What is a diamond in simple words?
Diamond is the hardest mineral. Its hardness is 10 on the Mohs scale and this is the maximum. The absolute hardness of diamond is 1000 times higher than the hardness of quartz and 150 times the hardness of corundum.
The density of the mineral is 3,5-3,52, this is certainly not a record, but it is also a lot. For diamonds, the characteristic crystal shapes are octahedrons and dodecahedrons (tetrahedrons); fusion twins occur; crystals are sometimes characterized by etching patterns, shading, curvature of edges, and irregular, distorted crystals are observed.
Crystal structure
Face-centered cube lattice; each atom is surrounded by four others arranged in a tetrahedron. Cleavage. Octahedron perfect (111), brittle. P. tr. In powder, it burns on a platinum wire to form carbon dioxide (CO3); when access to air is stopped and at a temperature of 1500°C, it turns into graphite. Behavior in acids. Insoluble.
Origin
At the moment, there is no exact, scientifically proven theory of the origin of diamonds. There are a wide variety of hypotheses, but the majority of scientists are inclined towards the magmatic and mantle theories. At great depths (120-200 km), carbon atoms under high pressure (45-60 thousand atmospheres) and at high temperatures (900-1300°C) form a cubic crystal lattice – diamond. Rocks containing diamonds are brought to the surface using “explosion tubes.” There are also diamonds of meteorite (extraterrestrial) origin. When large meteorites fall during impact metamorphism, diamonds can also be formed, for example, in the Popigai astrobleme in northern Siberia.
Related Minerals
- in kimberlites: forsterite, phlogopite, pyrope, diopside, ilmenite;
- in placers: ilmenite, garnets, rutile, brookite, anatase, hematite, magnetite, tourmalines, gold, zircon, topaz
Diamonds are also obtained artificially.
A bit of history
Five thousand years ago, people became aware of the most beautiful stone, the diamond, which was mesmerizing in its beauty, captivating the souls and minds of many. Thousands of novels and stories, hundreds of films and millions of human destinies are connected with this charming stone. By its nature, it fully justifies its proud name, given to it by the ancient Greeks. Diamond in translation means indomitable. HE stubbornly defies the hands of a grinder and the insightful mind of a scientist, chemical reagents and the mighty power of time.
The ancient Hindus had a belief regarding the composition of diamonds, or rather the proportions of the basic elements of the universe contained in them, i.e. – water, earth, air, sky and energy. If the base of the stone is earth, then the diamond is dense; water – smooth, transparent, heavy; air – the diamond is pointed and light; if it has the advantage of heaven – the stone is clean, exceptionally shiny and has sharp edges; Diamonds, which have energy as their main essence, most often have a blood-red light.
Also, each type was given its own magical properties: a watery diamond gives fame, wealth and satisfaction, an earthy diamond contributes to the conquest of absolute earthly power, aerial diamonds gave cordiality and grace, heavenly health, and those in which energy was the basis – courage, power, hope. Struck by its splendor and durability, they dedicated it to their deities and placed it at the head of precious stones.
Properties of the Mineral
| Color | colorless, yellowish, brown, sometimes green, blue, reddish, black |
| Line color | Does not have: scratches the test plate |
| Precious stone | according to the legislation of the Russian Federation |
| Origin of the name | from the ancient Greek ἀδάμας – indestructible |
| Opening year | known since ancient times |
| IMA status | valid, first described before 1959 (before IMA) |
| Chemical formula | C |
| Brilliance | fatty diamond |
| Transparency | transparent translucent opaque |
| Cleavage | perfect |
| Kink | conchoidal uneven |
| Hardness | 10 |
| Thermal properties | Diamond has the highest thermal conductivity. P. tr. In powder, it burns on a platinum wire to form carbon dioxide (CO3); when access to air is stopped and at a temperature of 1500°C, it turns into graphite. |
| Luminescence | In caode and x-rays, all varieties luminesce with blue-white light; in UV rays, some, mainly in blue tones, but other colors are also possible |
| Strunz (8th edition) | 1/B.02-40 |
| Hey’s CIM Ref. | 1.24 |
| Dana (7th edition) | 1.3.5.1 |
| Dana (8th edition) | 1.3.6.1 |
| Molecular weight | 12.01 |
| Cell Options | a = 3.5595Å |
| Number of formula units (Z) | 8 |
| Unit cell volume | V 45.10 ų |
| Twinning | Twins of germination according to the spinel law are common |
| Point group | m3m (4/m 3 2/m) -hexoctahedral |
| Space group | Fm3m (F4/m 3 2/m) |
| Density (calculated) | 3.515 |
| Density (measured) | 3.5 – 3.53 |
| Pleochroism | does not pleochroate |
| Optical axis dispersion | strong |
| Refractive indices | nα = 2.418 |
| Maximum birefringence | δ = 2.418 – isotropic, does not have birefringence |
| Type | isotropic |
| Optical relief | moderate |
| Selection form | octahedrons, dodecahedrons (tetrahedrons); fusion twins occur; spherulites with a radial structure, irregular, distorted crystals |
| Classes on taxonomy of the USSR | Nonmetals |
| IMA classes | Native elements |
| Syngonia | cubic |
| fragility | Yes |
| wikipedia | http://ru.wikipedia.org/wiki/%C0%EB%EC%E0%E7 |
| Literature | Diamond. Directory, K., 1981 Afanasyev V.P., Efimova E.S., Zinchuk N.N., Koptil V.I. Atlas of the morphology of Russian diamonds. Novosibirsk: Publishing House of the Scientific Research Center SB RAS OIGGM, 2000. Vaganov V.I. Diamond deposits in Russia and the world (Fundamentals of forecasting). M.: Geoinformmark, 2000. 371 p. Garanin V.K. Introduction to the mineralogy of diamond deposits. M.: MSU, 1989, 208 p. Garanin V.K., Kudryavtseva G.P., Marfunin A.S., Mikhailichenko O.A. Inclusions in diamond and diamond-bearing rocks. M.: MSU, 1991, 240 p. Garanin V.K., Kudryavtseva G.P. Mineralogy of diamond with inclusions from kimberlites of Yakutia. Izv. universities Geol. and intelligence, 1990, N 2, p. 48-56 |
| Additionally | When in powder, it burns on a platinum wire to produce carbon dioxide (CO2); when access to air is stopped and at a temperature of 1500°C, it turns into graphite. Behavior in acids. Insoluble. |
| Are you more interested in the cut version of the diamond: diamonds? Would it be better to have a diamond ring or a necklace? Then we recommend a jewelry store with a large assortment of diamond jewelry |
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Diamond – the hardest mineral, a cubic polymorphic (allotropic) modification of carbon (C), stable at high pressure. At atmospheric pressure and room temperature it is metastable, but can exist indefinitely without turning into graphite, which is stable under these conditions. In a vacuum or in an inert gas at elevated temperatures, it gradually turns into graphite.
- Structure
- Materials
- Morphology
- Origin
- Application
- Classification
- physical properties
- Optical properties
- Crystallographic properties
STRUCTURE
Crystal structure of diamond
Diamond system is cubic, space group Fd3m. The elementary cell of the diamond crystal lattice is a face-centered cube, in which carbon atoms are located in four sectors arranged in a checkerboard pattern. Otherwise, the diamond structure can be represented as two cubic face-centered lattices, offset relative to each other along the main diagonal of the cube by a quarter of its length. A structure similar to diamond is found in silicon, a low-temperature modification of tin and some other simple substances.
Diamond crystals always contain various defects in the crystal structure (point, linear defects, inclusions, subgrain boundaries, etc.). Such defects largely determine the physical properties of crystals.
PROPERTIES
Diamond can be colorless, water-transparent or colored in various shades of yellow, brown, red, blue, green, black, gray.
The color distribution is often uneven, patchy or zonal. Under the influence of X-rays, cathode and ultraviolet rays, most diamonds begin to glow (luminesce) in blue, green, pink and other colors. Characterized by exceptionally high light refraction. The refractive index (from 2,417 to 2,421) and strong dispersion (0,0574) determine the bright shine and multi-colored “play” of cut jewelry diamonds, called brilliants. The shine is strong, from diamond to greasy. Density 3,5 g/cm 3 . On the Mohs scale, the relative hardness of diamond is 10, and the absolute hardness is 1000 times higher than the hardness of quartz and 150 times that of corundum. It is the highest among all natural and artificial materials. At the same time, it is quite fragile and breaks easily. The fracture is conchoidal. Does not interact with acids and alkalis in the absence of oxidizing agents.
In air, diamond burns at 850° C with the formation of CO 2; in a vacuum at temperatures above 1.500 ° C it turns into graphite.
MORPHOLOGY
Diamond morphology is very diverse. It occurs both in the form of single crystals and in the form of polycrystalline intergrowths (“board”, “ballas”, “carbonado”). Diamonds from kimberlite deposits have only one common flat-faceted shape – the octahedron. At the same time, diamonds with characteristic curved shapes are common in all deposits – rhombic dodecahedroids (crystals similar to a rhombic dodecahedron, but with rounded edges), and cuboids (crystals with a curved shape). As experimental studies and the study of natural samples have shown, in most cases, dodecahedroid-shaped crystals arise as a result of the dissolution of diamonds by kimberlite melt. Cuboids are formed as a result of the specific fibrous growth of diamonds according to the normal growth mechanism.
Cullinan diamond broken into 9 parts
Synthetic crystals grown at high pressures and temperatures often have cube faces and this is one of their characteristic differences from natural crystals. When grown under metastable conditions, diamond easily crystallizes in the form of films and columnar aggregates.
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ORIGIN
Although diamond is metastable under normal conditions, due to the stability of its crystal structure, it can exist indefinitely without turning into a stable modification of carbon – graphite. Diamonds that are brought to the surface by kimberlites or lamproites crystallize in the mantle at a depth of 200 km. or more at a pressure of more than 4 GPa and a temperature of 1000 – 1300 ° C. In some deposits there are also deeper diamonds brought from the transition zone or from the lower mantle. Along with this, they are carried to the Earth’s surface as a result of explosive processes accompanying the formation of kimberlite pipes, 15-20% of which contain diamond.
Diamonds are also found in ultra-high pressure metamorphic complexes. They are associated with eclogites and deeply metamorphosed garnet gneisses. Small diamonds have been found in significant quantities in meteorites. They have a very ancient, pre-solar origin. They also form in large astroblemes – giant meteorite craters, where melted rocks contain significant amounts of fine-crystalline diamond. A well-known deposit of this type is the Popigai astrobleme in northern Siberia.
Diamonds are a rare, but at the same time quite widespread mineral. Industrial diamond deposits are known on all continents except Antarctica. Several types of diamond deposits are known. For several thousand years, diamonds have been mined from alluvial deposits. It was only towards the end of the 19th century, when diamond-bearing kimberlite pipes were first discovered, that it became clear that diamonds do not form in river sediments. In addition, diamonds were found in crustal rocks in associations of ultra-high pressure metamorphism, for example in the Kokchetav massif in Kazakhstan.
Both impact and metamorphic diamonds sometimes form very large deposits, with large reserves and high concentrations. But in these types of deposits, the diamonds are so small that they have no industrial value. Commercial diamond deposits are associated with kimberlite and lamproite pipes associated with ancient cratons. The main deposits of this type are known in Africa, Russia, Australia and Canada.
APPLICATION
Good crystals are cut and used in jewelry. About 15% of mined diamonds are considered jewelry, another 45% are considered near-jewelry, that is, inferior to jewelry in size, color or clarity. Currently, global diamond production is about 130 million carats per year.
Diamond (from the French brillant – brilliant), is a diamond that has been given a special shape through mechanical processing (cutting), a brilliant cut, which maximizes the optical properties of the stone such as brilliance and color dispersion.
Very small diamonds and fragments, unsuitable for cutting, are used as an abrasive for the manufacture of diamond tools necessary for processing hard materials and cutting the diamonds themselves. A cryptocrystalline variety of diamond of black or dark gray color, forming dense or porous aggregates, is called Carbonado, has a higher abrasion resistance than diamond crystals and is therefore especially valued in industry.
Small crystals are also grown artificially in large quantities. Synthetic diamonds are obtained from various carbon-containing substances, mainly from graphite, in special. apparatuses at 1200-1600°C and pressures of 4,5-8,0 GPa in the presence of Fe, Co, Cr, Mn or their alloys. They are suitable for technical use only.
| Molecular weight | 12.01 g / mol |
| Origin of the name | From Greek, adamas, meaning “invincible” or “solid”. |
| IMA status | valid, first described before 1959 (before IMA) |
CLASSIFICATION
| Strunz (8th edition) | 1/B.02-40 |
| Dana (7th edition) | 1.3.5.1 |
| Dana (8th edition) | 1.3.6.1 |
| Hey’s CIM Ref. | 1.24 |
