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 to a greater extent 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. The most striking example of the accumulation of calcium carbonate are coral reefs. 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, protection of shores 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 chemical, food (especially sugar), pulp - paper, glass (limestone, chalk, dolomite), leather (limestone), rubber, cable, paint and varnish industries (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 of 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.
Composition of limestone
The chemical composition of pure limestones is close to calcite, where CaO is 56% and CO 2 is 44%. Limestone in some cases includes impurities of clay minerals, dolomite, quartz, less often gypsum, pyrite and organic residues, which determine the name of limestones. Dolomitized limestone contains from 4 to 17% MgO, marl limestone - from 6 to 21% SiO 2 +R 2 O 3. Limestone is sandy and silicified and has impurities of quartz, opal and chalcedony. It is customary to reflect in the name of limestone also the predominant presence of organogenic remains (bryozoan, algal), or its structure (crystalline, clotted, detritus), or the shape of rock-forming particles (oolitic, brecciated).
Description and types
According to the structure, limestones are crystalline, organogenic-detrital, detrital-crystalline (mixed structure) and sinter (travertine). Among crystalline limestones, according to the size of the grains, coarse-grained, fine-crystalline and cryptocrystalline (aphanite) are distinguished, according to the brilliance at the break - recrystallized (marble-like) and cavernous (travertine). Crystalline limestone - massive and dense, slightly porous; travertine - cavernous and highly porous. Among organogenic detrital limestone, depending on the composition and size of the particles, the following are distinguished: reef limestone; shell limestone (), consisting mainly of whole or crushed shells, bonded with carbonate, clay or other natural cement; detritus limestone composed of shell fragments and other organogenic fragments cemented with calcite cement; algal limestone. White (so-called writing) also belongs to organogenic-clastic limestones. Organogenic-detrital limestones are characterized by a large, low volumetric mass and are easily processed (sawed and polished). Detrital-crystalline limestone consists of carbonate limestone of various shapes and sizes (lumps, clots and nodules of fine-grained calcite), with the inclusion of individual grains and fragments of various rocks and minerals, flint lenses. Sometimes limestone is composed of oolitic grains, the cores of which are represented by fragments of quartz and flint. They are characterized by small pores of various shapes, variable bulk density, low strength and high water absorption. Sintered limestone (travertine, calcareous tuff) consists of sintered calcite. It is characterized by cellularity, low bulk density, easy processing and sawing.
According to the macrotexture and conditions of occurrence among limestones, massive, horizontally and obliquely layered, thick and thin platy, cavernous, fissured, spotty, lumpy, reef, fungal, stylolite, underwater landslide, etc. are distinguished. Organogenic (biogenic), chemogenic, clastic and mixed limestones. Organogenic (biogenic) limestones are accumulations of carbonate remains or entire skeletal forms of marine, less often freshwater organisms, with a small admixture of predominantly carbonate cement. Chemogenic limestones arise as a result of lime precipitation followed by recrystallization of the carbonate mass of sediments, mainly from sea water (crystalline limestone) or from mineralized deposits (travertine). Clastic limestones are formed as a result of fragmentation, washout and redeposition of angularly rounded fragments of carbonate and other rocks and skeletal remains, mainly in marine basins and on coasts. Limestones of mixed origin are a complex of deposits resulting from the successive or parallel overlay various processes formation of carbonate sediments.
The color of limestones is predominantly white, light gray, yellowish; the presence of organic, ferruginous, manganese and other impurities causes a dark gray, black, brown, reddish and greenish color.
Limestone is one of the most widespread sedimentary rocks; she composes various forms relief of the Earth. Limestone deposits are found among deposits of all geological systems - from Precambrian to Quaternary; the most intensive formation of limestones occurred in the Silurian, Carboniferous, Jurassic and Upper Cretaceous; make up 19-22% of the total mass of sedimentary rocks. The thickness of limestone strata is extremely variable: from a few centimeters (in separate layers of sediments) to 5000 m.
Limestone properties
The physical and mechanical properties of limestones are extremely heterogeneous, but are directly dependent on their structure and texture. The density of limestones is 2700-2900 kg/m 3 and varies depending on the content of impurities of dolomite, quartz and other minerals. The bulk mass of limestones varies from 800 kg/m 3 (for shell rocks and travertine) to 2800 kg/m 3 (for crystalline limestones). The compressive strength of limestones ranges from 0.4 MPa (for shell rock) to 300 MPa (for crystalline and aphanitic limestone). When wet, the strength of limestones often decreases. Most of the deposits are characterized by the presence of limestone, not uniform in strength. Losses for wear, abrasion and crushability increase, as a rule, with a decrease in the volumetric mass of limestones. Frost resistance for crystalline limestones reaches 300-400 cycles, but it changes dramatically in limestones of a different structure and depends on the shape and connection of pores and cracks in it. The workability of limestones is directly related to their structure and texture. Shell rock and porous limestones are easily sawn and hewn; crystalline limestones are well polished.
Application of limestone
Limestone has a universal application in industry, agriculture and construction. In metallurgy, limestone serves as a flux. In the production of lime and cement, limestone is the main component. Limestone is used in the chemical and food industries: as an auxiliary material in the production of soda, calcium carbide, mineral fertilizers, glass, sugar, paper. It is used in the purification of petroleum products, dry distillation of coal, in the manufacture of paints, putties, rubber, plastics, soaps, medicines, mineral wool, for cleaning fabrics and treating leather, liming soils.
Limestone is the most important building material, it is used to make facing
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.
The coral reefs formed on the seabed are constantly affected by the sea current, waves and surf, under the intense force of which the existing reefs are destroyed. 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 a huge number of varieties, classified by color, composition and origin, as well as by 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 may have various meanings. 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 history of many millions of years of origin, has high level 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, low 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.
Physiochemical properties
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.
Application natural material maybe in 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 of 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 building material during its operation, it is necessary to without fail take note of its aforementioned characteristics.
what is limestone mineral everything about limestone what it consists of where it is mined!!!
Calcium carbonate, which is part of limestone, is able to slowly dissolve in water, and also decompose into carbon dioxide and the corresponding bases. The first process is the most important factor in the formation of karst, the second, occurring at great depths under the influence of the deep heat of the Earth, dates the source of gas for mineral waters.
Limestone is a widespread sedimentary rock formed with the participation of living organisms in marine basins. This is a monomineral rock, consisting of calcite with impurities. The name of the limestone variety reflects the presence in nm of the remains of rock-forming organisms, the area of distribution, the structure (for example, oolitic limestones), impurities (ferruginous), the nature of occurrence (platystone), geological age (Triassic).
Whole mountain ranges are composed of limestone in the Alps, in the Crimea, and are also widespread in other places. Limestone has no sheen, it is usually light gray in color, but may be white or dark, almost black; bluish, yellowish or pink, depending on the composition of impurities. In limestone there are remains of skeletons of ancient animals.
Limestone is widely used as a building material, fine-grained varieties are used to create sculptures.
Calcining limestone dates quicklime is an ancient binder, still used in construction 1. One of the main building materials, obtained from limestone, is crushed limestone, which is widely used in road construction and in the production of concrete. In metallurgy, limestone is used as a flux.
- Limestone is a sedimentary rock of organic, rarely chemogenic origin, consisting mainly of calcium carbonate (CaCO3) in the form of calcite crystals of various sizes.
Limestone, consisting mainly of the shells of marine animals and their fragments, is called shell rock. In addition, there are nummulite, bryozoan and marble-like limestones, massively layered and thinly layered. During metamorphism, limestone recrystallizes and forms marble.
Calcium carbonate, which is part of limestone, is able to slowly dissolve in water, and also decompose into carbon dioxide and the corresponding bases. The first process is the most important factor in the formation of karst, the second, occurring at great depths under the influence of the deep heat of the Earth, which is a source of gas for mineral waters, absorbs water well. Limestone is widely used as a building material, fine-grained varieties are used to create sculptures.
Calcination of limestone dates quicklime is an ancient binder material used in construction until now. One of the main building materials derived from limestone is crushed limestone, which is widely used in road construction and concrete production. In metallurgy, limestone is used as a flux.
- Limestone is a soft rock that is widely used in construction.
Most often, the rock is mined by blasting, as a result of which limestone turns into crumbs.
Then this mass is lifted from the quarry by an excavator and transported to the factories.
Currently, other methods are being introduced into practice that make it possible to loosen the rock without producing an explosion.
Caterpillar has developed new heavy-duty excavators equipped with special attachments that break rock quickly. There are excavators with both mechanical and hydraulic aerating machines.
The device is attached to the handle with a special mount. And it is quick release. An excavator driver can change the bucket for a baking powder in a matter of seconds, which turns the rock into crumbs.
Then the removable device is changed to a bucket, with which the loosened rock is transported from the quarry. This machine is capable of crushing both soft and fairly hard limestone.
The advantage of this method is also the fact that it makes it possible already in the quarry to carry out rock selection for various fractions. Although it is possible to accurately select a mining method only after analyzing the rock, one can still immediately say that this method is the future.
In Germany, it is used when limestone deposits are located in places with a high population density. The method also pays off when it comes to the impact of production on environment, as it reduces the share of harmful emissions into the atmosphere.
The method is actively promoted Russian company Zeppellin, which uses RipLoad technology for non-explosive limestone mining. The company studies physical and Chemical properties rock limestone at the enterprises where it is delivered.
As a result, data were obtained on which methods should be applied in various fields.
The third extraction method is performed by a milling machine. With this method, the rock is mechanically converted into crumb. Grinding, loading and transportation are carried out simultaneously.
The lowest costs for the extraction of rock are achieved by using an excavator and a hydraulic opener. An even more economical way is to use a mining machine, whose operating costs are 7% lower than mining with an excavator.
- ATP class helped out a lot
Limestone is a rock formed as a result of the deposition of particles of an organogenic and chemogenic nature. Deposits of mineral raw materials used in various industries are distributed over vast territories.
Characteristics of the mineral composition of the rock
In the table of Mohs hardness values, limestone takes 3rd place as the values increase. Its hardness corresponds to 3, and the density depends on the content of impurities, including dolomite, quartz and other minerals.
Substances included in the chemical composition of limestone can be destroyed by the action of water, slowly decompose to the corresponding bases with the release of carbon dioxide. These natural processes are sources of gas for mineral waters and factors contributing to the formation of karst caves in the depths of the earth.
When the temperature gradient rises to 200°C, the stone quickly decomposes, and lime is formed as a result of firing.
The formula for limestone, which is composed of calcite, is CaCO3. If the composition contains dolomite, then the chemical formula includes magnesium CaMg(CO3)2. Limestone rock, the composition of which is formed by shells and their fragments, is called shell rock (shell rock).
The color of the mineral is usually white or gray, but impurities organic matter change the breed, introducing black and dark gray shades. The presence of iron compounds in different concentrations gives yellow, red or brown color.
Breed types
The physical properties of limestone material depend on the presence of voids and pores in the rock. Deposits of mineral raw materials are found in all geological systems.
The most intensive formation of deposits is in the Carboniferous and Cretaceous. The main characteristic of limestone from carbon is the lack of luster and white color with a yellowish tinge. Its distinguishing feature is ease of processing, a variety of textured surfaces and natural patterns.
The structure of the mineral is diverse and serves as the basis for the selection of rock varieties. There are such types:
- organogenic-detrital;
- crystalline;
- mixed (detrital-crystalline);
- travertine (sintered).
According to the size of the grains, coarse, fine and cryptocrystalline types of limestones are distinguished.
The material used as a writing tool for drawing contours on fabric in order to develop a creative bias in children, better known as chalk (white limestone), belongs to the type of organogenic-clastic formations. If you look at a piece of chalk under magnification, you can see small shells in it.
The thickness of the rock strata depends on the conditions of formation of sedimentary formations and ranges from a few centimeters to 5 km. The strength of limestone is low, and in the wet state it decreases.
Each deposit is characterized by an uneven indicator of the strength of raw materials. Marble limestone, unlike other mineral formations, including granite, has a lower hardness and is easy to process.
The properties of a mineral depend on the nature of its formation and composition. Sometimes the rock is composed of oolitic grains, fragments of quartz and silicon, is characterized by small pores, low strength.
So, for example, travertine (sinter formation) is characterized by a structure in the form of cells, a low bulk density; it is easy to process.
A typical example of carbonate formations in modern conditions observed near springs, in the waters of which the dissolved component settles on plants and various objects in the form of plaque.
Putilov limestone used to be the main material for the construction of the city on the Neva. Excellent physical and chemical properties, mineral composition and resistance to environmental influences make it possible to actively introduce it into construction as a decorative cost-effective material.
Marbled limestone consists of carbonates, it contains fossils in the form of mollusks, shells. The extracted material is grayish-blue, white with a yellow tint. Marble limestone rock is used as a finishing component for facades during restoration work.
Scope of application of mineral raw materials
The rock is not rare, deposits are being developed all over the world. Dolomite reserves in the territory of the Russian Federation are unevenly distributed, and the main deposits of raw materials are concentrated in the Central Federal District, the Urals and Siberia.
Depending on the forms of occurrence of the rock and the depth of development, limestone is mined using special equipment that differs in functionality.
The material is used in various industries industrial production, metallurgy. Limestone is used in construction as:
- raw blocks of stone;
- crushed stone;
- lime (white);
- facing plates;
- mineral chips and sand;
- wall stone;
- mineral wool and powder;
- flour.
The cement industry uses varieties of mineral raw materials - chalk and marl. The use of the material in construction as a component for mortars, concrete, plaster improves the quality and reliability of work.
The special properties of carbonate formations make them an attractive material for decorative and finishing works. A variety of textural and textural characteristics serves as a decoration for any interior.
Carbonate material (alabaster, gypsum) is an ornamental stone. For centuries, it has been used to make figurines, candlesticks, and jewelry. Products that have come down to our times are in demand among collectors and connoisseurs of art.
Flux limestone and dolomite are used in metallurgy as a material and raw material for the processing of nepheline ores into cement, soda and alumina. Lime stone is used as a material for the construction of hydraulic structures.
The fluxing additive of the component, introduced into the blast-furnace charge in order to reduce the melting point of the rock that does not contain the ore component, is the only type of the main additive. In metallurgy, dolomitic limestone is used, which increases the content of magnesium oxide in the slag, which increases the mobility and stability of chemical and physical properties material when changing the temperature gradient.
The production of a used compound, which changed the requirements for flux properties, made it possible to work with fragile materials. Therefore, shell rock is used as a charge. Its structure (large porosity) makes it possible to improve technological process and the quality of the material, and the chemical composition has a positive effect on the preservation of temperature conditions.
The use of limestone in agricultural production (dolomite flour) can reduce soil acidity and increase crop yields. The rock is used as a raw material in the glass industry.
The limestone component is used for cleaning sugar from impurities, polishing non-ferrous metal products, external coating of electrodes and thermal insulation of structural joints.
