Limestone properties and applications 3. Minerals: Limestone. Breed color classification

So what is this extraordinary stone - limestone, which will be discussed? Why is he so good that legends, fairy tales, poems are composed about him? Why do architects and designers like to work with him, although now there are many other stones on the construction markets, including artificial ones, and all sorts of other materials? Maybe it's better to clad the facades of buildings with artificial stone made of colored concrete - both easier and somewhat cheaper? But no, the eye is pleased with natural, noble and not subject to temporary destruction of limestone. Almost forgotten in the 20th century by Russian architects and builders, it comes back into fashion and strengthens its position in various styles. To know in which climatic zone one or another type of limestone can be used, one must understand the structure of any stone and pay attention to its characteristics.

Limestone stone is a sedimentary rock consisting of calcite with the inclusion of sediments from small marine animals that have been compressed over millennia into stone deposits. After the retreat of the seas, huge stone expanses remained, consisting mainly of limestone. Its deposits are found throughout the earth, somewhere more, somewhere less, as the seas slowly migrated over land.

Limestones, diverse in their structure, are divided into several types:

shell limestone;
calcareous tuff;
ordinary and limestone;
marbled and dolomatized limestones;
earthy limestone.

Limestone, consisting of a mass of shell valves cemented together by carbonic lime, is called "shell limestone". It differs from ordinary limestone in color and quality characteristics.

Its color varies from light cream to brownish or grayish and quite dark gray.

Some of the limestones of this genus are distinguished by a dense cementing substance and better preservation of shell valves. Others, on the contrary, are loose and porous. Limestone-shell rock is used in construction, it is well sawn, architectural decor is made from it, wall blocks are made that go to the laying of houses, or a facing slab is produced. It is mainly used in warmer climates, that is, in the south of Russia. Limestone-shell rock has low density and frost resistance. Most actively it was used and is used in the construction of buildings in Dagestan.

Calcareous tuff - which is freshwater limestone, or limestone. An excessively large amount of carbonic lime, dissolved in water from various sources, was deposited under atmospheric pressure on plants, shells, and grains of sand. It turned out limescale, which through the millennia, through complex lithogenesis, turned into tuff. Tuff, like shell limestone, has a porous structure. When sawing, grinding or polishing, it becomes beautiful and acquires a more saturated color. Tufa slabs that have too many pores are “healed”, that is, the pores are rubbed with some special mastic or resin to match the color of the stone, then the tuff is polished or polished, which gives it beauty and aesthetic charm. Freshly mined tufa is extremely soft and porous, but it gradually hardens when exposed to air. In some countries, calcareous tufa is called "travertine". It is suitable for cladding facades of buildings, as well as for interior work.

The concept of "calcareous tuff" (formed from freshwater sediments) should not be confused with the concept of "volcanic tuff" (which is the product of a secondary formation from volcanic eruptions, similar to how sandstones were formed from collapsed quartz rocks). Of course, the best building materials are ordinary, or dense, limestones. They differ in fine-grained or completely dense addition. The color of ordinary limestone, depending on the coloring impurities, is white, yellow, pink, red, green, blue, gray, black with various shades. On ordinary limestone specific gravity higher than, for example, that of a shell rock; water absorption from 1% to 9%, frost resistance not less than 25 cycles (the cycle is the state of the stone from the initial ingress of moisture to freezing, followed by a sharp thaw). Such limestone serves as a raw material for the manufacture of piece ornamental and facing stone, as well as products from it. It is easy to work on machines and by hand, it feels great in any environment: on the walls, on the floor, in the landscape, in hot and cold climates, and even in the aquatic environment.

But among ordinary limestones, there are also more dense stones. This is explained by the fact that in the process of subsequent lithogenesis, limestones acquired the properties of marbles and dolomites. Such limestones are not only well sawn, but perfectly polished and polished. "Marble" limestones are especially good. Sometimes they contain various fossils, shells, the remains of crinoids, fish and various plants, due to which they have a very beautiful pattern when polished. Limestone glistens like marble (“marble” in Greek means “brilliant”). It is especially beautiful in facing the facades of buildings, walls inside the premises, as well as in laying floors. This limestone can be "aged" artificially to look like a stone of the 15th, 18th, 19th centuries, but only when it is laid on the floor, special chemical impregnations will be required. Marble-like limestones have an increased resistance to adverse weather conditions, they have a sugar-like fracture, fine or coarse-grained structure, water saturation up to 0.8%. Such limestones are not only a good building material - they are also used to make complex architectural details: columns, pillars, balusters, brackets, cornices. belts, cabinets, vases and more. When installed in external environment parts from it do not require special care. This limestone does not suffer from temperature differences in winter and summer. It not only has a higher density, but also high frost resistance, it can reach up to 300 cycles in laboratory conditions. “Dolomatized” limestones have very similar properties. Their water absorption is 0.3%. they are dense, with a high specific gravity and low abrasion. Such limestone also has high frost resistance, which is very important in the Russian climate. But the disadvantage is that under the influence of various atmospheric phenomena, as well as sunlight, polished or polished dolomatized limestone fades, loses color and becomes gray, inconspicuous. Therefore, polished dolomatized limestone with beautiful quartzite inclusions is best used for interior cladding. Only when facing the facades of buildings in the form of “rock” tiles, which are manually processed - chipped from all sides, dolomatized limestone looks great.

"Earthy" limestones, like gypsum stone (alabaster), due to their low strength, are used only for the preparation of artificial materials.

Since limestones are shallow, they are mainly mined in quarries. open way. Piece stone is mined in the upper layers, lime crushed stone of various grades is made from the lower layers. In deep quarries, special machines are used for sawing blocks, these blocks are then delivered to the surface, to workshops and the floor is sawn to certain sizes.

Where the stone sawing and processing shops are located near the quarry, the cost of this stone becomes lower. The cheapest stone is limestone in its raw, “wild” form, and it is also beautiful and noble. Such limestone can be used in construction as a rubble stone for laying walls, it can be used for cladding in the form of a thin slab of various formats. It looks great on the facade of the house, on the fence against the backdrop of bright greenery. Romantic, beautiful, comfortable: once revetted and no problems: no need to paint, plaster, restore ... It's forever!

For the book "Frozen Music in Stone"

In contact with

Data-lazy-type="image" data-src="https://karatto.ru/wp-content/uploads/2017/12/izvestnyak-1.jpg" alt="white limestone" width="350" height="204">!} Limestone stone is familiar to everyone: both malleable chalk and durable marble are, in fact, it. The mineral is inconspicuous in appearance, not rare in nature, not whimsical in processing. And with all this, he managed to become famous in culture and history: the ancient Egyptian pyramids, majestic temples and cathedrals, the famous Chinese Wall, the Moscow Kremlin and other masterpiece buildings were created from it. Many signs are associated with it, truly miraculous properties are attributed to it. The origin of natural limestone, its varieties, various uses will be discussed further.

Characteristics and origin of the calcareous mineral

Natural stone limestone is a non-solid sedimentary rock with a maximum content of calcite. The rest in the mass of the mineral is inclusions of particles of other substances (silicon, phosphates, quartz, lime, etc.). Also, in the mass of calcium carbonate, microparticles of the skeletons of simple organisms can come across. The origin is generally characterized as organic, but there is also an organo-chemical way of mineral formation.

The limestone mineral is mainly formed in the shallow environment of the marine basin. .jpg" alt="natural limestone" width="300" height="225">!} Freshwater conditions also allow limestone to be deposited. Its usual form of occurrence is a layer. It can be deposited on the principle of salt: when water evaporates from lakes and lagoons. But the bulk of the stone originated precisely in sea depths, where there were no intensive processes of evaporation and drying.

The natural mechanism of mineral formation begins with the work of living organisms. They extract calcite from sea water and build shells. Then the remains of their skeletons accumulate on the bottom surface in a huge mass. The most telling example of calcite carbonate formation is the birth, growth, and death of coral reefs. It is not uncommon when piece shells are found at a break in limestone rock. This variety is called the shell rock.

Other species are also named according to the types of organisms and their metabolic products:

nummulite;
bryozoan;
oolitic.

Marble-like limestone is a separate category. It, in turn, is divided into massive-layered and thin-layered types. Under the influence of certain temperatures and pressure, it changes the structure of crystals and transforms into marble.

Limestone properties

Data-lazy-type="image" data-src="https://karatto.ru/wp-content/uploads/2017/05/formula-pn.png" alt="" width="47" height="78"> As already mentioned, the lion's share of the composition of the mineral falls on calcium carbonate. Its chemical formula is CaCO3. The properties of this compound allow it to dissolve in water. In nature, this process is of global importance: in this way, limestone becomes an important participant in the formation of karst forms of underground relief. CaCO3 also decomposes under certain conditions into a number of bases, where the most voluminous is carbon dioxide. This reaction also plays a global role in natural life - natural carbonation of mineral waters occurs.

By color, the varieties of the mineral are characterized as follows:

Traditional tones are light gray, white or cream.
Color - pinkish, yellowish, reddish, blue and black.

Shine as a specific feature is absent. Density: - / + 2.6 points. Frost resistance and thermal insulation of high rates.

During the firing of the rock, quicklime is formed - one of the oldest building materials. And when it is dissolved in acetic compounds, an aggressive reaction is obtained with hissing, seething and complete dissolution of the mineral. This, by the way, is the surest way to distinguish natural stone from fake.

Place of Birth

Some mountain ranges are entirely composed of this mineral. The breed is widespread in the massifs of the Alps and the Crimea. Of the continents, it is still rich in stone North America, but Australia is lagging behind in this sense: its constituent rocks do not contain calcite. The most fruitful deposits are concentrated in the Caucasus, in Siberian region, in the Urals. China is an important supplier construction variety mineral - marl. A very promising modern source of limestone is the Zhdanovskoye deposit, which is developed on the territory of the Russian Federation in the Orenburg region.

The main areas where limestone is used

Over the entire period of its existence, people have deeply learned the properties of this natural gift and learned how to use it with maximum benefit. Here are the main areas of human activity where limestone is an important material:

Construction. Varieties of stone were useful here in everything: in the construction of stable high-rise buildings, in facade cladding and for paving surfaces.
Landscape design and architecture. Ease of processing and decorative properties in these areas are highly valued, especially when it comes to layered types of mineral with a characteristic weathering relief.
Production of finishing materials. Here the emphasis is not on decorativeness, but on the organic origin of the stone.
Cretaceous rocks are used to make crayons, tooth powders, and expensive high-quality paper.
Cable production is not complete without coating welding electrodes with limestone compositions.
Printing widely uses lithographic limestone to create highly artistic engravings.
Jewelry business. Translucent pastel shades are appreciated. The best design and decorative combinations are obtained with silver and cupronickel frames.

Limestone in lithotherapy and magic

absorbent;
hypoallergenic;
antiseptic.

Data-lazy-type="image" data-src="https://karatto.ru/wp-content/uploads/2017/12/i1-300x225.jpg" alt=" processed limestone" width="300" height="225">!} For any disease, it is considered useful to drink water that has been purified by calcite. It is also believed that limestone stones purify and disinfect indoor air. Limestone can cause harm only to those who mine it - inhalation of the dust of the mineral and its settling in the lungs does not have the best effect on health.

There is a whole gradation of the healing properties of limestone according to color:

Reddish calcite. It treats nervous feelings and blood diseases.
Yellowish limestone. For meditation and regulation of digestion.
pink varieties. Nervous disorders, healthy sleep.
Blue limestone. Pressure drop.

The therapeutic effect is achieved by contact with the stone: it is applied to the diseased area. You can just hold it in your hands with individual attacks and manifestations of the disease.

In magic, a legend is associated with a stone that it develops the extrasensory abilities of each person, opens the way to clairvoyance. This is a talisman from laziness and for creative imagination. Astrologers have included limestone in the list of universal stones suitable for most zodiac signs.

Jpg" alt="Scorpio" width="50" height="50"> Исключают только Скорпионов – среди них больше всего людей, склонных к оккультизму и чёрной магии. А известняк по своей ауре – проводник светлой энергии и высоких духовных вибраций. Мистическому уклону Скорпионов это противоречит, и талисман-известняк «не дружит» с волевым и агрессивным знаком.!}

As for the rest, the mineral willingly shares its invigorating and inspiring properties and helps the owner to see the outcome of the situation.

Limestone is a natural stone, which is a soft sedimentary rock of organic or organo-chemical origin, consisting mainly of calcite. It is not uncommon for limestone to contain impurities of silicon, phosphates, quartz particles, grains of clay and sand, as well as lime.

In this review, we will take a closer look at what limestone is, its origin, varieties, colors, applications and much more.

Origin of limestone

The formation of limestone in most cases occurs in areas where shallow sea basins are located, but there are limestones formed in fresh waters. The limestone deposit is formed in the form of sheet-like deposits, but in some cases it can be deposited in the form of salts and gypsum from the evaporating waters belonging to marine lagoons and lakes. But, nevertheless, its main part is deposited in the depths of the sea, which were not subjected to intensive drying.

The origin of the main varieties of limestone originates from the formation by marine organisms of calcium carbonate compounds from salty sea water, which are necessary for the formation of a skeleton and shells, which then accumulate on the bottom of the seas after the end of the life of marine life. One of the clearest examples of the accumulation of calcite, or calcium carbonate, is the coral reef. That is why, in some cases, on a cut of limestone rock, you can find the remains of shells, or whole small shells.

Formed on the seabed Coral reefs experience the constant impact of the sea current, waves and surf, under the intense force of which the destruction of the existing reefs occurs. As a result, the limestone fragments located on the seabed and calcium carbonates are mixed, and the remains of ancient rocks (calcites) that have undergone destruction are included in this process of forming a young limestone rock.

Varieties of limestone

Limestone has great amount varieties, classified by color, composition and origin, as well as by field of application and structure.

In accordance with the varieties of impurities that make up limestone, this rock is divided into the following color groups:

White and gray limestone are pure rocks that do not contain any impurities;
Gray and black limestone are a fairly rare rock that has organic components in its structure;
Brown and red limestone are rocks containing manganese components;
Greenish shades of limestone are composed of organic impurities, consisting mainly of seaweed;
Yellow and brown limestone contains iron components.

In accordance with the chemical composition and structural features of the rock, there are the following varieties of limestone:

Dolomitized limestone, including in its composition from 4.5 to 16% magnesium oxide compounds. If there is an increase in the percentage of the content of this compound in limestone, then it is reborn into dolomite rock.
Marbled limestone contains a high percentage of organic matter in the form of mollusk shells. Differs in an unusual palette of colors, ranging from beige flowers to gray-blue shades.
Earthy formations, which are chalk.
Nummulitic limestone formed by the remains of unicellular microorganisms.
Coral limestone, or as it is also called shell rock. This variety of natural rock consists mainly of shells and shell remains from other inhabitants of the sea.
Clayey limestone, which has an intermediate composition between limestone and marl rocks, and the percentage of carbonate and clay can have different values. These formations of rock have a softer structure than other varieties of limestone, but are more fragile than shale deposits.

Types of limestone rocks

In accordance with the history of origin, the breed in question is classified into the following varieties:

Marble, or Jurassic limestone, which has a multimillion-year history of origin, has a high level of strength, density and fine-grained structure. This limestone was called marble in the medieval era due to its susceptibility to polishing processing methods.
Putilovsky limestone, which has extraordinary physical characteristics, a low degree of moisture absorption and abrasion. At the time of the construction of the famous St. Petersburg, this material was the basis of all construction. Received such a name in honor of the Putilov quarry, located in the Leningrad region, where it was mined.

Regarding the field of application, there is a flux limestone used in the field of metallurgy, for the manufacture of flux and metal smelting, as well as facing. The latter type of rock is used in construction as a facing material to create an unusual color on the exterior and interior of buildings.

Among other things, separate varieties are distinguished in accordance with the macro texture and the main features of the bedding of the rock: these are fissured, layered, platy, landslide and cavernous limestone.

Physicochemical characteristics

The basis of the chemical composition of white limestone, which does not contain any impurities, is very close to calcites. It also includes:

dolomite components in concentration less than 1% (MnCO3, CaMg(CO3)2, FeCO3);
clay aluminosilicate and silica minerals, in the form of opal, quartz and chalcedony;
a small concentration of oxides, hydroxides and sulfides.

Very important! Limestone rocks include natural formations containing at least 50% calcite in their composition.

in construction;
at cement enterprises;
in the road industry;
in agriculture;
in the metallurgical industry as a flux additive for metal smelting;
in food and glass production;
in the pulp and paper industry;
in the leather business and the production of paints and varnishes.

The use of natural material can be various types, namely:

as limestone rubble;
in the form of rubble, piece, or lumpy stone;
in the form of sand;
facing plate;
mineral wool and limestone flour.

In the construction industry, this rock is used for arranging the foundation of buildings in combination with lime and concrete.

The crushed rock is used to add to the composition of the road surface, which are intended for laying the roadbed for cars.

Moreover, this material is used to make soda in the food industry, and is also part of the mineralized fertilizers needed in the agricultural industry.

limestone slabs

Limestone slabs are a unique cladding material used for cladding a variety of surfaces. With the external cladding of buildings using such tiles, any structure will be ennobled, and its service life will be noticeably longer.

IN country houses facing plates are used for facing of pools, landings, sidewalks.

Among other things, facing plates have found their application for interior refinement of interiors. They trim walls, floors and window sills from the inside of buildings.

Extraordinary color range finishing material expands the design possibilities for creating unique compositions for a bar counter, countertop, or fireplace.

Influence of climatic conditions

Limestone is a very valuable building material due to its low density, accessibility to various processing methods and a wide range of external indicators.

Humid climate conditions with a high level of humidity contribute to a decrease in the strength of the rock. Here an important factor is the heterogeneity of the structure. this material and its diverse density spectrum, which must be taken into account when choosing the type of building material and the conditions in which it will be used.

The level of strength and operating time also depend on the frost resistance of the rock. Crystalline varieties of limestone have high frost resistance, but only if they do not have pores and cracks.

To prevent sudden destruction of the building material during its operation, it is imperative to take into account its above-mentioned characteristics.

Limestone- This is a soft sedimentary rock of organo-chemical or organic origin, consisting mainly of calcite (calcium carbonate) and often containing impurities of quartz, silicon, phosphate, sand and clay particles, as well as the remains of calcareous skeletons of microorganisms. Most often it has a white, yellowish, light gray or light beige color, less often it is pinkish. White-yellow and white-pink limestone is considered the most valuable. According to their structure, limestones are divided into marble-like, dense and porous. Given that limestone is one of the most budget options when choosing a natural stone, ordering products from it is an excellent solution to a commercial issue.

Marble rocks are an intermediate link between limestone and marble, and are used in the construction of buildings and the creation of sculptures.

dense rocks are widely used for the manufacture of facing slabs (used for exterior and interior cladding of buildings). Such a stone has been popular since ancient times; even the ancient Egyptian pyramids are covered with a thick layer of limestone. In our country, it was often used for the construction of temples. Often there are also frost-resistant varieties of durable rock, which allowed ancient structures to survive to our times, retaining their appearance almost unchanged.

Porous limestones have several types, differing from each other in the degree and nature of granularity: oolitic, pizolitic, shelly, calcareous tuff and others. Oolitic rocks consist of small balls, in the center of each of which there is a grain of sand, a fragment of a shell, or other foreign material. Larger balls are called pisolite limestone. Shell rock is a collection of small fragments of shells. Some varieties of shells are considered a decorative material, they can be easily processed and even polished. Shell rock, consisting of microscopic shells, is called chalk. Porous rocks are used as construction material for the construction of walls, as well as for internal and external cladding of buildings. Very porous deposits are called calcareous tuff.

Chemical composition of limestone: Chem. the composition of pure limestone is close to that of calcite (CaO 56%, CO2 44.0%). The composition of the carbonate part of the limestone also includes dolomite CaMg (CO3) 2, FeCO3 and MnCO3 (less than 1%), non-carbonate impurities - clay aluminosilicates and silica minerals (opal, chalcedony, quartz), oxides, hydroxides and sulfides of Fe, Ca3 (PO4) 2, CaSO4, org. in-in. Prom. the classification of limestones is based on the ratios of the contents of calcite and the main impurities, dolomite and clayey matter, the number of which can vary continuously up to complete predominance. Limestones are commonly referred to as rocks with a calcite content of at least 50%.

Physical properties of limestone: Main physical properties limestone are plasticity, which allows to give products from it any shape, durability, purity of color, strength, uniformity of structure, as well as high thermal insulation properties. It can be sawn, cut and pricked in any direction, processed on lathe or manually, embodying any architectural idea. This material reacts violently to acidic compounds and dissolves in water. As a result of its decomposition, carbon dioxide is formed.

Density 2700-2900 kg/m3,

Bulk weight:

For shells - about 800 kg / m3

For crystalline limestones up to 2800 kg/m3

Compressive Strength:

For shell rock 0.4 MPa

For crystalline and aphanitic limestone 300 MPa

Water absorption - from 0.1% to 2.1%

Porosity - from 0.5% to 35%

Hardness on the Mohs scale - about 3

Frost resistance for crystalline limestones, 300-400 cycles

Features of limestone formation: The vast majority of these rocks were formed in shallow marine basins (although some of them were also formed in land freshwater reservoirs) and occur in the form of layers and sediments. According to their origin, limestones are divided into organogenic (from organic residues), chemogenic (as a result of calcite precipitation) and detrital (a product of the destruction of other limestones).

Limestone mining: Mining limestone natural stone is carried out in an open way, with the help of special crowbars and hammers that break the top layer of rock, and excavators that lift stone blocks. In Russia quarrying of this natural stone is carried out in the Leningrad, Arkhangelsk, Vologda, Tula, Belgorod, Voronezh regions, in the Moscow region, in the Urals, the Volga region, Krasnodar Territory, in the North Caucasus, in the Urals, in several regions of Eastern Siberia. The limestones of the Myachkovsky horizon (Ryazan region) and Vladimirsky limestone became one of the most common.

Scope of limestone: For 28 centuries BC, the greatest architectural structure of all time was erected on the Left Bank of the Nile - the pyramid of Cheops, for the construction of which 2.5 million m3 of limestone blocks were mined. The pyramid is admired for its colossal size, strict proportions and the high perfection of the work of the ancient builders. It has a height of 147 m.

In Europe, white stone (limestone and sandstone) began to be used for the construction of religious and civil structures by the ancient Greeks and Romans, starting from the 5th-7th centuries BC (the first Athenian Acropolis was built in the 6th century BC).

Products made of natural limestone facing stone are used for the construction of buildings and structures and their cladding, are used in the manufacture of platbands, columns, fireplace portals and other decorative elements, are indispensable for interior decoration of floors and walls, door and window openings, including in rooms with high humidity (bathrooms, swimming pools). Such products are used in landscape design in the design of paths, fountains, patios, decorative walls and other garden objects, as well as for the design of fences and the construction of alpine slides (retains heat, passes water and air, normalizes the soil composition). Shell rock and tiles from it are used for exterior and interior decoration of premises (apartments, restaurants, offices, saunas), as well as for the manufacture of decorative architectural elements, lining of fireplaces and stoves. It is the only material that has 100% radiation protection. Limestone is one of the most durable flooring solutions and is ideal for use in kitchens and bathrooms as it is waterproof and does not become slippery when wet. In recent years, the use of limestone floor tiles has grown in popularity. In addition to floors, limestone can also be used for many other surfaces. Limestone is commonly used as a countertop for kitchen countertops, bar counters, window sills, façade cladding, interior wall cladding, landscaping, swimming pools and to create stunning staircases.

LIMESTONE, sedimentary rock composed mainly of calcium carbonate - calcite. Due to its wide distribution, ease of processing and chemical properties, limestone is mined and used in more than other rocks, second only to sand and gravel deposits. Limestones come in many colors, including black, but the most common rocks are white, gray or brownish. Bulk density 2.2–2.7. This is a soft breed, easily scratched by a knife blade. Limestones boil violently when exposed to dilute acid. In accordance with their sedimentary origin, they have a layered structure. Pure limestone consists only of calcite (rarely with a small amount of another form of calcium carbonate - aragonite). There are also impurities. The double carbonate of calcium and magnesium - dolomite - is usually found in variable amounts, and all transitions between limestone, dolomitic limestone and dolomite rock are possible. In the process of limestone deposition, clay particles are also introduced by water, the rock becomes clayey, and clear boundaries between limestone, clayey limestone and shale are erased. Flint is also a common impurity; it is often present in the form of nodules (siliceous nodules) or in the form of more or less pronounced layers. During metamorphism, as the recrystallization of calcite covers the entire rock and a mosaic structure arises (an aggregate of clearly defined isometric grains of approximately the same size that are closely adjacent to each other), limestone gradually turns into marble.

There are many varieties of limestone. Shell rock is the name given to accumulations of fragments of shells cemented into a cellular aggregate. If the shells are microscopic in size, a loosely bound, soft, finely crumbling, smearing rock is formed - chalk. Oolitic limestone consists of small balls, the size of fish eggs, cemented together. The core of each such ball-oolite can be represented by a grain of sand, a fragment of a shell, or a particle of some other foreign material. If the balls are larger, the size of a pea, they are called pisolites, and the rock is called pisolite limestone. Travertine is limestone formed on the surface as a result of the precipitation of calcium carbonate (calcite or aragonite) from water from carbonic sources. If such deposits are highly porous (spongy), they are called calcareous tuff. Marl is a non-cemented mixture of calcium carbonate and clay. The names of some varieties of limestone are due to the possible direction of its practical use. For example, lithographic limestone is an exceptionally dense, compact and uniform stone used in lithography.

Although limestones can form in any freshwater or marine environment, the vast majority of these rocks are of marine origin. Sometimes they precipitate, like salt and gypsum, from the water of evaporating lakes and sea lagoons, but, apparently, most of the limestones were deposited in seas that did not experience intensive drying. In all likelihood, the formation of most limestones began with the extraction of calcium carbonate from sea water by living organisms (to build shells and skeletons). These remains of dead organisms accumulate in abundance on the seafloor. by the most a prime example coral reefs serve as accumulations of calcium carbonate. In some cases, individual shells are distinguishable and recognizable in limestone. As a result of wave-surf activity and under the influence of sea currents, reefs are destroyed. Calcium carbonate is added to the calcareous debris on the seabed, which precipitates from water saturated with it. The formation of younger limestones also involves calcite coming from the destroyed older limestones.

Limestones are found on almost all continents, with the exception of Australia. They were formed in different geological epochs. The thickness of the seams varies from a few centimeters to hundreds of meters. Limestones are common in the United States and occupy 75% of the country's area. In Russia, limestones are common in the central regions of the European part, and are also common in the Caucasus, the Urals, and Siberia.

Limestones (in the broadest sense) have extremely diverse applications. They are used in the form of lump limestone, crushed stone, piece (saw, wall) and rubble stone, facing slabs, mineral chips, crushed sand, mineral powder, mineral wool, limestone flour. The main consumers are the cement industry (limestone, chalk and marl), construction (obtaining construction lime, concrete, plaster, mortar; masonry of walls and foundations; decorative cladding, etc.), road and railway construction, stone riprap for protecting coasts and hydraulic structures, metallurgy (limestone and dolomite - fluxes and refractories, processing of nepheline ores into alumina, cement and soda), Agriculture(limestone flour in agricultural technology and animal husbandry), oil and coke, food (especially sugar), pulp and paper, glass (limestone, chalk, dolomite), leather (limestone), rubber, cable, paint and varnish industry (chalk as a filler). Other applications are polishing of non-ferrous metals and mother-of-pearl (limestone), electric welding (chalk for electrode coating), writing chalks (chalk), thermal insulation building structures And technological equipment(mineral wool), etc.

In Russia, limestone is mined in quarries in the Moscow region, Leningrad (facing), Arkhangelsk, Vologda, Tula, Belgorod, Voronezh regions, in the Urals (Perm region) and the Volga region, the Krasnodar Territory, in the North Caucasus, in the Urals, in a number of regions of Eastern Siberia. Temples and other buildings of white-stone Moscow were erected from limestones near Moscow. Raw materials of carbonate raw materials (limestone, chalk, marl, dolomite) in the country are practically inexhaustible, although they are distributed very unevenly. The largest limestone and dolomite deposits in Europe are located in the Donetsk region in Ukraine.