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Igneous rocks are formed based on several factors that start when the temperature increases around 10° for every kilometer below the surface of the Earth and in the Astinosphere region (extending from the depth of 2136 – (How much crust) The temperature becomes sufficient for large masses of magma to form. While the temperature of the magma varies from 2136- degrees Celsius depending on the chemical composition of the magma and its depth. When rocks melt and turn into magma, their volume increases by 100%, and thus its density becomes Below the surrounding rocks and then trying to climb to the top. As the magma rises upward, the pressure and temperature begin to decrease and the magma begins to solidify to form igneous rocks.
Classification of igneous rocks according to the place of their solidification
There are three main types of igneous rocks, based on the place of their hardening in nature:
1- Intrusive Igneous rocks
which consists of As a result of the hardening of the magma before it reaches the surface of the earth’s crust, this type of rock is also called “plutonic rocks” in relation to Pluto, “the god of spirits among the Romans” and is characterized by a coarse-grained texture where the cooling is slow, such as granite rocks.
2- Extrusive igneous rocks
They are formed as a result of the solidification of magma after reaching the surface of the earth’s crust. These rocks are sometimes called “volcanic rocks” in relation to Vulcan, “the god of fire for the Romans.” These rocks are distinguished by soft texture and the crystals are small in size, and examples are basalt and rhyolite rocks.
3- Subsurface volcanic rocks
It includes rocks that crystallize under the surface of the earth where The cooling is medium and its crystals are of medium size, like dolerite rocks.
A- Acidic rocks:
They are also called felsic or sialic rocks because they contain aluminum silicate, and they include igneous rocks in which the proportion of silica exceeds 42 % It is characterized by the minerals quartz and feldspar and its light colors, examples of which are granite and rhyolite.
B- Medium rocks:
The percentage of silica in these rocks decreases, as it ranges between -66 It is characterized by its medium colors between dark black and light white, such as diorite and andesite rock. C- Basal rocks: They are called “mafic rocks” because they contain large amounts of iron and magnesium, and the percentage of silica in them ranges between -52 % It is distinguished by its dark color, such as gabbro and basalt rocks.
D – suprabasal rocks:
The percentage of silica in these rocks does not exceed % It contains a high percentage of iron and magnesium and is characterized by its dark black color, and an example is the peridotite rock.
General Characteristics of Igneous Rocks
2136 (They are found in the form of blocks that have different shapes, since the origin is magma, which is formed when it cools, depending on the space it occupies.)
it consists of crystallized minerals, so Available in a variety of different colors.
It often contains mineral ores that differ according to the type of accompanying rocks.
It has no fossils. 2136
Block shapes Firearms
The dam:
It is formed by the interference of magma when it is parallel to the surfaces of Layers. 2136 2136
Cutter: It arises from the interference of magma fluid in the form of vertical plates that cut across the surfaces of the layers.
Annular incisors:
They are circular incisors inclined outward Single center.
The deep blocks (patholiths):
which are the most massive igneous masses Where the roots of mountain chains grow with no bottom and appear on the surface as a result of lifting and erosion processes, and they are often composed of granite and granodiorite. Acholiths:Pyroclastic masses consisting of a vertical support surmounted by a double convex part.
