Types of rocks and their properties


Rocks are known as solid natural formations that consist of one or more minerals, and are an essential part of the earth’s crust. Rocks are divided according to the way they are formed into three main types: igneous rocks, metamorphic rocks, and sedimentary rocks, and each type of rock has unique characteristics by which it can be distinguished from the other two types.

igneous rocks

Igneous rocks are rocks that are formed as a result of the solidification of molten materials (magma), and solidification may occur in the ground, so the resulting rocks are called igneous rocks, and some of them solidify on the surface of the earth, so they are called igneous rocks as well as igneous rocks. Igneous rocks are classified according to the percentage of silica in them into the following types :

Acidic Igneous Rock: A rock with a silica content of more than 66%. Examples include:

Granite: is an igneous rock that forms at great depth in the earth, and it is often coarse-grained rock; That is, its mineral content can be distinguished with the naked eye, and sometimes it can be medium or fine-grained.

Granite is mainly composed of quartz, feldspar, and mica, and there are rocks equivalent to granite, but differing from it in the nature of texture, namely: rhyolite, obsidian, bastion stone, and pumice, which is known as pumice stone.

Granodiorite: A coarse-grained igneous rock, the igneous counterpart of granodiorite is called dacite.

Intermediate Igneous Rocks: Igneous rocks have a silica content of 52-66%. Examples include:

Syenite: An underground rock, often coarse-grained, the volcanic counterpart of syenite is trachyte.

Diorite: An igneous rock with a volcanic isotope called andesite.

Primary igneous rocks: igneous rocks with a silica content ranging between 40-52% and include plutonic gabbro rocks, and their volcanic equivalent, basalt.

Above Base Igneous Rocks: Igneous rocks contain less than 40% silica. Examples include: donuts and peridotite.

igneous rock properties

Relatively strong rocks due to the cohesion of the grains that make up them during cooling.

Its main colors are black, white and gray, and there may be igneous rocks of dull colors.

It has a crystalline consistency as a result of its exposure to melting and cooling.

It does not contain fossils because it was exposed to a high temperature that does not allow any kind of life to exist in it.

They are not arranged in the form of layers, with the exception of volcanic ash rocks, which may form in the form of layers when deposited within water bodies.


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