Granite: properties and application of stone
Before listing the properties of granite, it should be said that it is a igneous rock consisting of mica, plagioclase and quartz. It is one of the most durable, solid and dense rocks on Earth, and therefore is widely used in many industries and fields. Most often, of course, as a facing material. What are the properties of this substance, since it is so valued?
The main features of the rock can be distinguished in the following list:
- The density of granite is 2600 kg / m³.
- Melting point is 1215–1260 ° C. If there is water and the corresponding pressure, then the indicator decreases to 650 ° C.
- Compressive strength - up to 300 MPa.
It is worth noting that granites are often found in the continental crust. Like their effusive counterparts, known as "rhyolites." In composition, they are similar. Rhyolite is also a igneous volcanic rock of a glassy type, which contains quartz, sanidine, plagioclase and other impurities.
Granites are widely distributed, it is from them that the base of most of all earthly continents is laid.
Components in granite, the properties of this rock is determined to a large extent. Here are the components of which it is composed:
- 60-65% - feldspars. These are rock-forming minerals from the class of silicates. In granite there are plagioclase and potassium minerals (sanidine, microcline, adular and orthoclase).
- 25-35% is quartz. Also applies to rock-forming minerals. In the earth's crust is contained in the amount of 12%. It is actively used for the manufacture of parts of ultrasound generators and optical devices, consumed by the ceramic and glass industry.
- 5-10% - mica. Biotite, to be exact. It is a substance containing iron, magnesium, aluminum and potassium.
The chemical composition also to some extent determines the basic properties of granite. This is how it appears:
- 68-73% - silicon dioxide (SiO2).
- 12-15.5% - aluminum oxide (Al2O3).
- 3-6% is sodium oxide (Na2O).
- 1.5-4% - calcium oxide (CaO).
- 0.5-3% - iron oxide (FeO).
- 0.5-2.5% - amphoteric iron oxide (Fe2O3).
- 0.5-3% - potassium oxide (K2O).
- 0.1-1.5% - magnesium oxide (MgO).
- 0.1-0.6% is titanium oxide (TiO2).
A few words should be said about the chemical weathering of granite. Under this concept is meant the destruction of the rock in the place of its occurrence.
When granite is weathered from feldspars, kaolin (white clay) is formed. It is then redeveloped as sedimentary rock. But besides it, clay minerals are still formed. But quartz remains unchanged. Mica, in turn, turn yellow. That is why, by the way, they are called "cat gold."
Now you can go to the properties of granite. The main is strength. This material cannot be deformed by acting on it mechanically or with the help of temperature differences. The latter is not at all scary this rock. Granite will equally “feel” itself both at +50 ° C and at -60 ° C. It is not susceptible to fungal infections, it is resistant to fire and acids.
Even in the most extreme conditions, granite remains flawless, retains its strength. Which, of course, makes the process of cutting and grinding it very specific - only diamond tools are used in these processes.
It should be noted that the strength depends on the coefficient of moisture absorption, which is equal to 0.2% in granite. This indicator is superior to all other materials. But he depends on the place of extraction of rock.In dense fallow layers, for example, granites contain better characteristics. And the depth at which the rock is laid determines not only its density and strength, but also the area of further use of the stone.
Listing the properties of granite, it is necessary to note the attention and its visual appeal. Perhaps this is not the most colorful stone, but the poor color palette of this rock can not be called.
Gray granite is the most famous. This shade is due to the presence in it of the notorious feldspars. There is also amazonite granite, which differs in bluish-green color. Slightly less often stones with a pink, orange and red shade meet.
Very beautiful black granite. This color is caused by quartz. More often it gives colorless granules in the texture of a stone, but black copies come across.
Especially aesthetic looks amethyst rock, a feature of which is a purple-pink hue. But the rarest specimen is a mineral in which blue quartz is present.
It is important to note that the pattern of the stone depends on the accumulations of dark color. These are varieties of quartz and feldspar.The more of them, the more diverse the picture. But most often there are stones with a speckled, spotted pattern. Slightly less - minerals with banded patterns.
There is also granite with “rings” of black biotite and quartz, interspersed with sparkling crystals. If they are stretched in one direction along the axes, then when sawing a dotted-banded pattern is formed. So the composition and properties of granite make it an excellent finishing material.
In addition to the above, I would also like to note the following useful properties of granite:
- Durability. Due to its composition and strength. Fine-grained varieties of granite, which are the highest quality, show the initial signs of abrasion only after 500 years. It is not surprising that he was called the "eternal" stone.
- Water tightness and frost resistance. Due to these properties, granite stone is used in facing embankments.
- Ecological purity. This stone is not radioactive, which determines its safety for the environment and humans.
- Ease of processing, richness of textures and compatibility with absolutely any building materials.These features make granite indispensable in the finishing works.
By the way, despite all its advantages, this material is relatively inexpensive. The price of one square meter starts from about 2 500 rubles. There are, of course, more expensive copies, but the “starting” mark is really pleasing to the eye.
Talking about the basic and additional properties of granite, it is impossible not to mention the origin of this material. It is interesting that, unlike other igneous rocks (norit, basalt, troctolite, gabbro, anorthosite, etc.), its existence on other planets is only indirectly known. Therefore, geologists say that granite is the card of the Earth.
However, it originated from the same substance from which other terrestrial planets originated. Therefore, the problem of the origin of granite remains unresolved.
However, it is known enough how this stone appeared. However, the process of formation of granites raises questions. When melting rocks containing amphiboles, you can get only 20% of this material, and then with a low content of potassium. There is an assumption that the granite found in nature was once lowered into the upper mantle, but there is no direct evidence for this statement.
There is also a version according to which this material is the last differential of basalt melts, enriched with potassium, sodium and silicon, formed due to the crystallization of magma.
In the field of construction
Above were considered the basic properties of granite. And about the use of this material is now worth telling in detail. So, it is used:
- In the decoration of the ceiling, floor and walls. Granite is relevant in any interior.
- In the manufacture of balusters, steps, countertops, window sills, fireplaces, cornices, baseboards, columns, statues, vases.
- Outside the premises. It is used not only for cladding, but also in construction. Most often granite trim basement. So it is possible to protect it from moisture and other damaging factors.
- In the decoration of walls, the manufacture of pillars, stairs, balconies, gables, fountains, shops.
- When building a foundation and walls. They turn out especially strong, perfectly keep a cool in a hot season and do not pass a cold in the winter.
- In the construction of buildings with an increased radioactive background. These include boxes, storage, etc. This stone copes with chemistry and radiation, not letting it out.
Talking about the properties and application of granite, it is also worth mentioning the existence of such material as granitoid. This is still the same stone, but with the addition of other substances of natural origin. From granitoids turn out especially strong houses, distinguished by their unique strict beauty. Such buildings can defend centuries, and their attractiveness will not fade.
The houses of this material are not destroyed by precipitation and wind, they are easy to clean with simple water or detergents that do not harm the surface. Granite and its derivatives are very popular in many countries, since buildings on this basis provide a guarantee of reliability. There is no doubt about the quality. Granite will always be appreciated, because it is made by nature itself and is able to add elegance to any room.
Place of Birth
It lies in the form of batholith granite. They form a huge array, the area of which reaches several hectares. Its deposits are often in the form of intrusive bodies (dikes, stocks). Granite is also represented by layer-shaped bodies, between which accumulations of metamorphic and sedimentary rocks are found.
The deposits of this stone are spread all over the Earth. They are in the north of the United States, in the Black Hills, on the shores of the Atlantic Ocean, on the Ozark Plateau. Granite is mined in Vermont, South Dakota, Georgia, Wisconsin. And in Russia there are about 200 deposits of this breed at all. The largest are Malokohnovskoe and Mokryanskoe.
Granite is also mined in Eastern Siberia, in the Karelian-Kola region, in the Far East and the Urals, in the Caucasus. But the leader in terms of deposits is Italy. Most of the deposits are concentrated in Sardinia. Rare amethyst and pink rocks are mined there. And, if we talk about Europe, there is granite in Sweden, France and the UK.