Where are chalk and lime used? Physical properties of chalk and its use

Chalk is a white carbonate sedimentary rock, fine-grained, weakly cemented, soft and crumbly, insoluble in water, of organic (zoogenic) origin. In mineral composition, chalk is close to limestone and is composed mainly of calcite (91-98.5%). The basic chemical composition of chalk is calcium carbonate with a small amount of magnesium carbonate, but a non-carbonate part is usually present, mainly metal oxides. Chalk usually contains an insignificant admixture of tiny grains of quartz and microscopic pseudomorphs of calcite from fossil marine organisms (radiolaria, etc.). Large fossils of the Cretaceous period are often found: belemnites, ammonites, etc. Natural chalk is characterized by the absence of recrystallization and layering, a large number of passages of various mud-eating animals (ground eaters).

The mineral composition of chalk is dominated by calcite, which can be of either biogenic or autogenic origin; organic remains usually make up a significant part of the rock (up to 75%). They are mainly represented by the skeletal shells of planktonic algae-coccolithophores, as well as foraminifera (sometimes up to 40%). The size of the skeletal remains is 5-10 microns. Powdered calcite with particles 0.5-2 microns in size has a variable, but sometimes significant value (10-90%), less significant is the content of larger particles in the form of microscopic calcite crystals. Occasionally in the Cretaceous shells of mollusks, skeletons of bryozoans, inocerams, remains of crinoids, sea urchins and crinoids, flint sponges, and corals are found. In small quantities, usually up to 5, less often up to 10-12%, pelitomorphic non-carbonate impurities are present, mainly of terrigenous, less often autogenous origin: quartz, feldspars, clay minerals (glauconite, kaolinite, hydromicas, montmorillonite), opal, chalcedony, pyrite and etc. Concretions of flint, pyrite and phosphorite are rare and only in places.

In the chalk strata, the development of large sustained cracks is observed - sheet and vertical, filled with chalk flour. At surface outcrops, the network of cracks becomes very dense. When chalk samples are impregnated with oil, hidden vein structures appear in them in the form of intertwining tiny cracks, as well as traces of numerous passages of worms - silt eaters. In all chalk deposits in different areas (horizons), chalk differs both in chemical composition and in physical and mechanical properties.
Density 2690-2720 kg/m3; porosity 44-50%; natural humidity 19-33%. When moistened, the strength of chalk begins to decrease already at a humidity of 1-2%, and at a humidity of 20-30%, the compressive strength increases 2-3 times, and plastic properties appear. Natural chalk has practically no frost resistance; after several cycles of freezing and thawing, it breaks up into separate pieces measuring 1-3 mm.

Based on physical properties and structural characteristics, three types of chalk are distinguished: white chalk; marly, characterized by greater density and less whiteness, which is due to the presence of clay substances; chalk-like limestone is a transitional difference from chalk to limestone.
Finding

Chalk is a semi-hardened silt of warm seas, deposited at a depth of 30 to 500 m. It is widespread in nature and is characteristic of deposits of the upper part of the Cretaceous system and the lower Paleogene, which is associated with the lush development of coccolithophores. Accumulations of white writing chalk are a specific feature of the Late Cretaceous era and are found in almost all stages of the Upper Cretaceous, from the Cenomanian to the Masstrakhtian inclusive. Chalk-like limestones are common in Tertiary deposits; in the Paleozoic, Cretaceous accumulations are not preserved, transforming into various limestones.

The most significant belt of chalk deposits is distributed in Europe, from the Emba River in Western Kazakhstan to Great Britain. Their thickness reaches several hundred meters (in the Kharkov region - 600 m). The thick chalk belt stretches across the entire European continent, including northern France, southern England, Poland, passes through Ukraine, Russia and moves into Asia - Syria and the Libyan Desert. Chalk reserves are distributed unevenly across territories: about 48-50% of reserves of high-quality chalk with a high content of calcium and magnesium carbonate and a minimal content of harmful impurities are concentrated in Russia; about 32-33% in Ukraine and a little more than 12% in Belarus. There are small deposits in Kazakhstan, Lithuania and Georgia. The total balance reserves of chalk in Russia are estimated at 3300 million tons with unlimited forecast reserves.

The reserves of the largest Sebryakovsky (Volgograd region, Russia) chalk deposit for cement production are 890 million tons. Almost unlimited predicted chalk resources are concentrated in the Belgorod region (Russia), where 29 chalk deposits have been explored with total reserves of 1000 million tons, the largest of which which are Lebedinskoye, Stoilenskoye and Logovskoye. At the same time, the Lebedinskoye and Stoilenskoye deposits account for 75% of the explored chalk reserves of the Belgorod region. These two deposits are exploited for the extraction of iron ore, where chalk is the overburden rock. The chalk deposits of the Voronezh region belong to the Turon-Coniacian age. Chalk has a high content (up to 98.5%) and a low content of non-carbonate impurities (less than 2%), enriched in amphora silica, chalk occurs in close proximity to the surface and is covered with chalk eluvium or Quaternary sediments. A characteristic feature of the chalk deposits in the Voronezh region is its water saturation (moisture content reaches 32%, which causes serious difficulties in its extraction and processing).
Practical significance

In industry, chalk is used to produce lime, cement, soda, glass, and school chalk. Used as a filler for rubber, plastics, paper, paints and varnishes. In agriculture it is used for liming soils and feeding animals, in perfumery - for preparing toothpastes and powders. In the paper industry, it was used as a filler and bleach along with kaolin. Chalk is a necessary component of coated paper used in printing for printing high-quality illustrated publications. Ground chalk is widely used as a cheap material for priming, whitewashing, painting the walls of houses, and for protecting tree trunks from sunburn. The use of chalk as a filler and pigment in the production of paper and cardboard can be successful, provided that the requirements for this type of raw material are met in terms of its optical properties and particle size distribution. The quality of chalk is mainly determined by its chemical composition and for many industries is regulated by state and industry standards; GOST 17498-72 "Chalk. Types of grades, basic technical requirements"; GOST 12085-73 "Natural enriched chalk (used in the rubber, cable, paint and polymer industries)"; GOST 8253-79 "Chemically precipitated chalk"; OCT 21-37-78 “Chalk and limestone for mineral feeding of farm animals and poultry”, etc.

The suitability of chalk for the production of lime and cement is determined by semi-factory tests. As of January 1, 1985, the CCCP included 219 chalk deposits with balance reserves explored by industrial categories of 1,680 million tons. In addition, 31 chalk deposits with reserves of 3,534 million tons were included in the balance of reserves of cement raw materials. Chalk reserves account for 12% of all carbonate cement raw materials. The reserves of the largest Sebryakovsky (Volgograd region of the RSFSR) chalk deposit for cement production are 890 million tons. Deposits with chalk reserves of 20 million tons or more are considered large. France, Great Britain, the GDR, and Denmark have large reserves of chalk. In 1984, 75 deposits were developed in the CCCP (all open pit) and 12.4 million tons were produced; in addition, 39.2 million tons were produced from 17 deposits of cement raw materials.

The Zhigulevsky Construction Materials Plant (Kuibyshev Region of the RSFSR) artificially produces chemically precipitated chalk from limestone in the amount of 16.5 thousand tons per year. In the United States, there are chalk deposits only in the central and southern states, but the chalk is of low quality, so the United States imports high-grade chalk from France, Great Britain and Denmark.

Rock Properties

• Rock type: sedimentary rock
• Color: white
• Color 2: White
• Texture 2: homogeneous porous
• Structure 2: fine-grained

Chalk- This is not only a familiar object from school times, but also a witness to eras that passed millions of years ago.

Most of the chalk composition is formed by calcium deposits of the shells of prehistoric microorganisms and protozoan plants. Chalk deposits, including processed ones, are used today in various fields - from the production of paints and food additives to cosmetics.

How did chalk originate?

Chalk is a natural material and is mined as a mineral. It is basically calcium deposits formed from the remains of ancient earthly organisms.

In the production of chalk and chalk-containing products, already processed chalk is used.

Natural chalk deposits often contain various undesirable impurities - stones, sand and various mineral particles. Therefore, chalk extracted from the deposits is broken and mixed with water in such a way as to obtain a suspension.

In this case, heavy impurities sink to the bottom, and light calcium particles are sent to a special tank, where, after adding a special adhesive, they are dried, turning them into chalk with which you can draw.

Raw chalk from chalk quarries is used for construction purposes to produce lime.

We bring to your attention another article about the origin, its composition and medicinal properties.

What is chalk and what does it consist of?

The composition of chalk includes:

• calcium oxide – from 47 to 55%;
• carbon dioxide - up to 43%;
• silicon dioxide – no more than 6%;
• aluminum oxide – up to 4%;
• magnesium oxide – no more than 2% of the total mass of chalk;
• chalk may also contain iron, however, its concentration usually does not exceed 0.5%.

Chalk accumulations

The accumulation of Cretaceous deposits began in the so-called Cretaceous period, covering a period of 80 million years. About 20% of the Earth's sedimentary rocks include chalk.

Chalk deposits:

• To the largest chalk deposits include the White Cliffs of Dover, the chalk caves in the French city of Champagne and the chalk cliffs of Mons Klint in Denmark.
• On Russian territory Cretaceous mountain deposits up to 600 meters thick are located south of Kharkov.
• The largest deposits in the Voronezh region– Kopanishchenskoye, Rossoshanskoye and Buturlinskoye. The city of Belgorod supposedly got its name thanks to local chalk deposits.

Chalk formation

The formation and accumulation of limestone deposits took place over eighty million years.

Foraminifera- single-celled organisms whose shells served as the basis for the formation of today's Cretaceous deposits. After these protozoans died, their shells sank to the ocean floor, creating foraminiferal limestones.

These formations, along with the remains of unicellular coccolithophorid plants, form part of today's Cretaceous accumulations. The remains of coccolithophores and shells of ancient mollusks, compressed under water pressure, were supplemented by skeletal remains of fish and animals for millions of years.

Despite the fact that back in 1953 scientists announced the predominant role of plants in the formation of limestone rocks, there is still an opinion among ordinary people about the primacy of foraminifera.

Compound

The composition of chalk deposits includes:

• Skeleton fragments– approximately 10%. These are the remains of not only protozoa, but also large multicellular animals.
• Ancient mollusk shells- 10 %. Among them were animals with limestone shells - foraminifera.
• Particles of limescale algae growth– no more than 40%. Most of the limestone deposits, contrary to popular belief, were formed from the remains of the simplest plants - coccolithophores, and not thanks to the shells of foraminifers. Coccolithophores have not become extinct; they thrive in the vast oceans today, taking part in the exchange of carbon between the ocean and the atmosphere.
• Ground crystalline calcite– no more than 50%. These are natural mineral formations of complex origin.
• Insoluble silicates- until 3%. These are minerals of geological origin - sand, rock fragments carried into chalk deposits by wind and water. Properties of chalk

Humidity has a great influence on the properties of chalk, affecting its strength and ductility. An increase in humidity leads to deformation, while in a dry environment chalk can crumble even from slight pressure.

Rock saturated with moisture sticks to construction tools. That is why construction work using calcium carbonate is carried out in countries with hot and arid climates. An excellent example of an ancient limestone structure is the Egyptian pyramid of Cheops (Khufu).

At sub-zero temperatures, the rock is prone to disintegrating into fragments of several millimeters.

Chalk cost

The price of chalk will depend primarily on its type (processing) and purpose:

• for painting on asphalt will cost no more 200-400 rubles per package.
• White crayons without dyes will cost about 100 rubles .
• Farmer's chalk I buy in large quantities, shipping several tons. The cost of each ton of ground chalk is 3000-5000 rubles.
• Price for food chalk, used in medicine and in food additives (E-170) – from 40 to 300 rubles for 100 grams. The stone was also used in medicine).

Application of chalk

Today, chalk is a fairly widespread material for various areas of production.

So, chalk is used in the following areas:

1. Chalk paints used for interior decoration during construction and repair work.
2. Chalk is included in cement mixtures, providing them with softness and elasticity.
3. Ground natural chalk actively used for glass production.
4. Chalk is included in farm feed and is used to fertilize the soil.
5. Chalk is the basis for cosmetics– lipstick, foundation, powder, etc. It is the chalk in the foundation that absorbs excess oil and protects the skin from shine.
6. Chalk is also used for household purposes. as an absorbent and whitening component.
7. Production of tooth powders and pastes also cannot do without the use of chalk.
8. In the production of paper and cardboard products Fine (crushed) chalk is used as a filler and paper brightener. Chalk treated with stearic acid has hydrophobic properties. It is also used in the paper industry. The chalk content in paper improves print quality and reduces the likelihood of wear and tear on the printing equipment.
9. Not long ago, chalk was used to mark the playing field.. The spray that rose into the air after the ball hit the line was easy to see. Today, titanium dioxide is used instead of chalk.
10. To remove sweat and reducing the risk of slipping, chalk is still used in sports such as weightlifting, gymnastics and rock climbing today.

Is it possible to eat chalk?

A lack of calcium and other beneficial microelements can lead to a desire to eat chalk. During pregnancy and anemia, some people have a strong craving for eating chalk, so the question of the safety of this mineral for the body arises among many.

Of course, one or two small pieces of pure chalk will not cause much harm to the body. However, it must be remembered that chalk without impurities is not available for free sale and it is practically impossible to get it, except perhaps in a pharmacy in the form of calcium gluconate. The most common product, “school chalk,” is produced with glue and various dyes that are toxic to the body.

Consumption of chalk in large quantities can cause calcification of blood vessels, the formation of kidney stones and provoke problems with the digestive tract.

In addition to the harmful effects of the impurities that make up construction and office chalk, it is characterized by oxidation when interacting with gastric juice, turning it into a harmful chemical reagent.

What to do if you want to eat chalk?

The desire to eat chalk is often a signal of a lack of calcium in the body. The reasons for its deficiency may be a monotonous diet, prolonged stress conditions, weakening of the body after serious illnesses and pregnancy.

Considering that during pregnancy it is calcium that is the basis for the formation of the child’s nervous and skeletal system, the deficiency of this mineral must be replenished. In this case, a varied diet cannot completely solve the problem, so doctors strongly recommend taking special vitamin complexes during pregnancy.

Due to the fact that the neural tube of the fetus is formed in the early stages, in order to minimize the risks of abnormal development, it is necessary to start taking vitamins while planning pregnancy. Anemia and calcium deficiency in the body often appear with heavy and long periods.

For symptoms of severe calcium deficiency (convulsions, noticeable deterioration and pallor of the skin and hair) You can take calcium gluconate tablets. Unlike stationery and other types of industrial chalk, they are safe, however, with prolonged use they can lead to constipation.

As a rule, the craving for eating chalk ends after expanding the diet to include dairy products, chicken eggs and fresh herbs.

In some cases, the desire to eat inedible and inedible substances may be a sign of a mental disorder. The consequences of consuming inedible items are intestinal obstruction and nutritional deficiencies.

Chalk is a soft, white, porous sedimentary rock that is a type of limestone and consists of the mineral calcium (calcite), also called calcium carbonate or CaCO3. It is formed in the depths of the sea with the accumulation of small plates of calcite. Chalk contains a small amount of magnesium carbonate and metal oxides.

Chalk has a very greater resistance to weathering than the clay with which it is usually associated, thus forming the high, steep cliffs where the chalk ridges meet the sea. Chalk hills typically form where strips of chalk reach the surface at an angle, thus forming a cliff. Because chalk is porous, it can hold large amounts of groundwater, providing natural reservoirs that slowly release water due to dry seasons.

1. Clusters
2. Education
3. Compound
4. Used

Chalk accumulations

The Cretaceous group of the European stratigraphic unit occurred during the Cretaceous period. It forms the famous White Cliffs of Dover in Kent (England), as well as the white slopes on the other side of the Strait of Dover. In Champagne (France), chalk caves are used to store wine. Some of the highest chalk cliffs in the world occur in Mons Klint (Denmark).

Chalk formation

Ninety million years ago in northern Europe, silt accumulated at the bottom of a great sea. Protozoa, such as foraminifera, lived on marine debris that fell down from the upper layers of the ocean. Their particles were made of calcite, extracted from sea water.

Chalk composition

Chalk consists mainly of calcium carbonate (more than 98%) with small amounts of silt and clay.

Chalk is used

It is used in the production of quicklime and slaked lime, as a whitewash for buildings and tree trunks. In south-east England, Danehole is a prime example of ancient chalk quarries. In such places, silicon was mined, which was then used in the production of stone tools.

They write with chalk on school boards, mostly rough ones. Although natural chalk is traditionally used, modern chalkboard chalks are typically made from the mineral gypsum (calcium sulfate), often supplied in sticks of compressed powder about 10cm in length.

Sidewalk chalk is similar to school chalk, although it is larger and more colorful. It is used to paint on sidewalks, streets and roads. This is done mainly by both children and adult artists.

In agriculture, chalk is used to increase pH in soils with high acidity. The most common forms are CaCO3 (calcium carbonate) and calcium oxide.

In tennis, chalk was previously used to mark the playing field. This has the advantage that if the ball hits the line, a cloud of chalk or dust pigment can be seen. Currently, chalk has been replaced by titanium dioxide.

In gymnastics, rock climbing, weightlifting and tug of war, chalk - now usually magnesium - is used on the hands to remove sweat and reduce slipping.

Tailor's chalk is hard and is used to make temporary marks on fabrics. Nowadays it is typically made from talc (magnesium silicate).

Toothpaste also usually contains a small amount of chalk to serve as a mild abrasive.

Chalk is used for very fine polishing of metals.

Chalk is a source of quicklime by thermal decomposition or slaked lime by quenching with water.

Sushi according to mineralogy. Scientists have found that carbonate, or simply chalk, mostly consists of coccoliths. This is the name given to algae that produce lime during their life processes.

This changes ideas about animal nature. They were confident in it until 1953. Now, chalk recognized as a breed of plant origin. The remains consist of compressed sea shells.

Both they and algae are components for sushi. Interestingly, chalk is also edible. This has been proven more than once. If there is not enough calcium in the position, it draws to the chalk. Many people ate it, but no one felt it.

Doctors confirm that purified chalk can only bring benefits. It’s not for nothing that calcium carbonate is sold in pharmacies. Let's study the properties of the drug and a complete list of areas of its application. But first, let’s clarify the concept itself.

What is chalk?

So, chalk stone- This is a rock. This means that limestone is composed of several minerals that can exist separately. The basis is calcium carbonate. It is present in the breed up to 98%.

Therefore, chalk is often called calcium carbonate, or, simply, . But the stone also contains carbonate. Among minerals it is listed as . Another fraction of a percent of the chalk composition consists of metal oxides. That is, the rock also has an inorganic component.

The name of the algae that composes the stone is mentioned. Now, let’s determine which animal shells complement plants. Basically, these are foraminifera shells. These are single-celled crustaceans. Not visible to the unarmed.

Foraminifera become noticeable when they sink to the seabed. This happens after the death of single-celled organisms. In part, their shells are complemented by the shells of oysters and other shellfish. Everything is compressed together under water pressure, transforming into rock.

Properties of chalk

Chalk formula does not imply its dissolution in water. Otherwise, rock deposits could not form on the ocean floor. When the waters dry up, the landscape changes, and the chalk moves onto land. This is where it is mined. However, ambient humidity affects mineral. Chalk stronger in dry environments. Changes start already at 2% humidity.

The decrease in strength is accompanied by an increase in ductility. If in a dry environment the chalk crumbles into powder at the slightest pressure, the wet one only becomes deformed. However, working with water-saturated chalk is difficult.

Rock sticks to equipment. Therefore, structures made of calcium carbonate can only be found in hot and arid regions, for example, in. The pyramid of Khufu, considered the oldest building on Earth, is made of limestone there.

Chalk tolerates cold much worse than heat. Having survived sub-zero temperatures, the rock breaks up into pieces of 1-2 millimeters. In some cases this makes it easier use of chalk. We will devote a separate chapter to the question of which ones.

By color white chalk. This is the only natural shade. Colored crayons- colored rock. It can be pressed or lumpy. Food coloring is rarely added to products. Therefore, colorful crayons are toxic to the body.

Since most of the chalk is carbonate, it dissolves in and. The inorganic component, as a rule, remains intact. Traces of chalk in three remained intact.

They reached Earth and were studied. All three came from Mars. The presence of carbonates in the rocks of the planet gave researchers another reason to think that if there is no life on Mars now, then there was once there.

Chalk mining

The chalk of the lower horizons is considered to be of the highest quality. This is the name given to the deep layers of rock. However, they are usually saturated with moisture. Therefore, it is rarely possible to extract from lower horizons. Rock sticks to equipment.

In the upper layers of limestone there is a lack of calcium carbonate. If it is less than 87%, the rock has to be enriched, and this is expensive. Therefore, the Valuiskoye, Znamenskoye and Zaslonovskoye fields are almost not being developed. High-quality chalk is present only in the Belgorod and Voronezh regions. That's where they mine.

Chalk production in low-carbonate deposits it is justified only for construction purposes. In particular, lime of acceptable quality is obtained from unenriched chalk. It is used for reclamation work.

They are carried out during soil deoxidation. Limestone is alkali and can balance the environment. This is where the ability of chalk to disintegrate due to frost comes in handy. There is no need to grind the rock to an acceptable size. It is enough to grind it a little, throw large pieces into the soil, and after frost the material will crumble on its own.

Application of chalk

Whitewashing of premises has become obsolete. It was carried out with chalk solutions. By this we mean liquids with a suspension of undissolved rock particles in them.

But in modern times, chalk paints are in demand. They have an adhesive base and are used only for interior decoration. It is produced on plastered, leveled surfaces.

Cement production cannot do without chalk. Therefore, calcium carbonate can be added to the foundation with the same peace of mind as rubble. Cement became the basis due to its softness, plasticity and, of course, availability. More than 20% of the Earth's sedimentary rocks contain chalk. In the earth's crust it occupies 4% of the volume.

They also add it to chalk. The proportion of limestone is almost equal to the content. We can say that chalk is mixed into the original mixture in equal parts.

In farming, chalk is needed not only for soil deoxidation, but also for the production of animal feed. Why do people eat chalk, but animals can’t? They can, and do, benefit from it.

Chalk in feed is a source of calcium, in other words, a mineral additive to food. With it, animals develop better and do not suffer from fragility

Fine chalk is used in cosmetics. The same is needed in the paper industry. Here the carbonate rock serves as a filler and brightener for the sheets. If they have chalk in them, it's easier to print. In addition, sheets with calcium carbonate are not sensitive to moisture. This extends the service life.

The use of chalk is also due to careful handling of production equipment. Since the material is finely dispersed, its abrasive properties are reduced to zero. Accordingly, friction is minimal, as is equipment wear.

Chalk price

The cost of chalk depends on its purpose and type. So, for 5 patterned chalks for asphalt they ask for 200-450, and for a package of simple chalks - from 10 to 90. Feed chalk is sold, as a rule, not in packages, but in bags. It is customary for farmers to ship in tons. For 1,000 kilograms they charge 3,000-4,000 rubles.

Food chalk is sold in powder or pieces. The goods are packaged in bags and sold in grams. For 0.1 kilo you will have to pay 40-290 rubles. The highest price tags are set for powdered chalk.

By the way, chalk is an official food additive. Calcium carbonate is hidden under the code E-170. This food serves as a stabilizer, that is, it prevents food from clumping. True, in the nomenclature of food additives E-170 refers to dyes. These are systematic flaws that have not yet been corrected.

Modern lifestyle has a huge impact on human health. More and more often you can find people suffering from vitamin deficiency and insufficient amounts of nutrients in the body. This is why food chalk has become very popular lately.

I want chalk, what does that mean?

Many consider the need for chalk to be a very strange phenomenon, abnormal for the average human body.

In everyday life, the desire to chew chalk is usually associated with pregnant women; indeed, they often have such taste preferences. This is due to the fact that during the formation and growth of the fetus, the female body requires double portions of vitamins and microelements.

Particularly important is the adequate amount of calcium that lump chalk contains for meals. It serves as a building material for most tissues, nerve cells, skeleton, cartilage tissue, hair, nails, internal organs and skin of a small person.

However, a lack of calcium can accompany absolutely any person; it is usually characterized by the following symptoms:

• Brittle and dull hair;
• Caries, bone fragility (frequent fractures);
• Brittle nails prone to splitting;
• Dull skin tone;
• Loss of skin elasticity;
• Muscle cramps;

Such conditions are characterized by a pronounced disturbance of calcium metabolism, which natural chalk for food will help to cope with.

What is chalk made of?

The composition of food chalk is a combination of inorganic salts (carbonates). The main element of such compounds is considered to be Ca (calcium). Many are sure that natural lump chalk is nothing more than the carbonate CaCO3, known to everyone from school.

However, an in-depth study of this issue makes it possible to verify that chalk for food includes other elements of the periodic table:

• Of course, calcium oxide takes up almost half of the component composition of the substance. The CaO content in the mineral reaches 55%.
• The second position in the list of components is occupied by carbon dioxide or CO2. Its share in the composition of chalk sometimes reaches 43%.
• The oxide of a metal such as magnesium (MgO) occupies a very small volume, which usually does not exceed 2%.
• The quartz component affects the density of food chalk in direct proportion. The more SiO2 a substance contains, the higher its density. The mass fraction of quartz from the total volume sometimes reaches 6%.
• Al2O3 is quite slightly inferior in volumetric content to quartz inclusions. The total volume of aluminum oxide in limestone corresponds to 4%.

Sometimes you can find natural chalk with a pinkish or even reddish tint. The rock has this feature due to its high content of iron oxides. In ordinary white chalk, the Fe2O3 content does not exceed the threshold of 0.5%.

Where is chalk mined?

Those wishing to compensate for calcium deficiency should know what food chalk is and where it comes from.

There are more than 100 deposits of natural chalk on the territory of the Russian Federation. Among them, three zones stand out in which the concentration of carbonate reserves reaches high levels.

The Volgograd region takes a huge share of this figure; its quarries account for up to 26% of the country's reserves. Lump chalk from these deposits is of excellent quality, it contains a minimal amount of impurities. The number of foreign inclusions does not exceed 2%. However, Volgograd chalk is quite saturated with water; the water content in dry chalk exceeds the specified standards by almost 10-15%. This fact makes it difficult to obtain.

The next position is occupied by the Belgorod region, where up to 24% of chalk reserves are concentrated. The delicious chalk mined here is 99% carbonate, which is an excellent indication of its high quality.

The Saratov region owns an 11% share in the total chalk wealth of the Russian Federation.

Harm and benefits of chalk when eaten

Lump chalk for food is becoming increasingly popular; the harm and benefits of this substance are discussed by experts to this day. It is not possible to clearly evaluate the sedimentary mineral, because it has both negative and positive effects on the human body.

The benefits of natural chalk for food are as follows::

1. Strengthens fragile bones and serves as a preventive measure against caries;
2. Helps maintain healthy and beautiful hair, nails, teeth and skin;
3. In small quantities it helps to improve the functioning of the digestive system;
4. Provides joint mobility and muscle elasticity;
5. Promotes proper functioning of the cardiovascular system;
6. Participates in metabolic processes at the intercellular level;
7. Affects blood clotting and hemoglobin levels (indirectly).

Tasty chalk for food has a negative effect only when there is an excess of it in the body.

Excessive calcium intake leads to the following side effects:

1. Increased blood clotting;
2. Reduced strength of bone tissue and tooth enamel;
3. The emergence of a risk of diseases of the endocrine system;
4. Angina;
5. Decreased muscle tone;
6. The appearance of kidney stones;
7. Increased acidity of gastric juices, which contributes to the development of diseases of the gastrointestinal tract (gastritis and ulcers);
8. Gout;
9. Calcinosis (deposits of Ca salts in the tissues of internal organs).

When discussing the negative consequences of eating chalk, we can conclude that they are caused by the quantity and quality of the mineral consumed.

Which chalk is best for food?

People with a lack of calcium in the body are often interested in where to buy chalk for food and which one is better. They are also studying the question of what is the most delicious chalk for food.

When you want to chew on block chalk, blackboard chalk usually comes to mind. However, this product not only will not bring benefits, but can also cause harm due to the presence of chemical additives in it. Such substances poison the body, the resulting toxins disrupt the functioning of internal organs and spoil health in general.

It has been proven that school crayons dry out the airways by settling on the epithelium of the larynx. They also clog blood vessels, causing liming to occur, which leads to disruptions in the functioning of the cardiovascular system.

The solid particles that this type of chalk contains can scratch the tooth enamel, which will inevitably lead to caries. They act similarly on the oral mucosa, creating microscopic wounds in it that are invisible to the human eye. These cracks are a direct path to the appearance of inflammatory processes and the penetration of infection into the body.

Once in the stomach, school chalk causes a reaction similar to the extinguishing process. This chalk is less tasty compared to its natural counterpart.