Rocks. Classification.

Education, consisting of minerals, and occurring in or on the earth's surface under certain geological conditions, are called “rock”. Formed they more than 4600 million years ago and have a different structure and colors.

In their origin, rocks are divided into three types: sedimentary, igneous and metamorphic.

The First group of minerals is formed on the surface of the crust of the Earth. Rocks of this type formed as a result of accumulation of sediments on land and in the water bodies and their subsequent sedimentation under the influence of gravity. Depending on the method of formation they are divided into:

• Chemical rocks. This group of minerals formed from aqueous solutions of nutrients and of residues of animals and plants that have accumulated at the bottom of oceans, lakes and seas. These include sodium chloride and potassium salt deposited on the bottom of reservoirs, silica, located in hot springs, and fossil fuels (oil, gas, coal), phosphates and limestone (coquina, chalk, etc.). Many minerals in this group have a layered texture.

• Debris. Formed as a result of weathering or displacement of parts of rocks by wind, glaciers or water and their subsequent accumulation. As a result, they are crushed and even more crushed. In terms of size meet small-, medium - and coarse-grained rocks. Such minerals applies pebbles, gravel, sand, gravel, clay.

Igneous rocks result from the crystallization of molten substances in the bowels of the Earth-magma. They make up more than 65% of the total volume of the earth's crust and are the most common minerals.

Recommended

"Knowledge is light and ignorance is darkness": the value, meaning and alternatives

There are some sayings that would seem to need no explanation, such as “teaching & ndash; light and ignorance – darkness”. But some still do not understand their meaning. But not only for such people is written by our article. I...

What was invented by Mendeleev for the army. The history and fate of the invention

D. I. Mendeleev was a brilliant Russian scientist-polymath, who made many important discoveries in various fields of science and technology. Many people know that he is the author of “Fundamentals of chemistry" and the periodic law of chem...

The origin of the Slavs. The influence of different cultures

Slavs (under this name), according to some researchers, appeared in the story only in 6 century ad. However, the language of nationality bears the archaic features of the Indo-European community. This, in turn, suggests that the origin of the Slavs h...

Magma is a silicate composition, saturated with gases and water vapors and molten up to 1200 degrees. She goes to the surface solely under the influence of various geological factors, where, cooling down, kristallizuetsya and forms rocks such as basalt, granite, olivine, pyroxenes, amphiboles.

Igneous minerals are divided into Intrusive and effusive.

• Intrusive rocks are in the subsoil at shallow depths. They have good crystallization and, depending on the geometry and shape, are divided into a batholith (large size), dikes (have a tubular structure and are formed as a result of filling of cracks), the veins (thin and long in length).
• Effusive formations occur at the exit of magma to the outside and consist of prescriptionno volcanic glass. Among the rocks of this type are allocated on a huge basalt plateau lava incrustations.

Depending on the depth at which lies the magma, there are three groups of igneous rocks:

• Plutonic – formed in the lower part of the crust of the Earth (partially or completely). To this type belongs the granite minerals.
• Volcanic – are formed on the surface. This includes minerals such as andesite.
• Hypabyssal-occur when magma filling cracks in existing rocks. This group can be attributed to the pegmatites.

Metamorphic rocks. This form of minerals is a igneous or sedimentary minerals, which, being in the bowels of the Earth undergo significant transformation. The changes that have occurred as a result of differential temperature, high pressure or chemical interactions cause the appearance of new textures and structures of rocks without affecting its chemical composition. The result is the same mineral, without melting and dissolving, is converted to another, more solid and resistant. For example, limestone turns to marble, granite to gneiss, Sandstone to quartz.

Thus, rocks of metamorphic, sedimentary and magmatic origin together comprise the thickness of the crust. These minerals are the main source of minerals used by man for material production.