Granite - interesting facts. Granite - composition and properties of stone Granite stone story for children

The modern construction industry offers consumers a huge amount of materials that can speed up, lighten, and embellish the result of repair work or the construction of new premises. However, natural stone has not yet lost its position. He is still in demand and popular. What can we say about our ancestors, who knew about the merits of natural materials, perhaps much better than us. No wonder they say that granite is a mineral: thanks to it, both architectural masterpieces and unique sculptures have survived to this day.

How was he educated

It is thanks to the way of its origin that granite acquired its unique properties. All its varieties are formed by volcanic eruptions: erupting magma flowed into the earth's cavities, located very deep below the surface. The enormous temperatures of these masses decreased gradually, and even under considerable pressure, which the layers of the earth located above exerted on them. As a result, igneous rocks fully crystallized, forming granite - a mineral.

Appearance and physical properties of the stone

Translated from the language of ancient Greece, its name means "grains", "grain". At the same time, the relative porosity of granite is rather low: even in coarse-grained varieties (the most “coarse” among all three structures), it rarely exceeds 6-7 mm. And in fine-grained varieties, the diameter of the grains does not reach two. At the same time, the size of the "cells" seriously affects the strength and longevity of the operation of structures made of this stone - the smaller their diameter, the stronger the granite.

Granite, in addition to its strength and density, is also characterized by decorative effect. It increases with polishing. The most common black variety, it is also the least valuable. Color options have both pink (up to red) color, and green, and yellow. Such rocks are widely used in architecture and construction.

Construction advantages of granite

This stone, especially its fine-grained varieties, is amazingly resistant to the influence of time: even after five hundred years, destruction is just beginning to appear. At the same time, it very successfully resists friction, is difficult to compress and is resistant to abrasion. Atmospheric influences also have little effect on granite. A mineral of this type is little susceptible to acids and practically does not absorb water, which makes it an ideal material for finishing embankments, including the coastal strip.

No less important is the fact that this natural stone is actually not affected by frost (very important in our latitudes!) And gets dirty very badly.

Granite also suits perfectly for decoration, as it harmonizes with metal parts, and with wood, and with ceramic parts, and with the most modern materials. Yes, and with all our fastidiousness, it is worth recognizing that natural stone perfectly keeps cool in summer and warm at home in winter.

granite aesthetic

In addition to purely utilitarian advantages, this stone has a good polishing that reveals its unique structure and richness of colors. But many designers are happy to use the unpolished structure of granite, which perfectly absorbs light and creates wild and unusual interiors.

A variety of color tones can satisfy even the most captious esthete: among the richness of tones, there will surely be something that he needs. Indeed, among all the facing and building materials, there is no other as attractive as granite - the photos fully reflect its beauty.

What is wrong with granite

As it should be, this huge "barrel of honey" necessarily has a "fly in the ointment". Among the shortcomings of this natural stone, it is necessary to note the residual radiation inherent in some varieties of granite. Therefore, it is mainly used for outdoor work. And those blocks that are intended for internal use must undergo a rigorous check so as not to subsequently harm people's health.

In addition, the increased strength of the stone, which has already been attributed to its undoubted advantages, is also its disadvantage. The extraction of granite is complicated by its hardness and fragility combined with it. You have to resort to expensive tricks to get a large enough piece of stone intact, and then invest a lot of work to bring it to perfection. That is why granite works are so expensive.

Development features

For most solid minerals, it is not so important in what form they are extracted from the vein, because their further processing (smelting, burning, etc.) is expected. Therefore, the crushing of the surrounding rocks does not harm the extracted substance, the main thing here is the convenience of the extraction itself. A completely different matter is facing materials, which include granite. For him, it is important to obtain a monolithic block without cracks and chips, since these defects cannot be hidden by any subsequent tricks. Moreover, such restrictions apply both during storage and during transportation, which greatly complicates the entire process. And if a message is received about minerals (granite is one of them), it is necessary to carry out a whole range of additional measures aimed at preserving the integrity of the mined.

The most common method

There are different ways of extracting granite, and the quality of the resulting stone directly depends on which one was used. At the moment, three methods are known, and, unfortunately, the most barbaric - explosive - is most often used. It consists in drilling a hole for a charge with which it explodes. The fragments are sorted, blocks are cut from the largest ones. For most miners, this method is attractive due to its cheapness. However, the quality of granite in this case turns out to be very low: the blast wave generates a lot of defects in the blocks, as a result of which their strength decreases. And there are not so many large fragments at the output - at least a third of the granite crumbles and is suitable only for processing into gravel.

air extraction

This is a more gentle way. The beginning is similar to the first option: a well is drilled in the right direction, a reservoir is placed in it, where air is pumped under pressure. This method makes it possible to use the granite deposit more fully, calculate the fault locations and avoid damage to the block, including even microscopic cracks. There are much more monoliths, and much less waste. However, the mining company will require upfront investment in equipment, and the method itself takes more time than explosive.

The most modern version

It is also the most expensive. It is called the "stone-cutting method" and requires the purchase of very expensive equipment and staff training. But granite (like any other natural stone) at the output is of perfect quality, without the slightest defect (both external and hidden). And the deposit is being developed by almost 100%.

Russian deposits

The extraction of granite in Russia, sadly, is carried out mainly in an artisanal, explosive way. This is despite the fact that there are a lot of deposits here. Such natural stone is mined in the Urals, in Primorye, in the Khabarovsk Territory, in Transbaikalia, in the Sayan Mountains. There are deposits in the Moscow region. Mining is mainly carried out by small private companies, whose volumes are steadily increasing, despite the fact that the main deposits are located in the Urals. They are developed with great difficulty due to climatic difficulties, which increases the required capital investment and increases the cost of granite. However, the growth in the number of people with high incomes increases the demand for natural stone and stimulates the development of this industrial sector.

Have you ever considered crushed stone, which is used in construction or for backfilling a railway track? Usually these are rather beautiful small fragments of a granular stone of gray or reddish color.

Stone grains shine brightly in the sun, and it is noticeable that the structure of the mineral is rather heterogeneous and consists of particles of different colors. With a high probability, we can say that the stone is one of the types of granite.

What is granite?

This rock is synonymous with hardness and strength. If they want to say something very durable, they say: harder than granite. Indeed, granite is the champion in terms of hardness among the rocks used in construction and decoration. Buildings erected from granite stand for hundreds, and sometimes thousands of years, surprising us with their beauty and durability. True, in ancient times this stone was rarely used for construction, since it is very difficult to process it, especially by hand.

Even with the naked eye it can be seen that the composition of granite includes particles of different rocks, i.e. its composition is heterogeneous. This is evidenced even by the name of the breed, which is derived from the Latin word "granum" meaning "grain, particle" .

Multi-colored grains form magnificent natural patterns, due to which granite is widely used for finishing private and public buildings, squares, memorial complexes, etc. High hardness and excellent frost resistance have made granite the most popular finishing rock, which perfectly resists the harsh Russian climate.

Origin of granite

In nature, granite of different types was formed in two ways:

- from a magma melt that cooled and crystallized in the depths of the earth's crust under high pressure, due to which an extremely hard and granular rock of high density was formed;

- from a mixture of clastic and sedimentary rocks mixed with alumina, which, during tectonic processes, plunged deep into the earth's crust and were exposed to a complex of factors - high temperature, high pressure and hot gases, which led to the sintering of particles of these rocks into a solid and durable conglomerate.

Granite was formed several million years ago. During this period, active processes of mountain building were going on on our planet, earthquakes constantly occurred and, layers of rocks rose to the surface, while others sank deep into the earth's crust.

Composition of granite

Granites of different grades include many types of minerals, but most are based on a combination of quartz and feldspar in various proportions, with additions of other minerals. The composition of granite can be roughly determined by the appearance of the grains:

- quartz - transparent or bluish, smoky-white crystals;

- gray and reddish grains - feldspar;

- transparent or black shiny plates - mica;

- potassium spar - cream or pinkish grains;

- oligoclase - yellow, greenish or bluish grains;

- plagioclase - pink grains.

Different grades of granite can have a gray, reddish, pink, greenish or almost black color, numerous color inclusions and small veins. The color scheme is determined by the minerals that are included in its composition.

Application of granite

Despite many excellent qualities, granite has found wide application only in the last two hundred years, when there was a sufficient technological base for its processing. The ancient and medieval world was content with softer marble and sandstone, and only relatively recently sawing and grinding methods have improved so much that it has become possible to quickly and efficiently process the hardest rocks.

Due to the almost complete absence of pores, granite is not impregnated with water, therefore it can easily withstand numerous cycles of freezing and thawing. This allows the use of granite slabs as the outer cladding of buildings and monumental structures, for paving streets and squares.

Polished granite is also used in interior decoration: floors are laid out of it, stairs and columns are made, walls, pools, and bathrooms are lined with slabs. Countertops, window sills, bathtubs and sinks are cut out of granite, sculptural compositions are made. But most of the stone mined is crushed and used as crushed stone for backfilling roads, concrete production and construction work.

Granite is a deep, acidic, intrusive (underground) igneous rock with a granular structure. The grain sizes vary from a few fractions of a mm to several cm in diameter. The main molecules of granite are potassium feldspars, acid plagioclase and quartz, a small amount of mafic minerals. Granite from intrusive mountain is the most common.

What is granite made of?

The main rocks that are present in granite: feldspars - the most common rock-forming minerals, they account for over 50% of the mass of the earth's crust. Feldspars belong to aluminosilicates of the framework structure. According to the chemical composition, feldspars are divided into 4 groups: plagioclases, potash, potassium, potassium-barium.Feldspars can be presented in various colors:

white
grey
yellow
pink
red
green

Quartz is a rock-forming mineral with a framework structure. It is characterized by transverse shading on the edges of the prism. It is one of the most common minerals in the earth's crust. A variety of chalcedony, amethyst, morion. Quartz is usually found in erupted rocks - rhyolites. Quartz is used in instrument making, optics as a semi-precious stone. Quartz can have different colors: colorless, white, gray, brown, pink. The density of quartz is about 2.5 - 2.6 g/cm3. It is classified as piezoelectric - that is, when deformed, it is able to induce an electric charge.

Mineralogical composition of granite.

Granite includes a wide range of minerals. Acid plagioclase is rock-forming minerals, aluminosilicates from the feldspar group. Plagioclases are a series of end-member minerals, which are albite Na(AlSi3O8) abbreviated Ab and anorthite Ca(Al2Si2O8) (abbreviated An). Usually, the composition of the rock is indicated by a number corresponding to the percentage of anorthites. Albit No. 0 - 10; oligoclase No. 10 - 30; andesine No. 30 - 50; Labrador No. 50 - 70; bitovnit No. 70 -90; anorthite No. 90 - 100.

Basic colors of granite. What determines the color of granite?

Minerals that make up rocks can have different colors. This is explained by the mineral composition of which the rock is composed. So if Si, Al, K, Na are present in the rock, then they will be colored in light colors (quartz, muscovite, feldspars). And if Fe, MgCa are present in the rock, they will have a dark color (magnetite, biotite, amphiboles, pyroxenes, olivines).

The color range of minerals

What rocks form granite?

Granite is a material that was formed from igneous rocks. Igneous rocks - are formed during the solidification of cooling magma both underground (intrusive) and on its surface (effusive). According to the content of alkalis, igneous rocks are divided into rocks of the normal series (that is, the ratio of the amount of alkalis to the content of alumina<1) , щелочного ряда (отношение >1). According to the silica content, SiO2 can be acidic (silica from 67 to 75%), medium acidic (from 67 to 52%), basic (from 40 to 52%) and ultrabasic (<40%)

What is made of granite?

Granite is a material that is used in the construction industry. But in order to use it, it must be processed and given certain sizes and shapes. After processing, this product is called crushed stone. can have various sizes, from 1 mm to 120 mm (rubble stone). Also, crushed stone can be classified by shape, that is, by the content of cube-shaped grains. The cuboid shape of crushed stone directly characterizes the level of adhesion with the binder components in the solution. The higher the cubical index, the lower the consumption of crushed stone and other materials, since it is more compact, which means there will be slight shrinkage, and therefore the structure will have increased rigidity. One of the types of products obtained is granite screenings or

Granite (from Latin granum - granule, grain) is a widespread intrusive igneous rock of acid composition. Liparite is an effusive analogue of granite. The presence of a granite layer is a key difference between the continental crust and the oceanic one.

The color of granites is light, mainly due to the color of feldspars: light gray, yellowish, pink, reddish. The structure is granular (uniform-grained or uneven-grained), and it can be coarse-grained, medium-grained, fine-grained, fine-grained. Density 2.54-2.78 g/cm 3 . Mohs hardness 5-7. The compressive strength reaches 300 MPa. Melting point 1260ºС.

Features. Granite is characterized by a granular structure, high hardness (leaves a scratch on glass), the content of feldspar and quartz, light color, low density. Granite is very similar to syenite and nepheline syenite. The difference is that quartz is absent in syenite and nepheline syenite; unlike nepheline syenite in the absence of nepheline.

Composition and photo of granite

Mineralogical composition of granite. It mainly consists of feldspar 60-65%, a lot of quartz 25-35%, a small amount of mica 5-10%, sometimes hornblende. Dark-colored minerals (hornblende, biotite) make up approximately 5-10% of the rock.

Chemical composition. SiO 2 68-72%, Al 2 O 3 15-18%, Na 2 O 3-6%, Fe 3 O 4 1-5%, CaO 1.5-4%, MgO up to 1.5%, etc.

Varieties:Granite rapakivi(rotten stone) - granite with large grains of feldspars. Structure: coarse-grained.

Granite Granite stones Cut of rapakivi granite

Origin of granite

Granite is an intrusive igneous rock. Granite magmatism is inherent in zones of collision of continental plates, where the thickness of the continental crust increases. Also, granites can be formed due to the recrystallization of sedimentary and other rocks under the influence of high temperature, high pressure and chemically active substances. This process is called "granitization".

Thus, granites may be of igneous origin and may be formed by granitization. Forms of occurrence: mostly batholiths, stocks, laccoliths, less often dikes of significant thickness. Forms of separation: flagstone, mattress-like.

Application of granite

Granite is used as a building and facing material. Blocks, slabs, cornices, curbs, parts of various machines and units for the pulp and paper, food (starch and syrup), machine-tool, metallurgical and porcelain-faience industries are made from granite. Since granite, unlike metal, is not affected by acids and salts, it is not afraid of moisture.

Millstones and rollers for mills are made from it. Granite tiles are a material for the manufacture of bases for precision instruments. Granite crushed stone is an important material for the manufacture of reinforced concrete products and structures, granite blocks - for the decorative design of buildings. Granite is used to make monuments, countertops, stairs, paving stones.

In the Black Hills, in Mount Rushmore, built of granite in honor of the 150th anniversary of US history, the world-famous bas-relief with portraits of four presidents is carved.

Portraits of US presidents in the granites of Mount Rushmore: George Washington, Thomas Jefferson, Theodore Roosevelt, Abraham Lincoln

Granite deposits

There are deposits of granites on every continent of our planet. The largest deposits of granites are found in places where the crystalline basement comes to the surface in Karelia: Kupetskoye, Dugoretskoye. The largest in Europe is the Shkurlatskoye deposit in the Voronezh region (near the city of Pavlovsk). Rapakivi granite has been mined for more than 100 years in the Leningrad region at the Vozrozhdenie quarry.

In the Urals, granite is mined at the Mansurovsky, Yuzhno-Sultaevsky, Golovyrinsky deposits. Gray and pink granites are found in the Caucasus (Kabardino-Balkaria) and in Yakutia (Taloy).

Granites of brick-red color are mined at the Verkhne-Chebulinsky deposit of the Kemerovo region, beige color at the Udalovsky deposit of the Altai Republic. Coarse-grained rock of a pinkish-orange hue was found at the Ushkanskoye deposit in the Krasnoyarsk Territory. Highly decorative amazonite bluish-green granite is mined at two deposits of the Chita region: Chalotuisky and Etykinsky.

Large deposits of granite are known in the Scandinavian Peninsula (associated with outcrops of the crystalline basement to the surface) and the USA.

This is a natural stone. It is mined in many places on our planet and it is likely that it is not found on other planets in the solar system. Therefore, it is granite in various sources that is called the "calling card of the Earth." This is one of the most durable breeds in the world. The composition of granite includes most of the known minerals: feldspar, quartz, as well as mica formations of various origins.

Is granite a mineral or a rock? This question is often asked by people who are just beginning to be interested in geology and mineralogy. In essence, it is a rock. As already mentioned, it includes various minerals, and its composition is heterogeneous, in contrast to minerals (for example, quartz, amethyst, chrysolite), which are uniform in both structure and color.

Rock granite is widespread in our life everywhere: in the form of railway embankments, tombstones, wall cladding, street elements of decorated decorations. Granite products have long been presented to people as the most ordinary and familiar to the eye. Often we just pass by without focusing on how different this amazing stone can be. Those who wish can get to know him better: after all, few people think about what granite consists of and what is the history of its occurrence.

How did granite come about?

It is generally accepted that there are two natural ways in which this natural stone was formed. It could arise from melted magma (solidified volcanic lava). In the depths of the earth's crust, magma slowly cools, turns into a petrified structure, in which grains of granite rock, having different sizes, crystallize for millions of years. It is no coincidence that its name itself comes from the Latin word "granum", which means "grain".

Natural stone granite is formed in nature in a different way. Sedimentary rock, as well as clay-like sand and heterogeneous stones, were gradually displaced by tectonic processes into the depths of the earth's crust. There, under the influence of high temperatures and pressure, substances melted and a process such as granitization.

Most of all, the formation of granite occurs in the so-called places of collision. Two continental plates collide with each other, which causes an increase in the layer of crust on the continent. Many scientists believe that it is as a result of the thickening of the collisional layers of the crust that layers of granite melt appear - at a depth of 10 to 20 km. This phenomenon has been named granitic magmatism . It is most typical for the Andean batholiths, as well as for island arcs.

Where are the granite deposits

The main place where granite occurs is batholith mountain ranges, the length of which is about 4 km, and the area is several hectares. Sometimes during mining it is seen that several layers of stone have formed: granite and its sedimentary rock. The stone itself looks like wide layers, alternating with representatives of sedimentary and metamorphic species.

Like other minerals, which are not very rare, granite has become widespread almost everywhere: it can be found on any continent . Due to the fact that over the course of millions of years, ancient rocks gradually forced younger formations upward, it came to the surface and became available for mining.

Chemical and mineralogical composition

As already mentioned, granite is a stone that has a granular structure in the form of crystals. The chemical formula of granite is represented by such basic elements as iron, calcium, magnesium and various alkalis.

Its main components are quartz, dark-colored formation minerals and feldspar. Spar provides certain shades, and if there is a lot of translucent grain in the stone, it means that it contains a lot of quartz.

Depending on what rocks are included in a particular stone, the mineralogical composition of granite can be different. For example, if it is dominated by plagioclase and there is little feldspar, it is called plagigranite. If, on the contrary, there is more feldspar in the stone, and less dark colors, this alasquite.

The chemical composition of the rock has the following scheme:

content feldspars(orthoclase and plagioclase) - from 60 to 65%;
quartz, providing high strength indicators - from 25 to 30%;
mafic minerals granite - from 5 to 10% (mostly biotites).

Depending on which feldspars are part of the stone, its color will also change. The most common is gray, on which different shades can appear: blue, pinkish, red, less often - greenish. Coloring also depends on what is included in the composition of granite from dark-colored minerals. If the seekers come across a rock consisting of biotite or hornblende, the stone will be painted in dark colors. There is a rather rare species called Yantsevsky, which has a pronounced shade of greenish color.

Properties

Granite is a rock that is distinguished by enviable strength, which is why it has been used in the construction industry since ancient times. The stone serves for a very long time, is resistant to rain and winds, and is able to withstand any climatic conditions. Few people know that the pyramids in Egypt are partially made of granite blocks. It was from this stone that many buildings in India and ancient Rome were built. It is processed and polished quite easily, and the degree can be brought to the point that the surface of the plate even becomes a mirror.

Compared with marble, this material twice as strong due to the fact that granite contains quartz. During the use of diamond drills. It is known that, despite its beauty and splendor, marble is very sensitive to temperature changes, which cannot be said about granite: it perfectly maintains its performance in the most severe conditions . Due to its strong structure, the stone much less susceptible to fungal attack than other materials .

The level of moisture absorption in the rock is low: the fine-grained structure of granite plays a key role in this. If it is denser - it is a breed with the best properties. They depend on the origin of the granite. The origin of the stone, in turn, determines the depth of its occurrence, it affects its density and strength.

The fact that granite is one of the most durable materials, and its performance is always at the right height, is largely ensured by the fact that it hardly absorbs moisture . This was the main reason for the use of stone for the design of embankments. By the way, the vast majority of the granite banks of the Neva were built under Peter I, which once again confirms the durability of granite.

Geochemical classification of White and Chappell granitoids

For the convenience of designating one or another type of granite stone, in the mid-70s of the last century, a brief analysis of granitoids was made based on their most common types.

In this analysis, four types of stone were distinguished - S, I, M, A:

Sedimentary (S)- the stone is the result of the melting of rocks of the metasedimentary type;
Igneous (I)- product of melting of substrates from metamagma;
Mantle (M)- a stone formed from magmas, which include tholeiite and basalt rocks.

The chemical composition of granite S is similar in most elements to granitoids I, with the difference that stones S contain little calcium and sodium. Later classification appeared type A granite , which differs in composition from subalkaline type stones and consists of a large number of incoherent chemical elements.

Classification of granitoids by grain structure

The size and structure of the grains of different types of stone is different from each other.

Based on this, granite is of the following types:

if the grain size does not exceed 2 mm - fine-grained;
grain size up to 5 mm - medium-grained ;
coarse-grained view - more than 5 mm.

The stone of the fine-grained variety will have the highest level of resistance to mechanical damage. It is characterized by more uniform abrasion over time, resistance to winds and high temperatures. The fine-grained fraction is always the most expensive. It practically does not absorb water and at the same time is highly resistant to fires.

When building houses, a coarse-grained type of granite is often used. It is cheaper, so after fires, you can often see granite stairs that have cracked and are no longer usable.

The names of granite, based on the mineral composition

Depending on what is the main mineral composition of granite, different types of stones are called differently:

not containing dark colored minerals - alasquite;
with a low content of dark flowers - leucogranite;
biotite- if this mineral in the composition of granite is from 6 to 8%;
if the stone contains biotite and muscovite at the same time - two-mica granite ;
if the stone contains micas from lithium - this is lithium fluoride granite ;
with a high content of alkaline components - simply alkaline granite ;
a rare species consisting of orthoclase, quartz rocks and augite - pyroxene.

Varieties of granite based on its structure

The grain structure of the stone also varies.

Below are the main types of granite, named based on the structure of its grains:

porphyritic- it is characterized by brightly standing out longish inserts. They differ from the main body of the stone in that they protrude from it. These are quartz, orthoclase, microcline.
Granite pegmatoid - differs in symmetrical and uniform level of granularity.
Rapakivi- Finnish type of stone with rounded inserts (red with a gray or gray-green frame).
gneissic- the most common stone, having a fine-grained structure.

Of course, for a person who first encounters the fact that there are a lot of varieties of granite, it can be difficult to figure out which one is the best. It all depends on the purpose for which it is planned to use this material. There are a lot of options for use, and the quality and reliability of granite is much higher than that of the more popular marble.

It is known that marble quickly darkens and deteriorates under the influence of temperature changes and high humidity, and granite will stand for a very long time without changing either the structure or the original color of the stone. In addition, for lovers of white stone, there are special types of granite, which, when properly processed, are indistinguishable from marble at first glance.

Thanks to the excellent performance characteristics of granite, which has proven itself for many centuries, it is always possible to use it as a reliable building material, as well as for making decorative elements. Since any product made from this stone is unpretentious in use, this stone does not require special care. It will stand up to any bad weather and will serve for centuries.

The only disadvantage of granite is that among building materials it has the greatest weight, which must certainly be taken into account when designing bridges, monolithic houses and other large structures.