What minerals contains diamond. Physical properties of diamond. Astrology about diamonds

Contrary to common misconceptions, diamonds in nature are not at all located throughout the entire surface of the earth's crust. Carbon - a non-metal, which is the basis of this mineral, becomes a diamond only when exposed to extremely high temperatures and pressure at a depth of 160 to 480 km. The "cradle" of the vast majority of crystals are volcanoes, it is thanks to them that diamonds are closer to the surface, so quarrying is carried out in areas with increased volcanic activity. Some of the minerals are simply washed out of the kimberlite pipes.

The origin of diamonds is still unclear, and numerous disputes are still ongoing on this subject. Only one thing was accurately determined - the place and time of their formation. Most scientists agree that diamonds originated in the mantle of our planet between 100 million and 2.5 billion years ago. Carbon at a depth of 200 km under the influence of temperatures of 1300 ° C and at a pressure of 4-5 GPa gradually formed a diamond crystal lattice. Cases of the formation of diamond deposits at a depth of 700 km are known.

The most popular theories according to which diamonds are formed in volcanic rocks:

  1. Carbon got into the solidifying magma as part of hydrocarbons, so diamonds arose in the upper layers of the crust of our planet.
  2. The non-metal crystallized very deeply - at the depth of already ultrabasic rocks, after which the deposits were carried upwards by magma flows.
  3. The last theory is the most popular. Most of the crystals originated in the ultramafic rock, and some diamonds arose already in the process of the ascent of this rock to the surface of the crust.

A real diamond is a non-metal, which is actually not that rare. The reason for its high cost is that only a small number of deposits are available to mankind, while the main deposits are located too deep underground.

DIAMOND

Diamond "Shah" (approx. 89 carats).


mineral, the only gem A that has one element. The name probably comes from the Greek. "adamas" (invincible, irresistible) or from the Arabic "al-mas" (Persian "elma") - very hard. Diamond is crystalline carbon. Carbon exists in several solid allotropic modifications, i.e. in different forms with different physical properties. Diamond is one of the allotropic modifications of carbon and the hardest known substance (hardness 10 on the Mohs scale). Another allotropic modification of carbon - graphite - is one of the softest substances. The exceptionally high hardness of diamond is of great practical importance. It is widely used in industry as an abrasive, as well as in cutting tools and drill bits.

Diamond crystallizes in a cubic (isometric) syngony and usually occurs in the form of octahedrons or crystals of a similar shape. When a diamond is chipped, fragments of the mineral are split off from the parent mass. This is made possible by perfect cleavage. The color is varied. Usually diamonds are colorless or yellowish, but blue, green, bright yellow, pink-purple, smoky-cherry, red stones are also known; There are also black diamonds. Diamond is transparent, sometimes translucent, sometimes opaque. The diamond does not give features; its powder is white or colorless. The density of diamond is 3.5. The refractive index is 2.42, the highest among ordinary gemstones. Since the critical angle of total internal reflection for this mineral is only 24.5°, the facets of a cut diamond reflect more light than other stones with a similar cut, but with a lower refractive index. Diamond has a very strong optical dispersion (0.044), as a result of which the reflected light is decomposed into spectral colors. These optical properties, combined with the extraordinary purity and transparency of the mineral, give the diamond a bright brilliance, sparkle and play. Diamonds usually luminesce in x-rays and ultraviolet rays. In some varieties of diamond, the luminescence is very pronounced. Diamonds are transparent to x-rays. This facilitates the identification of a diamond, since some glasses and colorless minerals, such as zircon, sometimes outwardly similar to it, are opaque to X-rays of the same wavelength and intensity. The luminescence of diamond is due to the presence of nitrogen impurities in it. Approximately 2% of diamonds do not contain nitrogen and do not fluoresce; usually these are small stones. The exception is "Cullinan" - the largest jewelry diamond in the world. The main producers of diamonds are Australia, Russia, South Africa and the Democratic Republic of the Congo, which together account for more than 3/5 of the world's diamond production. Other major producers are Botswana, Angola and Namibia. India, which was the only source of diamonds before the 18th century, produces comparatively few of them at the present time. Gem-quality diamonds are found in South Africa and in the Republic of Sakha (Yakutia, Russia) in kimberlites - dark granular ultrabasic volcanic rocks composed mainly of olivine and serpentine. Kimberlites occur in the form of tubular bodies ("explosion pipes") and usually have a brecciated structure. From several tons of mined kimberlite, fractions of a carat of high-quality diamond are extracted. Diamonds are also mined from alluvial (river) and coastal-marine pebble placers, where they were taken out as a result of the destruction of diamond-bearing kimberlite volcanic breccia. Under such conditions, gemstones usually acquire a rough surface. They are often the best cutting stones, as they have withstood the ravages of impacts on the stones when carried by streams or sea waves in the surf zone, and therefore should present a strong solid mass, relatively free from internal stresses. There are cases when diamonds mined from kimberlite pipes exploded, which indicates a colossal stress inside the stone. This phenomenon provides the key to understanding that the crystallization of diamonds must have taken place under conditions of enormous pressures. Most cut diamonds, when examined in polarized light, reveal the presence of internal stresses. It is believed that diamonds were formed at great depths in the Earth's mantle, and then at least 3 billion years ago were brought to the surface by powerful explosions. Diamonds have also been found in meteorites.


The brilliance and beauty of a diamond is fully revealed only after cutting. For a long time it was believed that L. van Berkem from Bruges at the end of the 15th century. developed a method of precise symmetrical cutting (still used today), consisting in grinding a stone on an iron wheel, on which a mixture of diamond powder and oil is applied. Now the existence of this master is being questioned. The above method is believed to have been developed in India. Previously, it was also believed that the brilliant cut (the main type of cutting of rounded diamonds at the present time) was invented by the Italian cutter Vincenzo Peruzzi at the end of the 17th century, but this opinion turned out to be erroneous. Brilliant cutting was developed gradually throughout the 17th century. Previously, other types of symmetrical and carefully designed cuts had been created. For example, the rose cut, when the stones are in the form of a drop of resin (i.e., a flat base and a dome cut with triangular facets), probably appeared at the beginning of the 16th century. However, the brilliant cut, which is close to the modern one, took shape only at the beginning of the 20th century, when the proportions and angles necessary to give the stone maximum sparkle were established. Jewelers call this cut "old miner's". Currently, the diamond cut is even more perfect. Any faceted stone, including a diamond, consists of two parts: the upper one - the crown and the lower one - the pavilion. Between them is a narrow girdle, or girdle (the widest part of the diamond). An ordinary round diamond has 58 facets, or facets (artificial facets). These include: 1 octagonal table (platform) crowning the crown, 8 star facets, 4 main crown facets, 4 corner crown facets, 16 upper facets of the girdle (adjacent to it from above), 16 lower facets of the girdle (directly below it), 4 corner facets of the pavilion, 4 main facets of the pavilion and 1 facet at the tip of the pavilion (culet; now applied very rarely). Interest in diamonds is explained by the romantic halo that surrounds many famous gems. Thus, the diamond "Koh-i-nor" ("Mountain of Light") was found in the mines of Golconda (India). According to legend, in 1304 Sultan Ala-ad-Din Khilji took it away from the Rajah of the Principality of Malwa, in whose family the stone had been for many generations. When it came into the possession of Britain in 1849, it was an incorrectly cut "oval rose" stone weighing 186 carats (1 carat = 0.2 g). By order of Queen Victoria, it was recut, after which the mass of the stone decreased to 108.93 ct. The most remarkable diamond - "Cullinan" - was discovered in 1905 in the Transvaal (South Africa). The mass of this magnificent gemstone in its raw (uncut) form was 3106 carats (621 g). It was presented as a gift to King Edward VII of Great Britain. It was used to make a diamond ("Star of Africa") weighing 530.2 carats, another diamond weighing 317.4 carats and seven stones weighing from 94.45 to 4.39 carats each. In addition, another 96 small diamonds with a total weight of 7.55 carats were cut from its fragments. During the cutting process, 66% of the original mass of the stone was lost. The "Pitt" or "Regent" diamond had several owners, famous and unknown, in the East Indies, Britain and France. Its mass now is 140.5 carats (originally - ca. 410 carats). Other historical diamonds are Orlov, Sancy, Shah, Nassak, Dresden Green and Hope. The second largest known gem diamond after the Cullinan is Excelsior (995.2 carats), discovered in South Africa in 1893. The third largest diamond is the Star of Sierra Leone (969.8 carats) found in 1972 in Sierra Leone The first attempts to obtain artificial diamonds were made as early as the end of the 19th century, but all of them were unsuccessful.Only in December 1954, the scientists of the General Electric Company F. Bundy, T. Hall, G. M. Strong and R. Kh. Wentorf synthesized diamonds on apparatus designed by P. W. Bridgman of Harvard University Under a pressure of 126,600 kg/cm2 and at a temperature of 2430° With this scientist, small technical diamonds were obtained from graphite. In the USSR, artificial diamonds were made in 1960 at the Institute physics of high pressures of the Academy of Sciences of the USSR, led by L.F. Vereshchagin, and their industrial production was established in Kiev in 1961. At present, technical diamonds are produced on an industrial scale.In 1970, Strong and Wentorf managed to obtain gem-quality artificial diamonds. Such diamonds are made by dissolving synthetic diamond powder in a bath of molten metal. The carbon atoms from the dissolved powder migrate to one end of the bath, where tiny diamond seed crystals are placed. Carbon atoms settle and crystallize on these crystals, which grow into diamonds of one carat or more. This process requires extremely high pressures and temperatures. Today, artificial gem diamonds are more expensive than natural ones, and their production is unprofitable. The massive interest in diamonds is explained by their value as precious stones, but they are even more important as a material for reinforcing metal-cutting and other tools widely used in industry (cutters, drills, dies, dies, circular saws, drill bits, etc. . ), and also as abrasives (diamond powders). Jewelry diamonds, i.e. their transparent colorless (or slightly yellowish) and beautifully colored crystals make up only a small fraction of all mined stones. The vast majority of natural diamonds, as well as all artificial diamonds, are industrial diamonds called "board". The black variety of technical diamonds - carbonado - consists of aggregates of small diamond grains interconnected into a dense or porous mass. Tools reinforced with technical, natural or artificial diamonds are used for metal processing. They are used for sawing, cutting, turning, boring, drilling, turning, stamping, drawing, etc. steel and other metals, carbides, aluminum oxide (artificial corundum), quartz, glass, ceramics and other hard materials, as well as for drilling wells in hard rocks. Diamond saws are used in the extraction and processing of building stone and for cutting ornamental stones. Diamond powder is used for roughing, grinding and polishing steels and alloys, as well as for grinding and cutting diamond jewelry and other hard precious stones. Drilling a hole in a diamond to enable it to be used as a die requires well-sorted (narrowly graded) diamond powder, fine steel needles, and lubricating oils. The hole can be punched in other ways - using a laser beam or an electric spark discharge. Such methods make it possible to make very small holes with a diameter of only 10 microns in diamond drawing dies.
see also
ABRASIVES ;
GEMS ;
METAL-CUTTING MACHINES.

Collier Encyclopedia. - Open society. 2000 .

Synonyms:

See what "DIAMOND" is in other dictionaries:

    The first is between gems; the Greeks called him invincible (for a long time, back in the Middle Ages, the belief was that the diamond was dissolved in fresh goat blood) adamaV, from where its name comes from: Diamant. Diamond crystallizes in the correct ... ... Encyclopedia of Brockhaus and Efron

    Female the first in brilliance, hardness and value of expensive (honest) stones; adamant, diamond. Diamond, pure carbon in galleys (crystals), burns without residue, forming carbonic acid. Diamond is a common name: a diamond, more valuable in size and ... ... Dahl's Explanatory Dictionary

    Diamond- a typical covalent crystal with a number of unique properties: the highest hardness among known materials, compressive strength, crack resistance. Pure diamonds are one of the best insulators and are almost transparent... ... Metallurgical Dictionary

    Almas (borrowed, male) "diamond" (Greek) Gypsy names. Dictionary of meanings.. DIAMOND Diamond (precious stone, diamond). Tatar, Turkic, Muslim male names. Glossary of terms ... Dictionary of personal names

    - (Turk. elmas). The hardest and most brilliant of gems; diamonds polished in a known way are called brilliants. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. DIAMOND arab. el mas… … Dictionary of foreign words of the Russian language

DIAMOND (Turk. almas, from Greek adamas - invincible, invincible * a. diamond; n. Diamant; f. diamant; and. diamante) - crystalline cubic modification of native.

Structure of a diamond. The unit cell of the spatial crystal lattice of diamond is a face-centered cube with 4 additional atoms located inside the cube (Fig.).

Unit cell edge size a 0 = 0.357 nm (at t = 25°C and P = 1 atm). The shortest distance between two neighboring atoms C = 0.154 nm. The carbon atoms in the structure of diamond form strong covalent bonds directed at an angle of 109°28" relative to each other, making diamond the hardest substance known in nature. In the band structure of diamond, the band gap for non-vertical transitions is 5.5 eV, for vertical - 7.3 eV, valence band width 20 eV Electron mobility mn = 0.18 m 2 /V.s, holes mr = 0.15 m 2 /V.s.

Morphology of the diamond. Diamond crystals have the shape of an octahedron, rhombic dodecahedron, cube and tetrahedron with smooth and lamellar-step faces or rounded surfaces on which various accessories are developed. Flattened, elongated and complexly distorted crystals of simple and combined forms, twins of intergrowth and intergrowth according to the spinel law, parallel and arbitrarily oriented intergrowths are characteristic. Varieties of diamond are polycrystalline formations: bead - intergrowths of numerous small faceted crystals and grains of irregular shape, gray and black; ballas - spherulites of a radially radiant structure; carbonado - cryptocrystalline, dense, with an enamel-like surface or slag-like porous formations, consisting mainly of submicroscopic (about 20 microns) diamond grains, closely fused with each other. The size of natural diamonds ranges from microscopic grains to very large crystals weighing hundreds and thousands of carats (1 carat = 0.2 g). The mass of mined diamonds is usually 0.1-1.0 carats; large crystals (over 100 carats) are rare. The table shows the world's largest diamonds extracted from the bowels.

Chemical composition. The diamond contains impurities Si, Al, Mg, Ca, Na, Ba, Mn, Fe, Cr, Ti, B number. With the help of a-particles of radioisotope H, N, O, Ar and other elements. is the main impurity that has a great influence on the physical properties of diamond. Diamond crystals that are opaque to ultraviolet radiation are called type I diamonds; all others are type II. The nitrogen content in the vast majority of type I diamond crystals is about 0.25%. Less common are nitrogen-free diamonds of type II, in which the admixture of nitrogen does not exceed 0.001%. Nitrogen enters the diamond structure isomorphically and forms, alone or in combination with structural defects (vacancies, dislocations), centers responsible for color, luminescence, absorption in the ultraviolet, optical, infrared and microwave regions, the nature of X-ray scattering, etc.

Physical properties . Diamonds can be colorless or with a subtle color tint, as well as varying degrees of clearly colored yellow, brown, mauve, green, blue, blue, milky white and gray (to black) colors. When irradiated with charged particles, the diamond acquires a green or blue color. The reverse process - the transformation of a colored diamond into a colorless one - has not yet been carried out. Diamond is characterized by strong brilliance, a high refractive index (n = 2.417) and a strongly pronounced dispersion effect (0.063), which causes a multi-colored play of light in. As a rule, anomalous birefringence appears in diamond crystals due to stresses arising from structural defects and inclusions. Diamond crystals are transparent, translucent or opaque depending on saturation with microscopic inclusions of graphite, other minerals and gas-liquid vacuoles. When illuminated with ultraviolet rays, a significant part of transparent and translucent diamond crystals luminesces in blue, light blue and less often yellow, yellow-green, orange, pink and red. Diamond crystals (with rare exceptions) luminesce when exposed to X-rays. The glow of a diamond is excited by cathode rays and when bombarded by fast particles. After excitation is removed, an afterglow of varying duration (phosphorescence) is often observed. Diamond also exhibits electro-, tribe-, and thermoluminescence.

Diamond, as the hardest substance in nature, is used in a variety of tools for sawing, drilling and processing all other materials. Relative on the Mocca 10 scale, the maximum absolute microhardness measured by the indenter on the face (111), 0.1 TPa. The hardness of diamond on different crystallographic faces is not the same; the hardest is the octahedral face (111). Diamond is very brittle, has a very perfect cleavage along the (111) face. Young's modulus 0.9 TPa. The density of transparent diamond crystals is 3515 kg / m 3, translucent and opaque - 3500 kg / m 3, for some Australian diamonds - 3560 kg / m 3; at the side and carbonado due to their porosity can be reduced to 3000 kg/m 3 . The clean surface of diamond crystals is high (contact angle 104-105°). In natural diamonds, especially in diamonds from alluvial deposits, the thinnest films are formed on the surface, which increase its wettability.

Diamond is a dielectric. The specific resistance r for all type I nitrogen diamond crystals is 10 12 -10 14 Ohm.m. Among nitrogen-free diamonds of type II, sometimes there are crystals in which r is below 10 6 Ohm.m, sometimes up to 10-10 -2. Such diamonds have r-type conductivity and photoconductivity, and under the same conditions, the photocurrent in type II diamond is an order of magnitude greater than the photocurrent excited in type I diamond. Diamond is diamagnetic: the magnetic susceptibility per unit mass is 1.57.10 -6 SI units at 18°C. Diamond is resistant to all acids even at high temperatures. In melts of alkalis KOH, NaOH and other substances in the presence of O, OH, CO, CO 2 , H 2 O, oxidative dissolution of diamond occurs. Ions of some elements (Ni, Co, Cr, Mg, Ca, etc.) have catalytic activity and accelerate this process. Diamond has a high thermal conductivity (especially nitrogen-free type II diamonds). At room temperature, their thermal conductivity is 5 times higher than Cu, and the coefficient decreases with increasing temperature in the range of 100-400 K from 6 to 0.8 kJ / m.K. The polymorphic transition of diamond into at atmospheric pressure occurs at a temperature of 1885±5°C throughout the entire volume of the crystal. The formation of graphite films on the surface of faces (III) of diamond crystals under the influence can occur starting from 650°C. In air, diamond burns at a temperature of 850°C.

Prevalence and origin. Diamonds have been found in meteorites, impact rocks associated with meteorite craters (astroblems), in small deep mantle rocks of pre-githic and eclogitic compositions located in them, as well as in secondary sources - placers of different age and genesis ( , etc. ). There is no consensus on the origin of diamonds. Some scientists believe that diamonds crystallize in the kimberlite pipes themselves during their formation or in intermediate chambers that occur at shallow (3-4 km) depths (subvolcanic chambers). Others believe that diamonds are formed at great depths in the parent kimberlite melt and continue to crystallize as it rises into upper part. The idea that diamonds are genetically related to diverse rocks and are removed from them along with other xenogenic material found in kimberlites is most justifiably developed. There are other ideas about the genesis of diamond (for example, crystallization at low pressures using carbon from abyssal origin and carbonates of host rocks).


Diamond deposits. Diamond-bearing kimberlite rocks and alluvial deposits formed due to their erosion are of industrial importance. Kimberlites are found mainly on ancient and; they are characterized mainly by tubular bodies, as well as huskies and. The dimensions of kimberlite pipes are from one to several thousand meters in cross section (for example, the Mwadui pipe in Tanzania with parameters of 1525x1068 m). More than 1500 kimberlite bodies are known on all platforms, but only a few diamonds have industrial content. Diamonds are distributed extremely unevenly in kimberlites. Pipes with a diamond content of 0.4 carats/m 3 and above are considered industrial. In exceptional cases, when pipes contain an increased percentage of high-quality diamonds, exploitation with a lower content, for example, 0.08-0.10 carats/m 3 (Jägersfontein in South Africa), can be profitable. Kimberlites are dominated by crystals 0.5-4.0 mm in size (0.0025-1.0 carats). Their weight fraction is usually 60-80% of the total mass of recovered diamonds. Reserves at individual deposits amount to tens of millions. The largest primary diamond deposits have been explored in Tanzania, Lesotho, Sierra Leone and others.

Enrichment. In alluvial deposits, the rock is first washed in order to remove the binding clay mass and separate large clastic material; the isolated loose material is divided into four classes: -16+8, -8+4, -4+2, -2+0.5 mm. produced by gravitational methods (wet and air, enrichment in heavy suspensions, in concentration bowls). To extract small diamonds and diamond chips, film and foam are used with preliminary cleaning of the surface. Reagents: amines, aeroflots, fatty acids, kerosene, cresyl acid. To extract diamonds, the fat process (for grains with a size of 2-0.2 mm) is most widely used, based on the selective ability of diamonds to stick to fatty surfaces. Vaseline, petroleum, autol and its mixture with paraffin, oleic acid, nigrol, etc. are used as a fat coating. poor conductor of electricity). An X-ray luminescent method is used to extract relatively large diamonds, based on the ability of diamond crystals to luminesce (X-ray luminescent machines).

Application. Diamonds are divided into jewelry and technical. The former are highly transparent. The most valuable diamonds are colorless ("pure water") or with a good color. Technical diamonds include all other mined diamonds, regardless of their quality and size. In the CCCP, diamonds are sorted according to specifications, which are supplemented as the areas of application of diamonds expand. Depending on the types and purpose, rough diamonds are classified by quality into categories; in each category, groups and subgroups are distinguished, which determine the size, shape, specific conditions for the appointment of diamond crystals. About 25% of the diamonds mined in the world are used in the jewelry industry to make polished diamonds.

With exceptionally high hardness, diamonds are indispensable for the manufacture of various tools and devices (and, indenters for measuring the hardness of materials, drawing dies, needles for profilometers, profilographs, pantographs, drills, cutters, applied stones for marine chronometers, glass cutters, etc.). Diamonds are widely used for the manufacture of abrasive powders and pastes, for refilling diamond saws. Some metals, semiconductor materials, ceramics, building reinforced concrete materials, crystal, etc. are processed with diamond tools. Due to the combination of a number of unique properties, diamonds can be used to create electronic devices designed to operate in strong electric fields, at high temperatures, under conditions of high radiation levels , in aggressive chemical environments. On the basis of diamonds, nuclear radiation detectors, heat sinks in electronic devices, thermistors and transistors have been created. The transparency of diamonds for infrared radiation and the weak absorption of X-rays make it possible to use them in infrared receivers, in chambers for studying phase transitions at high temperatures and pressures.

Synthetic diamonds. In the mid 50s. began the development of industrial synthesis of technical diamonds. Synthesized mainly small single crystals and larger polycrystalline formations such as ballas and carbonado. The main methods of synthesis are: static - in the metal-graphite system at high pressures and temperatures; dynamic - polymorphic transition of graphite in diamonds under the influence of a shock wave; epitaxial - the growth of diamond films on diamond seeds from gaseous hydrocarbons at low pressures and temperatures of about 1000 ° C. Synthetic diamonds are used in the same way as natural industrial ones. The total production of synthetic diamonds significantly exceeds the production of natural ones.

Diamond (from Arabic ألماس, ’almās, Tur. elmas, which goes through Arabic from other Greek ἀδάμας - “indestructible”) is a mineral from the class of native elements, one of the allotropic modifications of carbon. Chemical formula: S.

Diamond has the same chemical composition like graphite. But in appearance it differs sharply from it. This difference is explained by the different arrangement of carbon atoms in the crystal lattice: in diamond they are placed in a tetrahedral structure and have a strong bond in all directions. Specific gravity 3.48-3.55 g/cm3. Diamond is a stone with unusual brilliance, play of colors, inner fire. The brilliance of a diamond is strong - diamond. Diamond is very hard - "the king of all minerals."

On the Mohs scale, hardness is 10. In terms of hardness, it is not inferior to any of known minerals. Diamond is the "champion of hardness": it is 1000 times harder than quartz, 150 times harder than corundum. Maybe that's why the ancient Greeks considered the diamond a talisman of power. Diamond is resistant to acids, heat. It is the only mineral that scratches corundum. On this basis, it differs from minerals similar to it - rock crystal, topaz, etc. Diamond is very hard, but at the same time fragile. It easily splits along the cleavage planes. Cleavage is perfect but to the faces of the octahedron. This property of a diamond is used by jewelers when processing it. A new mineral with great hardness has been found, the "brother" of diamond - yakutite.

No gem has as many shades as a diamond: colorless, white, blue, green, yellowish, pink, reddish, brownish, smoky gray tones; often transparent.

Diamond is found mostly in the form of individual crystals - octahedrons with curved edges, in external shape approaching a ball. Crystal sizes are usually small. Crystallizes in the cubic syngony.

Features. Characteristic features for a diamond are a strong diamond splash and high hardness - it leaves a scratch on corundum. If metallic aluminum is used to draw on the wetted surface of a diamond, the aluminum leaves no traces.

Varieties and photos of diamond

  1. Diamond- an artificially processed diamond with 57 facets. A diamond scatters sunlight like raindrops forming a rainbow, a diamond is the most radiant gemstone.
  2. Board- Irregular fine-grained splices.
  3. Ballas- spherical diamond, radial-radiant structure.
  4. Carbonado- black, gray, dense or coarse-grained diamond.
  5. Yakutit- dark diamond with numerous inclusions and maximum hardness.

Colorless diamond, Catoca, Angola Bort Spherical ballas Black carbonado

Origin of diamond

Diamond deposits are genetically related to ultrabasic (dunites, peridotites) and basic (diabases) igneous rocks and to serpentinites resulting from chemical alteration of ultrabasic and basic rocks. Diamond is formed under conditions of high pressure and high temperature, so its deposits are confined to volcanic explosion funnels. Diamond is formed at a pressure of more than 5 MPa and a temperature of about 2000 ° C.

The formation of diamonds is closely related to tectonic processes. At the same time, a fiery-liquid mass, the so-called ultrabasic magma, rose from great depths along those that arose in the earth's crust. It is sometimes called kimberlite. As the kimberlite magma ascended, it cooled and this led to the separation of dissolved volatile compounds (gases, water vapor). The released water vapor and gases caused strong explosions, as a result of which vertical well-shaped cylindrical holes appeared in the earth's crust - kimberlite pipes. These tubes were filled with crushed rocks formed during the explosion. Then, along a funnel filled with clastic material, kimberlite magma rose, which occupied the voids between the debris and cemented them.

The diamonds are thought to have erupted mostly in solid form when the kimberlite magma was still at depth, and then they were carried by the magma flow into the kimberlite pipes. Diamonds contain only those pipes whose roots reach the diamondiferous layer. Diamonds are formed at depths of about 200 km.

Findings of diamonds are known not only on platforms (on the plains), but also in mountainous areas: in the Urals, in the Appalachians, the Cascade Mountains, the Sierra Nevada, on about. Kalimantan and other areas.

Diamonds are found in meteorites. Diamond is also formed during explosions that accompany the fall of huge meteorites (Meteoritic Crater "Devil's Canyon", Arizona, USA).

It occurs among basic and ultrabasic igneous rocks, among serpentinites (serpentines); also in ancient (conglomerates, sandstones) and young placers.

satellites. In primary deposits: serpentine, olivine, augite, graphite, magnetite, chromite, ilmenite, talc. In placers: quartz, platinum, gold, magnetite, ilmenite, hematite], topaz, cassiterite, corundum. A constant companion of diamond is pyrope, a cherry-colored mineral. Pyrope is more common than diamond, and serves as a good "landmark" when looking for diamond deposits.

Application of diamond

Diamonds are divided into jewelry and technical. The former include transparent, colorless or slightly colored varieties of more or less large sizes; to technical ones - dark marginal differences and small-sized diamonds. In the deposits, as a rule, technical diamonds predominate, gem grades are less common.

Diamond is called the hero of technology. Up to 80% of diamonds mined worldwide are used in industry. Diamonds are used in the electrical, radio-electronic and instrument-making industries. Diamonds are used as nuclear radiation detectors, in fast particle counters, and in medical counters. They are used in space research, in the study of the deep structure of the Earth. The use of diamond for cutting glass is well known. A 1-carat diamond (a carat equals 0.2 g) can cut window glass 2,500 km long.

A diamond, comparable to the transparency of spring water, shimmers with all the colors of the rainbow and is also used as jewelry (diamond). It is valued more than a hammer. For the cost of a diamond the size of an apricot, you can build an entire factory. The high price of a diamond is explained not so much by its high hardness, strong brilliance, beautiful “play” of colors, but by its rarity. Large deposits are rare. Even in rich deposits, 3-6 small diamond grains are found in one cubic meter of rock.

On average, only about 5 kg of diamonds are extracted from 100,000 tons of rock. The ratio is 20 million to 1.

The history of the diamond has more than five thousand years. Eminent diamonds and other precious stones are witnesses of power, immense splendor of royal outfits, people's grief, suffering. Diamonds adorned crowns and other attributes of power of pharaohs, shahs and kings.

Many of the big diamonds have bloody histories full of secrets, tragedies, nightmarish crimes, applied by fleeting greedy joy in the world of gain.

Diamond deposits

Africa is the Diamond Continent. The main diamond-producing countries on African soil are: the Republic of Zaire, which ranks first in the world in the extraction of industrial diamonds, Tanzania, Ghana, South Africa (the country of diamonds is Namibia, which ranks first in the world in the extraction of gem diamonds, illegally occupied by South Africa), Angola, Guinea and other. One of the richest in Africa and in the world are the diamond deposits of the Central African Empire. Then come the countries of South America: Brazil, Venezuela, Guyana and Asian countries: India, Indonesia.

In South Africa in 1905, two giant diamonds were found. The largest of them is "Cullinan" (named after the owner of the mine) weighing 3106 carats (the size of a fist), the second - "Excelsior" - 971.5 carats. Both diamonds were sawn and cut into smaller diamonds and sold. The Cullinan yielded 105 diamonds after sawing. Two of them - the largest - are inserted into the royal scepter and the imperial crown of England. In Sierra Leone, in the Enge-ma region (West Africa), a large diamond was found the size of a small chicken egg. It weighs 968.9 carats (almost 200 g). Its length is 40 mm. They called it the "Star of Sierra Leone". In the international list of rare diamonds, it ranks third. Diamond "Star of Sierra Leone" cut into 11 individual stones of a high price. The quality of Sierra Leonean diamonds is one of the best. The largest Indian diamond "Great Mogul" - 794 carats. Large diamonds "Orlov" (194.8 carats) and "Koh-i-nur" (109 carats) were found in India.

The largest flat diamond has an area of ​​7.5 cm2. It is mounted in a gold bracelet; stored in the diamond fund of Russia. One of the largest light blue diamonds of 42.27 carats was found in the Republic of South Africa (Orange Province).

The very first diamond in Russia was found by 14-year-old serf Pavel Popov in the Urals in the 19th century. After such a precious find, geologists explored the Urals and Siberia for almost 100 years, until the geologist Larisa Popugaeva in June 1954 found the first Zarnitsa kimberlite pipe in cold Yakutia. The name of Larisa Popugaeva bears one diamond weighing 29.4 carats.

The Yakut diamond is clean and transparent, as if the fortress of the Yakut frost has absorbed the beauty of the northern lights. About ten kimberlite pipes have been discovered on the territory of Yakutia: Aikhal, Zarnitsa, International, Mir, the world's largest Udachnaya, Yubileinaya. One of the large Soviet diamonds "Maria" weighs 105.98 carats. A diamond weighing 342.5 carats was found in the Mir pipe on December 23, 1980 and named after the 17th Congress of the CPSU, which took place 3 months after the discovery. IN modern Russia Two finds stand out, made in 2003 in the Udachnaya pipe: lemon-colored and tobacco-colored diamonds, weighing 301.55 and 232.7 carats, respectively.

Kimberlite pipes and associated diamond deposits are found in Russia not only in Yakutia. The discovery of diamond deposits here was the discovery of the Pomorskaya kimberlite pipe in 1980, which, in addition to another 5 pipes (Pionerskaya, Karpinsky-1 ″, Karpinsky-2, Arkhangelskaya and Lomonosov) is part of the largest placer diamond deposit in the European part of Russia - named after M.V. Lomonosov. Here, the largest in the history of the development of the deposit is a diamond weighing 50.1 carats. In the Arkhangelsk region, in addition to the Lomonosov deposit, the V.P. Mushroom (Verkhotinskoe).

One of the promising diamond-bearing regions in Russia is the Irkutsk region, where the search for gems was stopped in 1980 due to insufficient funding and negative results obtained in the southern part of the region.

In 2015, a number of scientists conducted an analysis that suggests that the Orenburg region has prospects for the presence of diamond-bearing regions.

Diamond is a simple non-metal substance that consists almost entirely of carbon. This mineral is known for its wide use in jewelry, as well as for its unusual physical properties, among which the highest strength stands out. At the same time, the chemical formula of diamond is the same as that of ordinary graphite - C, and its uniqueness and value is due solely to the structure of the crystal lattice.

Formula and structure of the mineral

Carbon, also known as carbon, is an element that has the sixth serial number in the periodic table and is written as C. It is from it that diamond is entirely composed - the amount of impurities, if any, is so small that they are not taken into account in the formula. Apart from the diamond carbon takes the following allotropic, that is, consisting of one substance, forms:

  • charcoal;
  • soot;
  • graphite;
  • graphene;
  • carbine;
  • coke;
  • hexagonal diamond, or lonsdaleite;
  • fullerene;
  • polycumulene;
  • CNTs or carbon nanotubes.

It is hard for some to believe that a transparent and durable diamond has the same composition as ordinary soot, coal or graphite, but it is true. The fact is that, unlike other substances consisting of carbon, diamond atoms form a cubic ordered structure, which explains its unusual qualities and appearance.

The crystal lattice of the mineral has a cubic shape. Each atom in its structure is located in the center of a tetrahedron, the vertices of which are 4 other atoms, while a reliable sigma bond is formed between them. The distance between all atoms is the same and is approximately 0.15 nm. In addition, the mineral lattice is characterized by cubic symmetry. All these qualities and features of the structural formula of diamond determine its enormous strength in comparison with “relatives” substances.

Substance characteristics

Ideally, a gemstone should be pure carbon, but this is rare in nature. Impurities in a mineral can both negatively affect its quality, reducing the price, and give it beautiful and unusual shades. Even the color can sometimes be affected by radioactive radiation. Usually natural diamonds - yellow, but there are also blue, blue, green, pink and even red specimens. Despite the variety of shades, a pure mineral should always be transparent.

In nature, diamonds have a variety of shapes. Most often there is a crystal with eight faces in the form of a regular triangle. In second place is a rhombic dodecahedron with twelve faces. There are also cubic and round stones, but they are very rare. When cutting a mineral, they try to minimize the loss of substance in order to maximize the profit from the production of diamonds.

Mining and production

None of these methods can yet create stones that are close to natural in quality, because they are rarely used in jewelry. In addition, all types of production are far from mass production, because the efforts of scientists in this matter are still ongoing.

Application of diamond

A cut diamond, also known as a brilliant, is a very popular gemstone, which is also one of the most expensive. Although for sale as jewelry only a small part of the mineral comes in, it is she who makes up the bulk of the income from its extraction. To a large extent, the high cost of the stone is due to the monopolization of the production of diamonds - more than 50% of their turnover belongs to one company.

In addition to jewelry, there are many other industries in which the mineral has found its application. Its highest strength, due to the structural formula of diamond, is mainly valued. In chemistry, it is used to protect against acids and some very caustic substances. In industry, a diamond film is applied to cutters, drills, knives, parts of mining installations and other similar tools. Diamond grit is used as an abrasive for grinding grinding surfaces.

It is also used in the creation of medical instruments., since the sharpness and strength of diamond products can provide the most accurate cuts during operations. It is also used to make parts for modern quantum computers and watches, in the nuclear industry, as well as in many other industries.