Hello, our dear readers! Have you ever wondered what diamond and graphite might have in common? It would seem that a diamond is what expensive jewelry is made from, pleasing the eye of a person even with the most refined taste. Hard, tough and virtually indestructible. And graphite, the main element for making pencils, is very fragile and breaks easily. Remember how often your stylus broke?

However, both minerals are related to each other. Moreover, recreating special conditions makes it possible to carry out the process of transformation from graphite to diamond, and vice versa.

Reading the article will allow you to find out what properties the minerals presented in the article have, how they appeared on Earth in the first place, and where you need to go in order to mine diamonds. Or, if you’re less lucky, graphite, and also, is it possible to make diamonds and graphite at home?

We wish you pleasant reading!

Features of diamond and graphite

The main distinctive features of a diamond are:

• the ability to refract and reflect sunlight, which gives it its famous shine;
• the highest hardness (compared to other minerals) and fragility;
• metastability – the ability not to change its structure and state for hundreds of years under normal conditions;
• high thermal conductivity;
• high resistance to acids and alkalis;
• has a low coefficient of friction;
• dielectric, does not conduct electric current.

Such properties of the mineral become possible due to the fact that its internal structure has a complex crystal lattice, which is a cube or tetrahedron. The structure is based on the chemical element carbon.

If there are impurities in its crystal lattice, it can change its color, which is familiar to everyone. Thus, the presence of iron in the composition gives the mineral a brown tint, lithium - yellow, aluminum - blue, manganese - pink or red (depending on the concentration), boron - blue, chromium - green.

Graphite is the exact opposite of diamond. Its structure consists of a number of layers that externally resemble thin plates. The main structural element is carbon. It has a black color with a hint of metal. Soft and slightly oily to the touch.

Has the following distinctive features:

• does not transmit or refract light;
• good thermal conductivity;
• good fire resistance ability;
• fragility;
• low friction coefficient;
• conducts electric current;
• can be mixed with other substances.

Despite such different properties, modern science has learned to artificially produce the minerals presented here from each other.

Is diamond a mineral or not?

In order to answer this question, let’s figure out what a “mineral” actually is. In modern science, a mineral is considered to be a solid body of natural origin that has a crystalline structure, that is, the arrangement of atoms is strictly ordered.

Since the structure of diamond is a cube or tetrahedron and has a clear crystal lattice, it can confidently be classified as a mineral.

The situation is similar with graphite, the lamellar structure of which also has a strict order.

Origin of diamonds and graphite

There is no exact and reliable data on where these minerals came from. There are only some hypotheses, namely:

1. Hypothesis of igneous origin
2. Mantle origin hypothesis
3. Fluid origin hypothesis

The first two theories are the most popular and boil down to the fact that the appearance occurred in the depths of our Earth many millions of years ago at a depth of one hundred to two hundred kilometers. Crystals were brought to the surface as a result of explosions and volcanic eruptions.

Graphite, in turn, can also be formed as a result of changes in sedimentary rocks.

An interesting fact is the presence of diamond chips in meteorites. This suggests that in addition to terrestrial origin, there are also crystals of meteorite origin brought from space.

There are a number of hypotheses about how crumbs could form in meteorites. The most popular theory is that the meteorite itself does not contain diamond chips in a “pure” form, but is only enriched with carbon. Upon impact with the Earth, ideal conditions develop for the recreation of the mineral: high temperature (two to three thousand degrees) and pressure (from 5 to 10 GPa). Diamonds formed by this method are called impactites.

Unfortunately, crystals of cosmic origin are too small for industrial mining and therefore all deposits used for mining are only of natural origin.

Main deposits

The largest diamond deposits are located in the Indian Republic, Russian Federation, Kimberley Province (accounting for 80% of all production).

Russian deposits are located in the Republic of Sakha (Yakutia), Perm Territory and Arkhangelsk Region.

X-rays are used to detect diamond deposits. The search takes decades. A very small number of discovered deposits contain minerals of high quality, sufficient for use in the jewelry industry.

The mining process involves extracting ore and crushing it, separating accompanying rocks. After this, using special equipment, the categories and classes of the extracted material are determined.

The largest graphite deposits are located in the Krasnodar region and Ukraine. Deposits with low quality material are located in Madagascar, Brazil, Canada and Mexico.

As a rule, it is found together with limestone rocks, such as apatite and phlogopite, as well as in pneumatolite formations, namely: quartz, feldspar, biotite, titanomagnetite.

Scope of application

Used in many areas of industry.

• electrical engineering;
• radio electronics and power electronics;
• drilling rigs;
• production of precious jewelry and accessories.

Scope of graphite application:

• creation of fire-resistant equipment;
• production of lubricants;
• production of pencil leads;
• nuclear energy (as a neutron moderator);
• artificial production of diamonds.

The most popular area of ​​application is jewelry making. The processed mineral, called a diamond, has a high value and is very popular in the jewelry market. For many people, it is still an excellent investment option.

Technology for producing diamonds from graphite

For modern science, it is a mere trifle to grow an artificial diamond crystal. If under natural conditions it takes hundreds of millions of years to form, in a specially equipped laboratory this is carried out in much less time.

The principle of unnatural production is to recreate optimal conditions that are most favorable for changing the form of carbon. Both high temperature (from 1500 to 3000 degrees) and pressure (several GPa) are required. The easiest way to obtain it is to pulse heat graphite to two thousand degrees. By maintaining high pressure, the process of converting graphite into diamonds takes place. At the same time, when the pressure decreases, the reverse process starts, in which one mineral turns into another.

In this regard, to obtain a diamond crystal, it is necessary to stably maintain high temperature and pressure parameters for a long time. This makes the conversion technology energy-intensive and costly. In addition, this process produces only industrial diamond, which is unsuitable for use in jewelry.

For these reasons, unnatural diamond production is considered unprofitable compared to mining.

Preparation of artificial graphite

There are the following types of artificial graphites: blast furnace, coke, retort, Acheson.

The most popular unnatural type is coke. The production method involves obtaining a dense carbon mass from sand and coke, firing it, associated with carbonization. At the last stage, crystallization (graphitization) occurs. To reduce porosity, the resulting mineral is impregnated with synthetic resins and roasting is repeated. Each repeated cycle significantly reduces porosity. There can be up to five cycles in total.

A significant disadvantage of artificial graphite is the content of various impurities and, accordingly, low “purity”.

That's all! Thank you very much for your interest and attention! Don't forget to recommend this article to your friends on social networks!

Team LyubiKamni

Bakaeva Anastasia

It all started with a simple pencil! Or rather, from its core. In physics class we covered the topic “Structure of solid, liquid and gaseous bodies,” and it turned out that carbon, graphite and diamond are “relatives.” But how can it be, because carbon is a gas, and graphite and diamond are solid substances with crystal lattices, but graphite “writes,” and diamond is so hard that it can cut glass and metals, and decorate jewelry! We became interested. It turns out that the core (lead) of a simple pencil is a specially processed mixture of graphite, clay, and wax. When we draw, the graphite crystal lattice separates and its atoms lie on the surface in hexagonal planes, and graphite is not included in colored pencils! Just for reference, I will give the approximate composition of a colored pencil: Organic dye plasticizer (stearin, for example, from which candles are made) talc (by the way, the softest mineral on the Mohs scale) kaolin (white clay, it is used in the production of porcelain and also in cosmetics ) CMC glue (CarboxyMethyl Cellulose) is the binder here. Oh how interesting! We prepared a short message about a pencil, and the teacher suggested expanding this topic and turning it into a research project.

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Municipal educational institution "Secondary school No. 2, Ershov, Saratov region"

Research project

Carbon, graphite, diamond

Bakaeva Anastasia

8 "A" class

head: physics teacher of the first category Filippova E.V.

2015

Introduction

It all started with a simple pencil! Or rather, from its core. In physics class we covered the topic “Structure of solid, liquid and gaseous bodies,” and it turned out that carbon, graphite and diamond are “relatives.” But how can it be, because carbon is a gas, and graphite and diamond are solid substances with crystal lattices, but graphite “writes,” and diamond is so hard that it can cut glass and metals, and decorate jewelry! I became interested. It turns out that the core (lead) of a simple pencil is a specially processed mixture of graphite, clay, and wax. When we draw, the graphite crystal lattice separates and its atoms lie on the surface in hexagonal planes, and inGraphite is not included in colored pencils! Just for reference, I will give the approximate composition of a colored pencil:

• Organic dye
• plasticizer (stearin, for example, from which candles are made)
• talc (by the way, the softest mineral on the Mohs scale)
  kaolin (white clay, it is used in the production of porcelain and also in cosmetics)
• CMC glue (CarboxyMethyl Cellulose) is the binder here.

Oh how interesting!

We prepared a short message about a pencil, and the teacher suggested expanding this topic and turning it into a research project.

Goals of work:

Study the structure and physical properties of carbon, graphite and diamond

Learn about the use of carbon, graphite and diamond in technology, industry, jewelry production and science

Learn about creating artificial diamonds

Tasks

Create visual aids for studying crystalline solids (crystal lattices)

Grow your own crystal of copper sulfate (it also has a crystal lattice, like graphite, diamond and even salt and sugar...)

Historical information.

Graphite, diamond and carbon have been known since ancient times. It has long been known that graphite can be used to mark other materials, and the name “graphite” itself, which comes from the Greek word meaning “to write”, was proposed by A. Werner in 1789. However, the history of graphite is complicated; substances with similar external physical properties were often mistaken for it , such as molybdenite (molybdenum sulfide), at one time considered graphite. Other names for graphite include “black lead,” “carbide iron,” and “silver lead.” In 1779, K. Scheele established that graphite can be oxidized with air to form carbon dioxide. Diamonds first found use in India, and in Brazil gems became commercially important in 1725; deposits in South Africa were discovered in 1867. In the 20th century. The main diamond producers are South Africa, Zaire, Botswana, Namibia, Angola, Sierra Leone, Tanzania and Russia. Man-made diamonds, the technology of which was created in 1970, are produced for industrial purposes.“Carbon occurs in nature both in free and combined states, in very different forms and types. In the free state, carbon is known in at least three forms: coal, graphite and diamond. In the state of compounds, carbon is part of the so-called organic substances, i.e. many substances found in the body of every plant and animal. It is found in the form of carbon dioxide in water and air, and in the form of carbon dioxide salts and organic residues in the soil and mass of the earth's crust. The variety of substances that make up the body of animals and plants is known to everyone. Wax and oil, turpentine and resin, cotton paper and protein, plant cell tissue and animal muscle tissue, tartaric acid and starch - all these and many other substances included in the tissues and juices of plants and animals are carbon compounds. The area of ​​carbon compounds is so large that it constitutes a special branch of chemistry, i.e. chemistry of carbon or, better, hydrocarbon compounds.”

Carbon

Plants extract carbon from carbon dioxide - carbon dioxide - in the atmosphere and use it as building material for roots, stems and leaves. Animals get it by eating these plants. And in the soil it accumulates during the decomposition of the bodies of dead creatures. Of all the forms of pure carbon, the best known, and perhaps the most valuable to humans, is coal. It is approximately 4/5 carbon, with the remainder being hydrogen and other elements. The value of coal stems from the chemical properties of carbon, the main one being that it readily reacts with oxygen. This process occurs when coal is burned in air, releasing a large amount of thermal energy that can be used for a variety of purposes. However, carbon in inanimate nature can be found not only in the form of coal. Two other forms of its existence in its pure form, sharply different from each other, are graphite and diamond. Graphite is very soft and greasy to the touch. It serves as an excellent lubricant for many mechanisms. And, as you know, pencil leads are made from it. In this case, graphite is mixed with clay to reduce its softness. Diamonds, on the other hand, are the hardest substances known to man. They are used to create especially durable cutters, as well as jewelry. Carbon atoms can form bonds with each other and with atoms of other elements. The result is a huge variety of carbon compounds. Carbon is included in the composition of plants and animals (~18%). The carbon cycle in nature includes the biological cycle, the release of CO 2 into the atmosphere during combustionfossil fuel, from volcanic gases, hot mineral springs, from the surface layers of ocean waters, etc. The biological cycle consists of carbon in the form of CO 2 is absorbed from troposphere plants. Then frombiosphere returns togeosphere: with plants, carbon enters the body of animals and humans, and then, during the decay of animal and plant materials, into the soil and in the form of CO 2 - into the atmosphere. In the vapor state and in the form of compounds withnitrogen And hydrogen carbon found in atmosphereSun , planets, it is found in stone and ironmeteorites . Carbon reacts with many elements to form carbides (Carbides are compoundsmetals And non-metals With carbon ). Carbon is widely used in metallurgy. (Metallurgy is a set of interconnected industries and stages of the production process from miningraw materialsbefore the release of finished products -black And non-ferrous metals and them alloys ). Due to the ability of carbon to form polymer chains, there is a huge class of carbon-based compounds, which are much more numerous than inorganic ones, and which are studied byorganic chemistry . Among them are the most extensive groups:hydrocarbons, squirrels , fatsetc. Carbon plays a huge role in human life. Its applications are as varied as this many-sided element itself. Carbon is the basis of all organic substances. Any living organism consists largely of carbon. Carbon is the basis of life. The source of carbon for living organisms is usually carbon dioxide from the atmosphere or water. Through photosynthesis, it enters biological food chains in which living things devour each other or each other's remains and thereby obtain carbon to build their own bodies. The biological cycle of carbon ends either by oxidation and return to the atmosphere, or by burial in the form of coal or oil. Carbon in the form of fossil fuels:coal And hydrocarbons(oil , natural gas ) - one of the most important sourcesenergy for humanity . Carbon in the steel industry is one of the most important components of alloys iron-carbon (production cast iron And steel ). Carbon is part of atmospheric aerosols, as a result of which the regional climate may change and the number of sunny days may decrease. Carbon particles absorb solar radiation, which can cause the Earth's surface to warm. Carbon enters the environment in the form of soot in the exhaust gases of vehicles, when burning coal at thermal power plants (thermal power plants), during open-pit mining of coal, its underground gasification, production of coal concentrates, etc. The carbon concentration above combustion sources is 100-400 μg/m³ , large cities 2.4-15.9 µg/m³, rural areas 0.5 - 0.8 µg/m³. With gas aerosol emissions from nuclear power plants, (6-15) 10 enter the atmosphere 9 Bkg/day carbon dioxidegas. High carbon content in atmospheric aerosols leads to increased morbidity in the population, especiallyupper respiratory tract And lungs . Occupational diseases - mainly anthracosis and dustbronchitis. The maximum one-time carbon content in atmospheric air is 0.15, the daily average is 0.05 mg/m³. The toxic effect of carbon included in protein molecules (especially in DNA andRNA ), is determined by the radiation effect of beta particles and nitrogen recoil nuclei and the transmutation effect - a change in the chemical composition of the molecule as a result of the transformation of a carbon atom into a nitrogen atom.

Graphite

Diamond

For the direct transition of graphite to diamond, even more extreme conditions are required compared to the metal-solvent method. This is due to the great stability of graphite due to the very strong bonds of its atoms.

The results of the first experiments on direct graphite-diamond transformation, performed by P. DeCarlne and J. Jamieson of the Allied Chemical Corporation, were published in 1961.

To create pressure, a high-power explosive was used, with the help of which a temperature of about 1200 ° C and a pressure of about 300,000 atm were maintained for about a millionth of a second (one microsecond). Under these conditions, a certain amount of diamond was found in the graphite sample after the experiment, although in the form of very small particles. The resulting crystallites are comparable in size (100 A = 10 nm, or one hundred thousandth of a millimeter) to the “carbonado” found in meteorites, the formation of which is explained by the influence of a powerful shock wave that occurs when a meteorite hits the earth’s surface.

In 1963, Francis Bundy of General Electric succeeded in directly converting graphite into diamond at static pressures exceeding 130,000 atm. Such pressures were obtained using a modified Belt installation with a larger external surface of the pistons and a smaller displacement. To create such pressures, it was necessary to increase the strength of the power parts of the Installation.

The experiments involved spark heating of a bar of graphite to temperatures above 2000 ° C. Heating was carried out by pulses of electric current, and the temperature required for the formation of diamond was maintained for several milliseconds (thousandths of a second), i.e., significantly longer than in the experiments of De- Carly and Jamison.

The sizes of the newly formed particles were 2-5 times larger than those obtained during shock compression. Both series of experiments provided the necessary parameters for constructing a phase diagram of carbon, graphically showing the temperature and pressure ranges at which diamond, graphite and melt are stable.I

Interesting experiments were carried out by Bundy and J. Kasper, who used single crystals of graphite instead of ttolycrystalline material. The diamond crystals in their first experiments had the usual cubic crystal structure.

De-Carli and Jamieson also drew attention to the fact that transformation into diamond occurs more easily when the graphite particles in the samples have an elongation along the so-called c-axis, i.e., perpendicular to the hexagonal layers. When Bundy and Kasper placed single crystals so that pressure was applied along the c-axis and measured the electrical resistance of the crystals under pressure, they found that the resistance increased when a pressure of 140,000 atm was reached.

This was associated with the transition of graphite into diamond, although when the pressure was removed, the reverse transformation into graphite occurred. However, when this procedure was accompanied by heating the sample to 900 °C and higher, crystallites of a new high-pressure phase were formed, having a hexagonal structure rather than the usual cubic one.

Hexagonal carbon has also been occasionally found in natural samples, especially meteorites. It was named lonsdeplit in honor of Kathleen Lonsdale of the University of London for her great services in the field of crystallography, in particular in the study of diamond.

In 1968 to G. R. Cowan. B. W. Dunnington and A. H. Holtzman from the DuPont de Nemur company were issued a patent for a new process consisting of shock compression of metal blocks, such as iron castings containing small inclusions of graphite (at pressures exceeding 1 million atm. )

The metal, which has less compressibility than graphite, acts as a refrigerator, a very quickly cooling inclusion.

This prevents the diamond formed by the shock wave from reverting back to graphite after the shock wave has passed through, a tendency that is typical for experiments with single crystals under cold compression. The final product obtained using this technology is partly hexagonal carbon, which also confirms the tendency for lonsdaleite to form under conditions of very high pressures and relatively low temperatures. The material produced in this way is used as grinding powder.

From time to time, studies aimed at modifying one or another of these methods are reported. Thus, L. Trueb used the De-Carli-Jamison principle to create a pressure of 250,000-450,000 atm for 10-30 μs, accompanied by heating after the impact to 1100 ° C. Graphite was used in the form of particles with a diameter of 0.5-5 microns, and the resulting diamonds had the same dimensions.

However, it has been established that these particles are formed by very small (from 10-40 to 100-1600 A) cubic diamonds. There are currently no indications that Allied Chemical Corporation's products are being commercialized.

The method developed by this company needs further improvement to compete successfully with the solvent method and the DuPont de Nemur method. A potential advantage of shock compression methods is that explosion is a cheap way to create high pressures.

How is graphite different from diamond?

Both diamond and graphite are modifications of carbon.

Diamond:

Graphite:

However, there are a lot of differences:

1. Diamond is the hardest known substance (10 on the Mohs scale), graphite is one of the softest (1-2).

2. Diamond - crystalline cubic polymorphic modification of native carbon.
density about 3.5 g/cc, the highest refractive index among gemstones (2.417). semiconductor. Large transparent diamond crystals are first class gemstones.

Graphite - the most common and stable polymorphic hexagonal modification of carbon in the earth's crust. layered structure. density approx. 2.2 g/cm3. fireproof, electrically conductive, chemically resistant.

3. The difference is also visible when analyzing the creation of artificial diamonds: the technology for producing artificial diamonds is quite complex. Diamonds are synthesized at a temperature of 1200-2000°C and a pressure of 1000-5000 MPa (50-60 thousand atmospheres) from graphite powder mixed with powdered iron, nickel, and chromium. Diamonds crystallize due to the fact that the melt at high pressures is not saturated with respect to graphite and oversaturated with respect to diamonds.

By the way, graphite can also be obtained artificially: heating anthracite without access to air.

4. Diamonds usually fluoresce in X-rays and ultraviolet rays. Diamonds are transparent to X-rays. this makes diamond identification easier: some glasses and colorless minerals, sometimes similar in appearance, are opaque to x-rays of the same wavelength and intensity.

5. About the crystal lattice:

The difference is visible to the naked eye. R The diamond grid is very durable: carbon atoms are located in it at the sites of two cubic lattices with centered faces, very tightly inserted into one another (a = 3.5595 A).

As for graphite: the bond between atoms is strong, of the covalent type; between layers - weak, residual metal type.

Introduction

The diamond industry of our country is at the stage of development, introducing new technologies for processing minerals.

Found diamond deposits are revealed only by erosion processes. For an explorer, this means that there are many “blind” deposits that do not reach the surface. Their presence can be recognized by the detected local magnetic anomalies, the upper edge of which is located at a depth of hundreds, and if you’re lucky, tens of meters. (A. Portnov).

Based on the above, I can judge the prospects for the development of the diamond industry. That is why I chose the topic - “Diamond and graphite: properties, origin and meaning.”

In my work, I tried to analyze the connection between graphite and diamond. To do this, I compared these substances from several points of view. I reviewed the general characteristics of these minerals, industrial types of their deposits, natural and technical types, development of deposits, areas of application, and the significance of these minerals.

Despite the fact that graphite and diamond are polar in their properties, they are polymorphic modifications of the same chemical element - carbon. Polymorphs, or polymorphs, are substances that have the same chemical composition but a different crystal structure. With the beginning of the synthesis of artificial diamonds, interest in the study and search for polymorphic modifications of carbon has sharply increased. At present, in addition to diamond and graphite, lonsdaleite and chaotite can be considered reliably established. The first in all cases was found only in close intergrowth with diamond and is therefore also called hexagonal diamond, and the second is found in the form of plates alternating with graphite, but located perpendicular to its plane.

Carbon polymorphs: diamond and graphite

The only mineral-forming element of diamond and graphite is carbon. Carbon (C) is a chemical element of group IV of the periodic system of chemical elements of D.I. Mendeleev, atomic number - 6, relative atomic mass - 12.011 (1). Carbon is stable in acids and alkalis and is oxidized only by potassium or sodium dichromate, ferric chloride or aluminum. Carbon has two stable isotopes C (99.89%) and C (0.11%). Data on the isotopic composition of carbon show that it comes from different origins: biogenic, non-biogenic and meteoritic. The variety of carbon compounds, explained by the ability of its atoms to combine with each other and the atoms of other elements in various ways, determines the special position of carbon among other elements.

General characteristics of diamond

The word “diamond” immediately brings to mind secret stories about treasure hunts. Once upon a time, people who hunted for diamonds had no idea that the object of their passion was crystalline carbon, which forms soot, soot and coal. This was first proven by Lavoisier. He experimented with burning diamonds using an incendiary machine assembled specifically for this purpose. It turned out that diamond burns in air at a temperature of about 850-1000*C, leaving no solid residue, like ordinary coal, and in a stream of pure oxygen it burns at a temperature of 720-800*C. When heated to 2000-3000*C without access to oxygen, it turns into graphite (this is explained by the fact that the homeopolar bonds between carbon atoms in diamond are very strong, which causes a very high melting point.

Diamond is a colorless, transparent crystalline substance that refracts light rays extremely strongly.

Carbon atoms in diamond are in a state of sp3 hybridization. In the excited state, the valence electrons in the carbon atoms are paired and four unpaired electrons are formed.

Each carbon atom in diamond is surrounded by four others, located away from it from the center at the vertices of the tetrahedron.

The distance between atoms in tetrahedra is 0.154 nm.

The strength of all connections is the same.

The entire crystal is a single three-dimensional frame.

At 20*C, the density of diamond is 3.1515 g/cm. This explains its exceptional hardness, which varies along the edges and decreases in the sequence: octahedron - rhombic dodecahedron - cube. At the same time, diamond has perfect cleavage (along the octahedron), and its bending and compressive strength is lower than that of other materials, so diamond is fragile, breaks apart with a sharp impact and, when crushed, turns into powder relatively easily. Diamond has maximum hardness. The combination of these two properties allows it to be used for abrasive and other tools operating under significant specific pressure.

The refractive index (2.42) and dispersion (0.063) of diamond far exceed those of other transparent minerals, which, combined with maximum hardness, determines its quality as a gemstone.

Impurities of nitrogen, oxygen, sodium, magnesium, aluminum, silicon, iron, copper and others are found in diamonds, usually in thousandths of a percent.

Diamond is extremely resistant to acids and alkalis, is not wetted by water, but has the ability to adhere to some fat mixtures.

Diamonds are found in nature both in the form of well-defined individual crystals and polycrystalline aggregates. Correctly formed crystals look like polyhedra with flat faces: octahedron, rhombic dodecahedron, cube, and combinations of these shapes. Very often there are numerous stages of growth and dissolution on the facets of diamonds; if they are not visible to the eye, the edges appear curved, spherical, in the shape of an octahedroid, hexahedroid, cuboid, and combinations thereof. The different shapes of crystals are due to their internal structure, the presence and nature of the distribution of defects, as well as physicochemical interaction with the environment surrounding the crystal.

Among the polycrystalline formations, ballas, carbonado and board stand out.

Ballas are spherulite formations with a radial structure. Carbonado - cryptocrystalline aggregates with the size of individual crystals 0.5-50 microns. The board is clear-grained aggregates. Ballas and especially carbonado have the highest hardness of all diamond types.

Fig.1

Fig.2

General characteristics of graphite

Graphite is a gray-black crystalline substance with a metallic luster, greasy to the touch, and is inferior in hardness even to paper.

The structure of graphite is layered, inside the layer the atoms are connected by mixed ionic-covalent bonds, and between the layers by essentially metallic bonds.

Carbon atoms in graphite crystals are in sp2 hybridization. The angles between the bond directions are equal to 120*. The result is a grid consisting of regular hexagons.

When heated without air access, graphite does not undergo any change up to 3700 * C. At the specified temperature, it is expelled without melting.

Graphite crystals are usually thin plates.

Due to its low hardness and very perfect cleavage, graphite easily leaves a mark on paper that is greasy to the touch. These properties of graphite are due to weak bonds between atomic layers. The strength characteristics of these bonds are characterized by the low specific heat of graphite and its high melting point. Due to this, graphite has extremely high fire resistance. In addition, it conducts electricity and heat well, is resistant to many acids and other chemicals, easily mixes with other substances, has a low coefficient of friction, and high lubricity and covering ability. All this led to a unique combination of important properties in one mineral. Therefore, graphite is widely used in industry.

The carbon content in the mineral aggregate and the structure of graphite are the main features that determine quality. Graphite is often called a material that, as a rule, is not only monocrystalline, but also monomineral. They mainly mean aggregate forms of graphite substance, graphite and graphite-containing rocks and enrichment products. In addition to graphite, they always contain impurities (silicates, quartz, pyrite, etc.). The properties of such graphite materials depend not only on the content of graphitic carbon, but also on the size, shape and mutual relationships of graphite crystals, i.e. on the textural and structural characteristics of the material used. Therefore, to assess the properties of graphite materials, it is necessary to take into account both the features of the crystalline structure of graphite and the textural and structural features of their other components.

Fig.3.

In this article:

“For what purposes are diamond and graphite used?” - this question is hardly asked by any of the people who show interest only in the shell of minerals. Indeed, what can connect two substances with such different properties? Diamond is a hard mineral, deposits of which are rare in nature. Graphite is one of the softest minerals; its deposits are found in many parts of the world. It would seem that there is no connection between these substances, but in fact this is not the case - understanding this fact allows us not only to understand where and for what purpose they are used, but also how this is done.

Physical and chemical features

Diamond is a transparent mineral, crystalline in shape. There are diamonds colored red, blue and black. A cut diamond becomes a diamond, its value increases, but this does not affect the properties of the substance.

Relationship “artificial diamond - graphite”

The mineral is an allotropic modification of carbon. It ranks 10 on the Mohs hardness scale and is therefore considered the hardest of all minerals. This is the difference between diamond and graphite, even though they may be derivatives of each other.

Diamond reflects and refracts light better than other minerals. The density of the mineral is 3.4-3.5 g/cm3. The ability to conduct heat fluctuates at 2300 W. The friction coefficient for metal is 0.1, which is explained by the presence of a film of adsorbed gas in diamond. - 4000 degrees Celsius, while it must be subjected to a pressure of 11 GPa.

The process of mineral combustion begins when the air temperature reaches 800-1000 degrees. When pure oxygen participates in the combustion reaction, diamond ignites like propane. During the combustion process, a blue flame appears.

The atoms and molecules of the diamond crystal lattice are interconnected by strong bulk bonds, forming a regular tetrahedron. Each atom in such a tetrahedron is surrounded by other atoms that form the top of the tetrahedrons located nearby. Thus, each of the tetrahedrons is part of all tetrahedrons, which determines the hardness and indestructibility of diamond. Diamond and graphite have different lattice structures.

Unlike diamond, graphite is not a crystal. The mineral is a set of plates of black with a gray tint. The appearance of the mineral resembles steel. Graphitization of graphite occurs in metal alloys containing unstable carbon carbides. When contacting graphite, you feel the presence of fat, but it itself is soft and crumbles easily, leaving black spots.

The mineral is a conductor of heat and electricity. Being a polymorphic modification of carbon, it is similar in many ways. A distinctive feature is the structure of the molecular lattice. The graphite lattice is flat. All graphite atoms are located in one plane, represented by a number of hexagons that have weak bonds with each other. This lattice structure makes the mineral soft and layered, which allows it to be used in various fields of activity.

In addition, this lattice structure makes it possible to transform graphite into diamond. Naturally, such a transformation requires conditions such as temperature and air pressure. The process can be reversed: the transition of diamond to graphite occurs during thermal exposure and pressure.

Applications

Diamond is the hardest of all minerals. It cuts glass, wood, metal, and objects made from substances that are inferior in hardness to diamond. This ability expands areas previously limited exclusively to jewelry making.

Graphite is a soft mineral, but this is precisely what makes it indispensable in industry, architecture and even art.

Diamond

Until the middle of the last century, diamonds were used exclusively as decoration. The stones were processed and used as a substitute for money. It should be noted that the first attempts to shape the diamond were not successful. did not allow the use of objects made of metal, stone, or wood for its processing. In the process of research, it was possible to find out that diamond cutting must be carried out with the same durable substance, that is, the diamond itself. This kind of discovery suggested the possibility of using diamonds in other areas.

Today, diamonds are used in:

1. Construction. The creation of diamond drills has made working with concrete and steel structures easier. Diamonds are an important part of drills, cutting and dismantling tools. The use of minerals prevents the appearance of cracks, which is especially important when laying tunnels, laying pipes, and constructing buildings. Diamond drills and saws cut concrete, steel, granite, marble, and grind crushed stone. In this area, diamond and graphite are not comparable, but again are interrelated.
2. Instrument making. Many devices contain a particle of diamond dust or whole diamonds.
3. Mechanical engineering areas. Diamonds are most often used when turning metal tools.
4. Space area. Creating precise telescopes is impossible without the use of diamond parts.
5. Surgery. The surgeon's main instrument is a scalpel, the thickness and sharpness of which largely determines the success of the operation. Diamond scalpels cope with this task perfectly. The lasers being developed on crystals, the conducting substance of which is diamond, deserve special attention.
6. Telecommunications and electronics. Diamonds are also used to allow signals of different frequencies to travel through one cable. Their use in this area is associated with the ability to withstand high temperatures and voltage surges.
7. Science. The mineral neutralizes the effects of an aggressive environment, which is why it is used as a protective element. Diamond is an integral part of experiments carried out in such areas as quantum physics, optics, and the creation of lasers.
8. Mining. Devices, the main part of which is diamond, are used in drilling mines, extracting oil, coal and gas.

For industrial purposes, diamonds grown exclusively synthetically are used. Real stones are used extremely rarely, despite the fact that graphite and diamond occur in nature.

Graphite

Graphite is used in many industries:

1. Metallurgy. The soft substance of graphite makes it possible to make fireproof crucibles from it and to use it in the coating of foundry molds to prevent casting from burning the earth used for molding.
2. Electronics. Graphite is used to produce electrodes and arc coals.
3. Stationery area. The core of pencils and colored pencils is made of graphite. The mineral is used to make copy paper, black paint, and printing ink.
4. Automotive industry. In its liquid state, the mineral is used when volumetric pressing of car parts is necessary.

Graphite is sometimes used as a lubricant when oil is not possible. Graphite is used to cover the surface of steam boilers, which protects them from scale formation. There are special graphite blocks in nuclear boilers. In addition, the mineral is used in the space industry.

An important area of ​​application for graphite is manufacturing.

Technical progress does not stand still; the areas of application of diamond and graphite are expanding every year, which increases the demand for minerals.