rocks Formations that contain a group of minerals found in nature, and are an essential part of the composition of the earth’s crust, and therefore the rock has a distinctive feature that separates it from another rock and makes it a self-contained unit.^[1][2][3] The rock is the basic unit in building the earth, while the mineral is the unit of the rock itself. Rocks differ from each other in terms of the types of constituent minerals and the relationship of these minerals to each other in the same rock.

The rocks are sands that were deposited and matched with each other, and after several years this formation of rocks was formed. For each type of rock, there are mud rocks that were deposited by rain water, while sedimentary rocks were formed by water waves, and finally igneous rocks that were formed from lava thrown by volcanoes. .

be rocks It is a geological process that takes long periods of time and occurs through multiple stages.

rock sections[عدل]

Rocks are divided according to their origin into three main sections:

igneous rocks[عدل]

Igneous rocks are formed from volcanic lava and are divided into two main classes: plutonic and igneous rocks. Plutonian or intrusive rocks arise after the lava cools and crystallizes slowly in the earth’s crust, while volcanic or extrusive rocks arise from lava that reaches the surface, either as a calf or as fragmented projectiles. Plutonian igneous rocks usually take a few thousand years to cool down, while volcanic igneous rocks only take a few days or weeks to cool down and solidify, such as: granite and ((lamal))

sedimentary rocks[عدل]

Sedimentary rocks are distinguished from igneous rocks in that they arise above the surface of the lithosphere as a result of the influence of visible factors (erosion factors) and the action of organic organisms.

Sedimentary rocks are formed by the deposition of clastic materials, organic matter, evaporites, and sands that are transported by wind or water and deposited in layers. This is followed by a process of natural cohesion between the granules and molecular materials during the formation period. Layers are formed on top of each other, layers of different thicknesses and different compositions, some of which contain many organic materials and others that contain many minerals. Thus, it becomes a book that can be read, analyzed, and deduced from the climate changes that accompanied the formation of the layers. Sedimentary rocks are formed all over the earth, and they can be analyzed and studied from top to bottom so that we know how the conditions of their formation were in the present (upper layers) and in the old (lower layers). The best sedimentary layers are those that originated at the bottom of the seas, where they settle away from wind factors that may transport parts of them from one place to another.

Among those layers are sandstone and limestone. The limestone is characterized by the fact that it consists of small shells under the water, so if the sea floor rose due to tectonic displacements to the top and land appeared on the ground, then it becomes mountains of limestone and becomes part of the features of the terrain. This is what happened, for example, to North Africa in the past, when those lands were under the sea, then the bottom of the White Sea, which was large in the past, rose, and North Africa appeared and the Mediterranean Sea, which we call the Mediterranean, was small.

Limestone is widespread in Egypt, for example, in the Giza and Helwan regions, and the Mokattam Mountain itself is made of limestone. The ancient Egyptians used to cut it from the surrounding mountains in the Giza and Helwan region, and built the pyramids from it. The matter differs with regard to the smaller pyramid of Giza, as King Menkaure wanted to cover it from the outside with granite rocks, which are harder than limestone. The ancient Egyptians transported granite stones from Aswan and the south of the valley to Giza and transported them by boat on the Nile. Granite is an igneous rock.

metamorphic rocks[عدل]

Metamorphic rocks are formed after exposure of any type of rock (including those previously formed metamorphic rocks) to different temperatures and pressures, and they are transformed from the original rocks that formed them. And these temperatures and pressures are higher than they are on the surface of the earth, so the original rocks change into other mineral rocks, and an example of this is the process of recrystallization), such as: schist and gneiss.

The transformation of a particular rock type into another that is described according to the geological model is called the rock cycle. The Earth’s crust (including the lithosphere) is full of metamorphic rocks. The percentage of rock distribution in the earth’s crust is estimated as follows: 95% igneous rocks, 4% clay rocks, 0.7% sandy rocks, and 0.3% calcareous rocks.

rock type	rock properties	rock name
Subterranean fireworks	Large mineral crystals of quartz, feldspar, hornblende, and mica. The color of the rock is usually light A large crystal of feldspar, hornblende, mica, and smaller quantities of quartz than granite, and its color is medium. Large mineral crystals of feldspar, hornblende, augite, olivine, mica, no quartz, dark color.	granite diorite gabbro
superficial fireworks	Small mineral crystals of quartz, feldspar, hornblende, and mica. The color of the rock is usually light. Small crystals of the minerals feldspar, hornblende, mica, and lesser amounts of quartz than rhyolite, medium in color. Small mineral crystal of feldspar, hornblende, augite, olivine, mica and no quartz, dark in colour, with possible bubbles. Glassy texture, no grains visible, volcanic, conchoidal, usually black in color, visible red-reddish-brown or black with white spots. Foamy texture, floats, usually light in colour.	rhyolite andesite basalt; obsidian Biomis
Chemical and biochemical sedimentary	The main mineral is calcite, and it usually occurs in seas, lakes, rivers, and caves. It often contains fossils, and it reacts easily with dilute HCI. In swamps and shallow water environments, it consists of cohesive layers of organic matter, mainly plant debris.	limestone coal
chemical sedimentary	It usually consists of salt deposits that result from the evaporation of sea water.	rock salt
mutant non-foliated (non-lamellar)	Calcite or dolomite crystals appear in it, and it results from the transformation of calcareous rocks. It consists mainly of the mineral talc, which is soft, and has a greasy or soapy texture. Very hard, cohesive granules coalesce into quartz crystals, turning from sandstone.	Nice steatite quartzite
metamorphosed fascia (lamellar)	It has clear foliations due to the presence of alternating bands of minerals of different colors. This rock usually results from the metamorphism of granite. Clear arrangement of flakes of minerals (flakes) such as mica. It is mainly caused by the transformation of cartilage and phyllite. Its appearance is shiny or silky, the surface of the rock appears wrinkled and results from the transformation of clays and slate. It produces crystals of calcite or dolomite, and results from the metamorphism of calcareous rocks.	Nice the schist phyllite slate

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  diorite stone

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  igneous volcanic rock

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  kimberlite

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  kimberlite 2

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  Olivine basalt

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  olivine

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  Graywake

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formation process[عدل]

There are three basic methods for the formation of rocks, and among the rocks common to all living organisms are certainly the ones that result from the deposition and accumulation of other materials on the surface of the earth, which is a deposition followed by a little transformation process, which is what happens with sand, chalk, rock salt (natural / halite) and peat coal (plant residues Uncharted black or dark brown in swamps and damp places).

And the fact that the coal was buried long ago (the time factor) and at a fairly deep depth (the pressure and temperature factor) makes it metamorphose to some extent. This is also what happens with many calcareous rocks, as those rocks may contain fossils if the degree of transformation is large, and this is due to the exposure of the material to a strong pressure or temperature, which results in a chemical reaction, so cooking or real cooking occurs, so we get metamorphic rocks.

Examples of this type of rock[عدل]

Schist (a metamorphic rock with a leafy structure that separates into thin layers) of clay and marble from limestone, when studying this transformation through more analytical means by conducting chemical analysis and through mineral sciences, we can link the transformation of their solid matter, the stage that follows the transformation is a process Fusion of these materials They often refer to these rocks as granite. There are also volcanic rocks, most of which are formed as a result of the fusion of rocks deep in the ground, the sum of these rocks formed under the influence of high heat without or through the occurrence of fusion of what is called igneous rocks (rocks formed by the solidification of magma (magma or lava) melted submerged), of course ignoring The nature of these classifications, there are many types that exist among these large classifications, and there are all kinds of sandstones (a sedimentary rock fused consisting of grains of sand and other minerals) that mediate between the sands of desert dunes and quartz rocks that are sometimes used in pavements where sand particles cannot be distinguished. And some. Of course, the cycle of rock transformation closes, for example, when there is granite exposed to the climate and the biological atmosphere, which are engines for the erosion of these rocks and their transformation into sediment.

However, one must be careful, as this logic related to the transformation of rocks into one another cannot be generalized, as it only generalizes on rocks and not on the rocks of continents, so something completely different from the melting of volcanic rocks results, and this was addressed in the previous question a year or two ago.

In general, there is what is called the earth’s interior, which is solid as flexible and merges through a large slow movement (moving 1 cm per year), transporting in its movement hot rocks to the surface of the globe, and at the surface the pressure decreases, and the rocks begin to melt at a distance Less than 100 km below the earth’s surface, the liquid that forms at these very rare areas is called a basalt magma. When magma reaches the surface where it is less dense, it is either a volcano or a mid-ocean fissure.

See also[عدل]

• Gravel
• marble
• Briquette
• igneous rock
• smooth stone
• volcanic eruption
• rocky cycle
• porphyry
• mattress
• lead
• Igneous rock texture

Resources[عدل]

Arabic sources[عدل]

• Basics of Historical Geology Book – Muhammad Ahmad Heikal.
• Sedimentary rocks in the field book.
• Principles of Petrology book.
• Minerals under the microscope book.
• Arab geology book.
• Stratigraphy – Ramzi Khader Al-Nasser.

• Stratigraphy portal
• Earth Sciences Portal
• Gemology and Jewelry Portal
• Chemistry portal

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