Rocks are detrital. Description and classification of rocks

In the bowels of the earth is almost the entire periodic table. Chemical elements form compounds among themselves, of which natural minerals are composed. One or more minerals can enter the rocks of the earth. In this article, we will try to understand their diversity, properties and meaning.

What is a rock

For the first time this term was applied by our Russian scientist Severgin in 1978. Definition can be given this: rocks - this is a combination of several minerals of natural origin, having a constant structure and composition. Rocks can be found everywhere, as they are an integral part of the earth's crust.

If we study the description of rocks, then they all differ in the features:

• Density.
• Porosity.
• The color.
• Strength.
• Resistant to severe frost.
• Decorative qualities.

Depending on the combination of qualities, they find application.

Variety of rocks

The division of rocks into different types is based on chemical and mineral composition. The name of the rocks is given depending on their origin. Consider the groups they are divided into. A common classification can look like this.

1. Sedimentary rocks:

• Mountain rocks clastic;
• Organogenic;
• Chemogenic;
• Mixed.

2. Magmatic:

• Volcanic;
• Plutonic;
• Hypabyssal.

3. Metamorphic:

• Isochemical;
• Metasomatic;
• Ultrametamorphic.

Next, let us consider in more detail the characteristics of these rocks.

Sedimentary rocks

Any rocks, appearing under the sights of various factors and external processes, can deform, change their shape. They begin to collapse, fragments are carried, can be deposited at the bottom of the seas and oceans. As a result, sedimentary rocks form.

It is difficult to classify rocks of sedimentary origin, since most of them were formed under the influence of many processes, and therefore it is practically impossible to attribute them to a specific group. Currently, this type of breed is divided into:

• Detrital rocks. Examples can be given different: all familiar gravel or crushed stone, sand and clay, and many others.
• Organogenic.
• Chemogenic.

Let us dwell a little more on each species of rock.

Mountain rocks clastic

They appear as a result of the formation of debris. If to classify them taking into account their structure, then allocate:

• Concreted rocks.
• Uncemented.

The first variety in its composition has a connecting component, which can be represented by carbonates, clays. The second variety does not have such substances, therefore has a loose structure.

It can be further clarified that clastic rocks often include traces and remnants of plant and animal organisms. These include shells of mollusks, preserved petrified parts of the stem, wings of insects.

The most clastic rocks are known. Examples confirm this. Known clays include sand and clay, crushed stone and gravel, and many others. All of them are widely used in the construction industry.

Chemogenic rocks

This group is a product of chemical reactions. To attribute to them it is possible salts, for example potash, and bauxites. The process of formation of this type of rock can go in two ways:

1. Gradual process of concentration of solutions. The influence of radiation from the sun is not excluded here.
2. The combination of several salts at a lower temperature.

The structure of such rocks will depend on the place of their appearance. Those that are formed on the surface of the earth have the form of a formation, and the deep ones are completely different.

Very widely used from this group are rocks, examples only confirm this. The chemogenic rocks include:

• Mineral salts.
• Bauxite.
• Limestones.
• Dolomite and magnesite and many others.

In nature, quite often there are rocks, in the formation of which various natural processes took part. The name of the rocks that occurred in this way are mixed. For example, you can find sands with an admixture of clay.

Organic sedimentary rocks

If clastic rocks sometimes include in their composition the remains of living organisms, then this group consists only of them. It includes:

• Oil and shale.
• Bitumens.
• Phosphate rocks.
• Carbonate compounds, such as chalk, which they write on the school board.
• Limestones.

If we talk about the composition, the limestones and chalk almost entirely consist of the remains of shells of ancient mollusks, foraminifera, corals, and also include algae. Considering that different organisms can give rise to an organogenic breed, they are divided into several varieties:

• Bioherms. The so-called clusters of living organisms.
• Thanatocenoses and tafrocenoses are the remains of organisms that have long lived in these places or were brought by water.
• Planktonic rocks were formed from organisms inhabiting water bodies.

Sedimentation of sedimentary rocks

This feature is one of the characteristics of the structure of sedimentary rocks. If you look at the rocks, then they can be divided into homogeneous and with inclusions. In the first variant, the whole rock is perceived as a homogeneous mass, and in the second one it is possible to consider separate fractions, grains and their shape and ratio.

If we consider the size of the fractions, then we can distinguish several groups:

1. The grains are quite clearly visible.
2. Hidden-grained visually appear to be structureless.
3. In the third group it is impossible to consider the granularity without special equipment.

The form of inclusions can be one of the criteria by which these breeds are shared. There are several types of structures:

• Hypodiomorphic. In this type, the crystals obtained from the solution serve as grains.
• Hypidoblast type refers to an intermediate structure in which a redistribution of substances occurs in the already hardened rock.
• Granoblastic, or leaf, has crystals of irregular shape.
• The mechanoconform type is formed as a result of the mechanical action of grains under the pressure of those layers that are located above.
• Non-conformal grains have the main feature in the form of different grain shapes, which leads to the appearance of voids and porosity.

In addition to the structure, the texture is also highlighted. The basis of division is stratification:

• Gradation. Its formation is carried out at great depths under water.
• The interlayer occurs in some layers of water, this type includes clay primes, sand interlayers in clay.
• Overlapping occurs at a large thickness of the layer, it is possible to observe a change in the color gamut of the layers. An example is the alternation of clay and sand.

It is possible to give many more classifications, but this, perhaps, we will stop.

Representatives of sedimentary rocks

We have already considered sedimentary clastic rocks, examples have also resulted, but now we will focus on others, which are also widespread in nature.

1. Gravelstones. They represent sedimentary rocks in the form of gravel. They include fragments of rocks and minerals of various sizes.
2. Sandy rocks. These include sand and sandstone.
3. Dusty rocks are somewhat reminiscent of sandstones, only in their composition have more stable minerals in the form of quartz, muscovite.
4. Aleurolite is distinguished by the presence of roughness at the break, and the color depends on the cementitious material.
5. Loams.
6. Clay rock.
7. Argillites.
8. Mergels are a mixture of carbonates and clay.
9. Limestones, which consist of calcite.
10. A piece of chalk.
11. Dolomites resemble limestones, but instead of calcite, dolomite is included in their composition.

All these rocks are widely used in construction and other branches of the national economy.

Metamorphic rocks

If we recall what a metamorphosis is, it becomes clear that metamorphic rocks appear as a result of the transformation of minerals and rocks under the influence of temperature, light, pressure, and water. The most famous of this group are: marble, quartzite, gneiss, schists and some others.

Since metamorphosis can be subjected to different types of rocks, the classification also depends on this:

1. Metabasites are rocks that are obtained as a result of the transformation of magmatic and sedimentary rocks.
2. Metapelites are the result of the transformation of acidic sedimentary rocks.
3. Carbonate rocks, for example marble.

The form of the metamorphic rock is preserved from the previous one, for example, if the rock was formerly situated in layers, then the newly formed one will have the same shape. The chemical composition, of course, depends on the original rock, but under the influence of transformations it can change. The mineral composition can be different, and it can include both one mineral and several.

Rocky rocks

This group of rocks accounts for almost 60% of the entire earth's crust. They arise as a result of the melting of rocks in the mantle or in the lower part of the earth's crust. Magma is a molten substance, partially or completely, enriched with various gases. The process of formation is always associated with a high temperature in the earth's interior. The geological processes taking place inside the earth constantly provoke the magma to rise to the surface. During the process of cooling, the mineral cools and crystallizes. This is the process of formation of igneous rocks.

Depending on the depth at which the hardening takes place, the rocks are divided into several groups, the varieties table can look like this:

Plutonic	Volcanic	Hypabyssal
Such rocks are formed in the lower part of the earth's crust.	Formed during the eruption of magma on the surface.	The breed appears when magma fills cracks in already existing rocks.

Magmatic rocks differ from clastic rocks in that there are no remains of dead organisms in them. Granite rock is one of the most famous among this group. It includes: feldspar, quartz and mica.

When the eruption of the volcano occurs, the magma, coming to the surface of the earth, gradually cools and forms rocks of volcanic type. They do not contain large crystals, since the decrease in temperature occurs quickly enough. Representatives of such rocks are basalt and granite. They were often used in antiquity to make monuments and sculptures.

Clastic rocks are volcanogenic

In the process of volcanic eruptions, not only rock rock is formed, but many others. In addition to the outpouring of lava, a large amount of debris flies into the atmosphere, which, together with the clots of the hardening lava, fall to the surface of the earth and form tephra. This pyroclastic material is gradually blurred, some of it is destroyed by water, and the one that remains, thickens and turns into strong rocks - volcanic tuffs.

On the fault of these rocks, fragments can be seen, the intervals between which are filled with ash, sometimes clay or siliceous sediments.

Weathering of rocks

All rocks, being in nature, are exposed to many factors, as a result of which weathering or destruction occurs. Depending on the impact, several types of this process are distinguished:

1. Physical weathering of rocks. Occurs because of temperature changes, as a result of which rocks crack, water enters into these cracks, which can turn into ice at negative temperatures. So the destruction of the rock is gradually taking place.
2. Chemical weathering is carried out under the influence of water, which falls into the cracks of the rock and leaches it, dissolves it. This effect is most likely to be affected by marble, limestone, and salt.
3. Biological weathering is carried out with the participation of living organisms. For example, plants with their roots destroy the rock, lichens, settling on them, secrete some acids, which also act destructively.

It is almost impossible to avoid the process of weathering of rocks.

Value of rocks

It is impossible to imagine a national economy without the use of rocks. To implement such an application began in ancient times, when a man learned to process stones. First of all, rocks are used in the construction industry. Examples include the following:

• Marble.
• Limestone.
• A piece of chalk.
• Granite.
• Quartzite and others.

Their use in construction is based on strength and other important qualities.

Some rocks find their application in the metallurgical industry, for example refractory clay, limestone, dolomites. The chemical industry is inseparable from rock salt, trefoil, diatomite.

Even light industry uses rocks for their needs. In agriculture, you can not do without potassium salts, phosphorites, which are an important part of fertilizers.

Thus, we examined the rocks. And we can conclude that at present they are indisputable and necessary aids to people in virtually every industry, from everyday life to construction. That is why the notion of rock, rather than rock, is most often used, which is the mineral that exactly expresses the significance of these natural deposits.