Granite is the most numerous in the continental crust magmatic intrusive rock.The name of this excellent natural material was due to its porous granular structure (from the Latin. Granum - "grain").Granite refers to acidic species due to the fact that it contains a large amount of silicon dioxide - SiO2.Furthermore this item is included in the granite alkali and magnesium, iron and calcium.This rock formation is considered one of the most durable, solid and durable, its density equal to 2600 kg per cubic meter.In this article we look at the composition of granite, as well as describe the existing classifications of rock reveal its properties and characteristics.
origin and place of occurrence of granite
believed that granites were formed over a long period of geological history all over the world.Versions of two breeds of origin under consideration.The first states that granite is formed as a result of magmatic melt crystallization process.According to the second theory, we are considering the stone was formed under the influence of ultrametamorphism.Under the influence of pressure, heat and fluids rising from the deep layers of the earth, the process of granitisation.A large number of fields of a heavy-duty rock, including the US, China, Brazil, Scandinavia and Ukraine.In our country, there are also rich deposits of this natural material.It is obtained fifty granite quarries, including the Arkhangelsk and Voronezh regions, as well as in the Caucasus.Most close to said ore deposits are different, including tin, copper, zinc, tungsten, molybdenum and lead.
consider that part of the granite.Feldspar and quartz
According to its components, this rock belongs to polymineral, that is not composed of a single component, but several.One of the main elements that make up the granite is feldspar.It is a mineral silicate group.Typically, its faces at least 50%, and then all 60!This rock-forming mineral is present in the rock in the form of potassium feldspar (orthoclase, adularia) and acid plagioclase (oligoclase, bytownite, Labrador, and so on. D.).Another important component is quartz granite - very hard rock-forming mineral vast majority of igneous rocks.Its share is not more than 30% of the total consideration of the breed.Embedding it look like small glassy grains.In the natural state of the quartz is colorless, but as a rock composed of granite takes on different colors - yellow, pink, red, purple, and so on. D.
mafic minerals and other impurities in the composition of granite
addition of quartz and feldspar in the acidrock there are also other inclusions.They usually occupy no more than 10% of the total.It biotite, lithium mica, muscovite and hornblende.A small proportion of occupied accessory - for example, apatite and zircon minerals and alkaline - tourmaline, garnet and topaz.Thus, we examined the composition of granite.Diagram illustrates the basic components of this natural material.
kinds of granite
Depending on the characteristics of the mineral and chemical composition of granite, allocate some of its varieties.One method is built on the ranking percentage of plagioclase in the rock.The following types of granite:
- alkaline feldspar (plagioclase less than 10%);
- proper face (from 10% to 65% plagioclase);
- granodiorite (from 65% to 90% plagioclase);
- tonalite (over 90% plagioclase).
addition to the percentage of feldspar, as a basis for distinguishing between types of stone is taken under consideration the content of minor mafic minerals.According to this classification, distinguish these species breed Alaska - granite, not including a dark-colored metal and leykogranit - having a low maintaining them.Two-mica granite - is, in addition to feldspar and quartz, muscovite and biotite, and also contains an alkaline aegerine and amphibole.
Structural features of the breed
There is another classification based on structural and textural features of said rock.Mostly granite has a granular crystalline structure, but sometimes it happens and porphyry.The environment is a massive material layers, formed as a result of cooling magma.Due to the fact that it freezes unevenly granite is formed having a different structure, including fine and coarse.Samples of the latest called granite porphyry.An example of porphyry rocks with coarse-grained structure can be a granite rapakivi (Finland).It has blotches orthoclase size of a chicken egg.
Painting granite
minerals that make up the granite may stain the rocks in different colors.As a rule, orthoclase determines the color of the stone.The most common is a light gray color.In Russia, widely distributed material red.The mineral composition of granite with bright color included feldspar, hematite crystals having otherwise - iron oxide.They give the rock a blood-red hue.Also, across the stones yellow, blue and pink colors.Emerald hue breed gets green by potassium feldspar - amazonite.Sometimes unusual granite are the rainbow colors.It occurs because of feldspar, possessing iridescence.Often it oligoclase and labradorite give a beautiful iridescent shimmer, especially noticeable when turning stone.That such an interesting material granite.
composition and properties of rocks
This natural material has a lot of great features that make it irreplaceable in many areas, especially in the construction industry.Firstly, granite durable.It can serve for a long time, while maintaining its original appearance.Sometimes it is called by the people "eternal stone", and all because of him absolutely nothing going on for centuries.Secondly, this material has an extremely high durability.Products from it are not subject to wear.Quartz - a mineral composed of granite - makes this rock so solid that when it is processing, grinding and cutting blade is used with a special diamond coating.Third, one of the most important properties of granite is its resistance to any environmental influences, and to acids.It does not require processing and protection from a variety of oxidative and physical influences.Only at temperatures above 600 degrees, he may change the structure or cracking.Fourthly, granite is resistant to moisture, it is practically watertight, does not absorb water and is not subjected to degradation due to precipitation.For centuries, buildings and monuments made of granite can maintain its original appearance.Finally, not least, that granite harmless.It is completely safe for humans.All these properties make the considered rock valuable building material.
Application granite
Said stone is widely used for construction and facing works, as are durable, resistant to environmental influences and special durability.Because of the resistance to abrasion and compression, it is very often used in the external and internal decoration.Granite has a high resistance to contamination, so it is often used in the manufacture of handrails, stairs, columns, countertops, window sills, bar counters.Most granite slabs are made fireplaces and fountains, because it is resistant to temperature changes, and to absorb moisture.On the outside, this breed is often used as cladding, masonry and building materials.Granite cobbles spread sidewalks, roads and bridges are often trim the pier, streets and squares.Because granite is made fences, retaining walls, they adorn the facades and walls of buildings.And this can be used to breed a variety of colors.In Russia, the most commonly used gray, white, red and brown varieties.Unfortunately, the extraction and processing of igneous rocks is difficult and expensive, so this material is rarely used for the construction of conventional buildings.It is mainly used for the decoration of objects with significant architectural value.
Architectural monuments of granite
After proper grinding of granite surface becomes a mirror, both reflecting and absorbing light rays.Therefore, the stone looks very rich and impressive, it can be used for the manufacture of monumental sculptures and architectural compositions.An example of beauty, elegance and durability of granite can act monuments, historic buildings and structures erected in many countries, including in Russia.Any granite structure is of particular grandeur and monumentality, hitting the imagination of its power and beauty.
