rate of solidification and the mineral composition determine the characteristics and the classification of the rock.

2. Where is magma located?

Answer :

Magma is molten rock that is found beneath the Earth’s surface. It is typically located in the Earth’s crust and upper mantle, within the lithosphere. The lithosphere is the solid outer layer of the Earth that includes the crust and the uppermost part of the mantle. Magma is found in areas where the Earth’s crust is thin or where there are weaknesses or cracks in the crust, such as at plate boundaries or near active volcanoes.

Magma can also be found in deeper parts of the Earth’s interior, in the asthenosphere and the lower mantle, where it is under much higher pressure and temperature. The molten rock in these deeper regions is called ‘magma’ only when it is intruded, that is, when it rises and solidifies in the upper layers of the Earth, otherwise it’s called ‘melt’.

In summary, Magma is molten rock that is typically located in the Earth’s crust and upper mantle, within the lithosphere and can be found in areas where the Earth’s crust is thin or where there are weaknesses or cracks in the crust, such as at plate boundaries or near active volcanoes and also can be found in deeper parts of the Earth’s interior.

3. Where is lava located?

Answer :

Lava is molten rock that has erupted and solidified on the surface of the Earth. It is typically located in areas where there is volcanic activity, such as near active volcanoes, volcanic islands, and volcanic rift zones. Volcanoes are found at plate boundaries, where tectonic plates are diverging or converging, and also in hot spots, where magma from the mantle rises to the surface.

When a volcano erupts, magma and ash are expelled from the vent and can flow out as a liquid or solidify as it cools. Lava can also be formed from volcanic fragments that have been thrown out of the volcano and then solidify as they cool.

Lava can also be found on other planetary bodies in our solar system such as on Mars, Venus and Io, as well as on some of the moons around Jupiter and Saturn.

In summary, Lava is molten rock that has erupted and solidified on the surface of the Earth, typically located in areas where there is volcanic activity, such as near active volcanoes, volcanic islands, and volcanic rift zones and also can be found on other planetary bodies in our solar system such as on Mars, Venus and Io, as well as on some of the moons around Jupiter and Saturn.

4. Describe the texture of the following igneous rock (grain size 1-10 mm).

Answer :

The grain size of an igneous rock refers to the size of the crystals that make up the rock. The crystals form as the magma or lava cools and solidifies, and their size is determined by the rate of cooling. If the magma or lava cools quickly, the crystals will be small and the rock will have a fine-grained texture. If the magma or lava cools slowly, the crystals will be large and the rock will have a coarse-grained texture.

A medium-grained texture would indicate that the magma or lava cooled at a moderate rate, allowing for the formation of crystals that are larger than those in a fine-grained rock, but smaller than those in a coarse-grained rock. This size range (1-10 mm) is intermediate between fine and coarse grained.

It should be noted that the grain size is not the only feature that determines the texture of an igneous rock and the term “texture” in geology is a much broader concept, encompassing other aspects such as the shape and arrangement of crystals, the presence of vesicles, or the overall appearance of the rock.

5. Describe the texture of the following igneous rock (grain size < 1mm).

Answer :

An igneous rock with a grain size of less than 1mm would have a fine-grained texture.

The grain size of an igneous rock refers to the size of the crystals that make up the rock. The crystals form as the magma or lava cools and solidifies, and their size is determined by the rate of cooling. If the magma or lava cools quickly, the crystals will be small, forming a rock with a fine-grained texture. If the magma or lava cools slowly, the crystals will be large, forming a rock with a coarse-grained texture.

A fine-grained texture is characterized by small crystals that are not visible to the naked eye. This can happen because the magma or lava cools quickly, which doesn’t allow enough time for large crystals to form. This texture is also typical of volcanic rocks, as they cool rapidly upon contact with air or water. Examples of fine-grained igneous rocks include basalt, andesite and rhyolite.

It should be noted that the grain size is not the only feature that determines the texture of an igneous rock and the term “texture” in geology is a much broader concept, encompassing other aspects such as the shape and arrangement of crystals, the presence of vesicles, or the overall appearance of the rock.

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