Structure and properties of crystals. Special physical properties of crystals
Crystals are one of the most beautiful and mysterious creations of nature. It is difficult now to name that distant year at the dawn of the development of mankind, when the attentive glance of one of our ancestors singled out among the earth's rocks small shiny stones, similar to complex geometric figures, which soon began to serve as precious jewelry.
Several millennia will pass, and people will realize that along with the beauty of natural gems, crystals have entered their lives.
Crystals are found everywhere. We walk on crystals, we build from crystals, we process crystals, we grow crystals in the laboratory, we create devices, we widely use crystals in science and technology, we are treated with crystals, we find them in living organisms, we penetrate the secrets of the structure of crystals.
The crystals that lie in the earth are infinitely diverse. The sizes of natural polyhedrons sometimes reach human growth and more. There are crystals-petals thinner than paper and crystals in layers several meters thick. There are crystals small, narrow, sharp, like needles, and there are huge, like columns. In some areas of Spain, such crystal columns are placed for the gate. The museum of the Mining Institute of St. Petersburg stores a crystal of rock crystal (quartz) more than a meter high and weighing more than a ton. Many crystals are perfectly pure and transparent like water.
Ice and snow crystals
Crystals of freezing water, that is, ice and snow, are known to everyone. These crystals cover the vast expanses of the Earth for almost half a year, lie on the tops of mountains and slide down from them as glaciers, float as icebergs in the oceans. The ice cover of a river, a mass of a glacier or an iceberg is, of course, not one big crystal. A dense mass of ice is usually polycrystalline, that is, composed of many individual crystals; they are not always distinguishable, because they are small and all grown together. Sometimes these crystals can be seen in melting ice. Each individual ice crystal, each snowflake, is fragile and small. It is often said that snow falls like fluff. But even this comparison, one might say, is too “heavy”: a snowflake is lighter than a fluff. Ten thousand snowflakes make up the weight of one penny. But, combined in huge quantities together, snow crystals can stop the train, forming snow blockages.
Ice crystals can destroy an aircraft in a matter of minutes. Icing - a terrible enemy of aircraft - is also the result of crystal growth.
Here we are dealing with the growth of crystals from supercooled vapors. IN upper layers atmosphere, water vapor or water droplets, can be stored for a long time in a supercooled state. Supercooling in the clouds reaches -30. But as soon as a flying plane breaks into these supercooled clouds, the same hour begins a violent crystallization. Instantly, the plane is covered with a pile of rapidly growing crystals.
Gems
From the earliest times of human culture, people have valued beauty precious stones. Diamond, ruby, sapphire and emerald are the most expensive and favorite stones. They are followed by alexandrite, topaz, rock crystal, amethyst, granite, aquamarine, chrysolite. Sky-blue turquoise, delicate pearls and iridescent opal are highly valued.
Healing and various supernatural properties have long been attributed to precious stones, and numerous legends have been associated with them.
Precious stones served as a measure of the wealth of princes and emperors.
In the museums of the Moscow Kremlin, you can admire a rich collection of precious stones that once belonged to royal family and a small group of rich people. It is known that the hat of Prince Potemkin - Taurida was so studded with diamonds and because of this it was so heavy that the owner could not wear it on his head, the adjutant carried the hat in his hands behind the prince.
Among the treasures of the diamond fund of Russia is one of the greatest and most beautiful diamonds in the world "Shah".
The diamond was sent by the Shah of Persia to the Russian Tsar Nicholas I as a ransom for the murder of the Russian ambassador Alexander Sergeevich Griboedov, the author of the comedy Woe from Wit.
Our homeland is rich in gems than any other country in the world.
Crystals in the Universe
There is not a single place on Earth where there would be no crystals. On other planets, on distant stars, crystals constantly arise, grow and collapse.
In space aliens - meteorites there are crystals known on Earth, and not found on Earth. In a huge meteorite that fell in February 1947 in the Far East, crystals of nickel iron several centimeters long were found, while under terrestrial conditions the natural crystals of this mineral are so small that they can only be seen with a microscope.
2. Structure and properties of crystals
2. 1 What are crystals, crystal forms
Crystals form at a fairly low temperature when thermal motion so slowly that it does not destroy a certain structure. characteristic feature solid state of matter is the constancy of its form. This means that its constituent particles (atoms, ions, molecules) are rigidly interconnected and their thermal motion occurs as an oscillation around fixed points that determine the equilibrium distance between the particles. The relative position of the equilibrium points in the entire substance must provide a minimum of energy for the entire system, which is realized with their certain ordered arrangement in space, that is, in a crystal.
A crystal, according to the definition of G. W. Wulff, is a body limited due to its internal properties by flat surfaces - faces.
Depending on the relative sizes of the particles that form the crystal and the type of chemical bond between them, the crystals have a different shape, determined by the way the particles are connected.
In accordance with the geometric shape of crystals, the following crystal systems exist:
1. cubic (many metals, diamond, NaCl, KCl).
2. Hexagonal (H2O, SiO2, NaNO3),
3. Tetragonal (S).
4. Rhombic (S, KNO3, K2SO4).
5. Monoclinic (S, KClO3, Na2SO4*10H2O).
6. Triclinic (K2C2O7, CuSO4*5 H2O).
2.2 Physical properties of crystals
For a crystal of this class, one can specify the symmetry of its properties. So cubic crystals are isotropic with respect to light transmission, electrical and thermal conductivity, thermal expansion, but they are anisotropic with respect to elastic, electrical properties. The most anisotropic crystals of low syngonies.
All properties of crystals are interconnected and are determined by the atomic - crystal structure, the bonding forces between atoms and the energy spectra of electrons. Some properties, for example: electrical, magnetic and optical, depend significantly on the distribution of electrons over energy levels. Many properties of crystals depend decisively not only on symmetry, but also on the number of defects (strength, plasticity, color, and other properties).
Isotropy (from the Greek isos - equal, the same and tropos - turn, direction) independence of the properties of the medium from the direction.
Anisotropy (from the Greek anisos - unequal and tropos - direction) is the dependence of the properties of a substance on direction.
Crystals are populated with many different defects. Defects, as it were, enliven the crystal. Due to the presence of defects, the crystal reveals a "memory" of the events in which it became or when it was, the defects help the crystal "adapt" to the environment. Defects qualitatively change the properties of crystals. Even in very small quantities, defects greatly affect those physical properties, which are completely or almost absent in an ideal crystal, being, as a rule, "energetically favorable", defects create around themselves areas of increased physical and chemical activity.
3. Growing crystals
Growing crystals is an exciting activity and, perhaps, the simplest, most accessible and inexpensive for beginner chemists, as safe as possible in terms of TB. Careful preparation hones skills in the ability to carefully handle substances and properly organize the plan of their work.
Crystal growth can be divided into two groups.
3.1 Natural crystal formation in nature
Crystal formation in nature (natural crystal growth).
More than 95% of all rocks of which it is composed Earth's crust, were formed during the crystallization of magma. Magma is a mixture of many substances. All these substances different temperatures crystallization. Therefore, during cooling, the magma is divided into parts: the first crystals of the substance with the highest crystallization temperature appear and begin to grow in the magma.
Crystals are also formed in salt lakes. In summer, the water of the lakes quickly evaporates and salt crystals begin to fall out of it. Lake Baskunchak alone in the Astrakhan steppe could provide many states with salt for 400 years.
Some animal organisms are "factories" of crystals. Corals form whole islands, built from microscopic crystals of carbonic lime.
The pearl gemstone is also built from crystals that the pearl mussel produces.
Gallstones in the liver, kidney stones and bladder stones that cause serious human diseases are crystals.
3.2 Artificial crystal growth
Artificial growth of crystals (growing of crystals in laboratories, factories).
Growing crystals is a physical and chemical process.
The solubility of substances in different solvents can be attributed to physical phenomena, since the destruction of the crystal lattice occurs, heat is absorbed in this case (an exothermic process).
There is also a chemical process - hydrolysis (reaction of salts with water).
When choosing a substance, it is important to consider the following facts:
1. The substance must not be toxic
2. The substance must be stable and chemically pure enough
3. The ability of a substance to dissolve in an available solvent
4. The resulting crystals must be stable
There are several methods for growing crystals.
1. Preparation of supersaturated solutions with further crystallization in an open vessel (the most common technique) or a closed one. Closed - an industrial method, for its implementation a huge glass vessel with a thermostat simulating a water bath. The vessel contains a solution with a ready-made seed, and every 2 days the temperature drops by 0.1°C; this method makes it possible to obtain technologically correct and pure single crystals. But it requires high costs electricity and expensive equipment.
2. Evaporation of a saturated solution open way when the gradual evaporation of a solvent, for example, from a loosely closed vessel with a salt solution, can itself give rise to crystals. Closed way involves keeping the saturated solution in a desiccator over a strong desiccant (phosphorus(V) oxide or concentrated sulfuric acid).
II. Practical part.
1. Growing crystals from saturated solutions
The basis for growing crystals is a saturated solution.
Instruments and materials: 500 ml glass, filter paper, boiled water, spoon, funnel, salts CuSO4 * 5H2O, K2CrO4 (potassium chromate), K2Cr2O4 (potassium dichromate), potassium alum, NiSO4 (nickel sulfate), NaCl (sodium chloride), C12H22O11 (sugar).
To prepare a salt solution, we take a clean, well-washed glass of 500 ml. pour hot (t=50-60C) boiled water 300ml into it. pour the substance into a glass in small portions, mix, achieving complete dissolution. When the solution is "saturated", that is, the substance will remain at the bottom, add more substances and leave the solution at room temperature for a day. To prevent dust from getting into the solution, cover the glass with filter paper. The solution should turn out to be transparent, an excess of the substance in the form of crystals should fall out at the bottom of the glass.
Drain the prepared solution from the precipitate of crystals and place in a heat-resistant flask. There also put a little chemically pure substance (precipitated crystals). Heat the flask in a water bath until completely dissolved. The resulting solution is still heated for 5 minutes at t = 60-70C, poured into a clean glass, wrapped in a towel, left to cool. After a day, small crystals form at the bottom of the glass.
2. Creation of the presentation "Crystals"
We take pictures of the resulting crystals, using the capabilities of the Internet, we prepare a presentation and a collection of "Crystals".
Making a picture using crystals
Crystals have always been famous for their beauty, which is why they are used as jewelry. They decorate clothes, dishes, weapons. Crystals can be used to create paintings. I painted the landscape "Sunset". Grown crystals are used as a material for making the landscape.
Conclusion
In this paper, only a small part of what is known about crystals at the present time was told, however, this information also showed how extraordinary and mysterious crystals are in their essence.
In the clouds, on the tops of mountains, in sandy deserts, seas and oceans, in scientific laboratories, in plant cells, in living and dead organisms - we will meet crystals everywhere.
But maybe the crystallization of matter takes place only on our planet? No, we now know that on other planets and distant stars, crystals are continually arising, growing and breaking down. Meteorites, space messengers, also consist of crystals, and sometimes they include crystalline substances that are not found on Earth.
Crystals are everywhere. People are used to using crystals, making jewelry out of them, admiring them. Now that the methods of artificial growth of crystals have been studied, the scope of their application has expanded, and perhaps the future the latest technologies belongs to crystals and crystalline aggregates.
It was not until the 17th century that modern humanity rediscovered crystals for itself. The birth date of crystallography, the science that studies crystals, is considered to be 1669.
Although scientific crystallography originated in the 17th century, theoretical basis about the structure of crystals and methods for their study were laid down only in the 19th century. In the 20th century, these discoveries found practical implementation in various areas of human life. Crystals have become widely used in various fields of science and technology. The future is also theirs.
Crystals surround us from all sides. They are the basis physical world. Almost all minerals are composed of them, including basalt, granite, limestone and marble. All metals and most non-metals are composed of them: rubber, bones, hair, cellulose and much more.
We live in a world of crystals. Houses, boats, buses, planes, rockets, knives and forks... everything is made up of them.
Even in food we consume crystalline substances: salt, sugar, not to mention the medicines in tablets and powders that we take during illness.
There is no place on Earth where there would be no crystals. Yes, and in the universe they are widespread, as they serve as its material basis.
In 1669, the Danish physician N. Stenon made an important discovery, he found that in crystals formed by the same substance, the angles between adjacent faces are always the same, regardless of the shape and size of the crystal.
This means that each crystal has its own unique angle between the faces.
This discovery entered crystallography as the law of constancy of angles. Thus, if the angle between the faces is known, then it is possible to determine the substance of the crystal without resorting to chemical or physical analysis. One need only compare them with the angles of known crystals.
In addition, the same Stenon was the first to propose a remarkable version that crystals do not grow from the inside, as is observed in plants, but from the outside, by superimposing new particles on the outer planes.
Crystals are made up of atoms, ions and molecules. These particles are arranged strictly certain order, forming a spatial lattice. Atoms and ions are held in them by forces of attraction and repulsion. They do not stand still, but constantly fluctuate.
Each crystal has its own characteristic shape, which depends not only on the environment in which he grew up, but also on the structure of the spatial lattice. The shape of the lattice also determines the properties of the crystal itself. In this regard, the most indicative example is diamond and graphite, spatial lattices, which are formed by atoms of the same element - carbon.
Graphite is a black mineral, soft and ductile, conducts electricity and resistant to fire. And all because its lattice consists, as it were, of layers, the connection between which is not as strong as between individual atoms within this layer. Such layers are easy to move one relative to the other with light pressure, which is what we observe when we write with a pencil. He, as we have already guessed, is graphite.
But diamond is the exact opposite of graphite. It is transparent, surpasses other crystals in strength, but does not conduct current and burns easily in a stream of oxygen. It is almost twice as heavy as graphite. "Guilty" in all this is his spatial lattice. It is three-dimensional, and each atom in it is tightly connected to four others.
Crystals are solids and can be liquid if their molecules have the ability to orient themselves in one direction "all of a sudden" or in groups-layers or in other ways.
Finally, "crystals" can be purely energetic, invisible, but the science of crystallography has not yet dealt with such "ghosts".
In a crystal, faces intersect at edges, and edges intersect at vertices. Faces, edges and vertices - required elements faceting.
The main features of crystals are uniformity and flatness. Thus, if the crystals have flat faces, then their composition is homogeneous. And vice versa: if the substance of the crystal is homogeneous, then it has flat faces.
Crystals can make sounds, such as singing sands. This phenomenon attracts the attention of a traveler who finds himself among the sand dunes of the Karakum desert or other deserts.
Suddenly, from nowhere, indistinct sounds of singing are heard, but there is no one around, only sands. They make sounds when a sandy slope begins to slide in a light wind.
Singing sands are not only found in deserts. Harmonious melodies often arise when walking on wet sand on the beach.
Russian traveler A. Eliseev left his impressions of the Sahara:
"... some enchanting sounds were heard in the hot air, rather high, melodious, not without harmony, with a strong metallic tint. They were heard from everywhere, as if they were produced by invisible desert spirits ...
The desert was silent, but the sounds flew and melted in the hot atmosphere, arising from somewhere above and disappearing as if in the ground... Now cheerful, now compassionate, now sharp and noisy, now tender and melodic, they seemed to be the speech of living beings, but not the sounds of a dead desert...
No nymphs of the ancients could think of anything more amazing and wonderful than these mysterious songs of the sands.
Everyone who has heard the songs of the sands is surprised by this phenomenon, and many have tried to explain it. For example, the ancient Egyptians believed that such sounds were the product of desert spirits, and they were right.
Modern scientists believe that the reason for the appearance of sounds may be hidden in the very structure of a grain of sand. It is known to contain a lot of quartz and other silicas.
Quartz is the most common silicon oxide in the earth's crust. Its crystals have a number of outstanding properties. They are rich in simple, that is, closed, closed forms. Here you can find pyramids, prisms, rhombohedrons - more than five hundred simple forms. Quartz is characterized by the formation of twins - symmetrical intergrowths of crystals.
But not only diversity external forms surprising quartz. Its crystal does not have a center of symmetry, which is a sure sign that it has piezoelectric properties.
Therefore, if a crystal is compressed, then on its faces perpendicular to the direction of compression, opposite electric charges arise: positive - on one face, negative - on the other.
So mechanical energy with the help of a quartz crystal is converted into electrical energy. If we remove the mechanical load from the crystal and begin to stretch it, then the polarity of the charges on the faces changes to opposite charges. And this happens in a quartz crystal, which itself is an insulator!
This phenomenon in quartz crystals was discovered in 1817 by the French crystallographer R. Gayuy, and again in 1880 by the French scientists, brothers Jean and Pierre Curie, and was called piezoelectricity. Later, they also discovered the reversibility of this effect.
It turned out that a quartz crystal could be compressed or stretched if opposite electric charges were created on its faces. In this case, electrical energy was converted into mechanical energy.
It is this property of the crystal that gives reason to believe that the singing of the desert sands is associated with the sojourn of spirits. Since the spirits of the desert are demonic entities that represent the chaotic movement of electrons.
Demonic entities lack core and magnetism. They represent a void that is surrounded by randomly moving electrons. Thus, demonic entities are carriers of an electric charge, which causes voltage on the surface of crystal molecules.
As a result of this impact, the sand crystals are compressed and unclenched, causing the air to vibrate, which manifests itself in the form of sounds.
The singing of the sands has a strong effect on the human psyche, causing instinctive fear. The reason for this fear can be explained by the fact that the human soul, in the singing of the sands, catches the "breath" of death, the bearer of which is a demonic essence.
Man, animal and plant, as living organisms, cannot, like a demonic entity, endure tension and influence crystals, cannot cause sand to sing. Since the atomic system of living cells of organic bodies produces vibrations of a different frequency and electromagnetic induction, which makes the body system closed in terms of electrical action. That is, the body's electrical energy is captured by its own magnetic field, which controls it.
And only in the case when the spirituality of a person falls, which reduces the potential magnetic field his body, may form an excess electrical energy and extra stress. It is this tension that the demonic force captures and endures. This excess of electricity negatively affects first of all the crystalline structures of the human organism itself, and then the crystalline bodies that surround it. For example, on Jewelry worn by the person. Therefore, in ancient times, according to the state of amulet stones, they predicted the state of human health and even their future. Pay attention to milk, which is sensitive to the presence in the house evil spirits.
As a result of research, it was found that quartz in the form of a plate cut out of a crystal body has such great elasticity that it can oscillate at a very high frequency, successively compressing and stretching when changing polarity electric field.
Quartz can vibrate over a wide range of frequencies, creating acoustic and electrical waves, that is, singing. When a sand avalanche slides down from a dune or a sand mass collapses, the underlying layers of sand experience variable pressure from the moving layer. They compress under pressure and "straighten" when the pressure is reduced. The quartz crystals present in the grains of sand begin to oscillate, vibrate, generating acoustic waves. Similar processes occur when walking on wet sand.
Mechanical vibrations of quartz crystals in sand grains lead to the formation electric charges on their faces, the polarity of which changes synchronously with the mechanical vibrations of the crystals. There are not only acoustic waves, but also alternating electric field certain frequency spectrum.
Each grain of sand, each crystal sings its own song at its own frequency. Their voices add up. And now polyphonic singing sounds, loud enough, the frequency range is wide. It is what the human ear hears. But only low frequencies. High frequencies our ear does not perceive. When the movement of the sand stops, the excited mechanical and electrical vibrations of the quartz crystals in the grains of sand fade, and the sound stops.
In 1957, the Soviet scientist K. Baransky found that acoustic waves can be excited directly on the surface of a crystal, which further expanded the range of generated frequencies. Then American scientists increased the frequency ceiling by another order of magnitude.
If the sands sing when they are subjected to mechanical and electrical influences, then the Earth itself sings for a similar reason. The pulsating fiery heart of the planet, the influence of other planets and the Sun cause movement and vibration of the rocks of the earth's crust, making the Earth sound. Her song, not perceived by the human ear, is carried far in space.
The earth's crust is in constant tension. Here and there, earthquakes and volcanic eruptions occur, freeing dangerous zones from the overload of demonic entities on them - spiritless voids.
The number of earthquakes on Earth reaches up to one hundred thousand a year. From total number earthquakes strong earthquakes occur up to a thousand a year.
From the centers of deformation of the earth's crust, vibrations are transmitted over long distances. Wave propagation speed is very high. In granite rocks for longitudinal waves it is more than 5000 meters per second, for transverse - about 2509 meters per second.
On their way, earth waves either compress rocks or stretch them, causing the formation of powerful electric charges of different polarity. They are especially large in the epicenter of compression or extension, where the earth's rocks experience very strong, up to rupture, deformations.
Electric discharges in the form of the strongest underground lightning rapidly spread through zones of least resistance and often break through from the depths to the surface of the Earth, leaving melted solid rocks or strange round holes.
There is nothing strange in the fact that the Earth sounds. Its hard rocks, basalt, granites, sandstones and others have a crystalline structure. They contain many quartz formations. When crystals are deformed, not only acoustic and electric waves arise, but other physical and chemical processes also occur along the way.
Terrible rumble of deep storms "hear" many animals, birds, insects. They can even be "annunciators" of an approaching underground strike. And only a person, as a rule, is caught unawares. Since he stopped perceiving himself as a part of nature and to follow the ongoing processes in nature.
In addition to "singing", crystals vibrate in a certain range of the light spectrum, so they acquire their own color, for example, jewelry stones. The stones are transparent and with a strong luster capable of transmitting and modifying radiant energy. The color of minerals is associated with the inclusion in their crystal lattice of metal ions that easily change their valence and are capable of giving up their electrons with a minimum supply of energy.
Some of these electrons "wander" among the atoms of the crystal lattice, interacting with them, exchanging energy with them. As a result, local disturbances of the crystal lattice arise in the crystal and continuously change their pattern. Thus, the crystal intensively lives its "inner life", the external manifestations of which make up the sets of "magic" properties of stones-amulets.
Iron, copper, manganese, chromium, and rare earth elements belong to such metals, impurities of compounds, which noticeably change the energy silhouette of the crystal.
Crystals and their properties
Depending on the internal structure, crystalline and amorphous solid bodies.
crystalline call solids formed from geometrically correctly located in space material particles - ions, atoms or molecules. Their ordered, regular arrangement forms a crystal lattice in space - an endless three-dimensional periodic formation. It distinguishes nodes (individual points, centers of gravity of atoms and ions), rows (a set of nodes lying on one straight line) and flat grids (planes passing through any three nodes). geometrically correct crystal form due primarily to their strictly natural internal structure. The grids of the crystal lattice correspond to the faces of a real crystal, the intersections of the grids - rows - to the edges of the crystals, and the intersections of the edges - to the tops of the crystals. Most known minerals and rocks, including stone building materials, are crystalline solids.
All crystals have a number of things in common. basic properties.
Uniformity of the structure- same pattern relative position atoms in all parts of the volume of its crystal lattice.
Anisotropy- the difference in the physical properties of crystals (thermal conductivity, hardness, elasticity, and others) in parallel and non-parallel directions of the crystal lattice. The properties of crystals are the same in parallel directions, but not the same in non-parallel ones.
The ability to self-limit, i.e. take the form of a regular polyhedron with the free growth of crystals.
Symmetry- the possibility of combining a crystal or its parts by certain symmetrical transformations corresponding to the symmetry of their spatial lattices.
Amorphous or mineraloids are called solids, characterized by a disorderly, chaotic (as in a liquid) arrangement of its constituent particles (atoms, ions, molecules), for example, glass, resins, plastics, etc. An amorphous substance is distinguished by its isotropic properties, the absence of a clearly defined temperature melting and natural geometric shape.
The study of the crystalline forms of minerals has shown that the world of crystals is distinguished by symmetry, which is well observed in the geometric shape of their cut.
An object is considered symmetrical if it can be combined with itself by certain transformations: rotations, reflections in the mirror plane, reflection in the center of symmetry. Geometric images (auxiliary planes, straight lines, points), with the help of which alignment is achieved, are called symmetry elements. These include axes of symmetry, planes of symmetry, center of symmetry (or center of inversion).
The center of symmetry is a special point inside the figure, when drawn through which any straight line will meet at an equal distance from it the same and opposite parts of the figure. The plane of symmetry is an imaginary plane that divides a figure into two equal parts so that one of the parts is a mirror image of the other. The axis of symmetry is an imaginary straight line, when rotated around it at some specific angle, the same parts of the figure are repeated.
Minerals characterized by a crystalline structure have certain type crystal lattice, the particles in which are held by chemical bonds. Based on the concept of valence electrons, there are four main types of chemical bonds:
1) ionic or heteropolar (mineral halite),
2) covalent or homeopolar (mineral-diamond),
3) metallic (mineral-gold),
4) molecular or van der Waals. The nature of the bond affects the properties of crystalline substances (brittleness, hardness, malleability, melting point, etc.). A single type of bond (homodesmic structure) or several types (heterodesmic structure) can be present in a crystal.
Natural crystals... They are also called beautiful, rare stones or solids. We imagine a crystal stone as a large, bright, transparent or colorless polyhedron with perfect shiny edges. In life, we often meet such solid substances in the form of grains of irregular shape, grains of sand, fragments. But their properties are the same as those of perfect large crystals. Plunge with us into the magical world natural stones crystals, get acquainted with their structure, forms, types. Well, let's go...
Mystery of crystals
The world of crystals is beautiful and mysterious. Multi-colored pebbles have attracted and attracted us with their beauty since childhood. We feel their mystery on an intuitive level and admire their natural beauty. People have always wanted to know as much as possible about natural solids, about the properties of crystals, the formation of their forms, growth and structure.
The world of these stones is so unusual that you want to look inside them. What will we see there? A picture of endlessly stretching, strictly ordered rows of atoms, molecules and ions will open before your eyes. All of them strictly obey the laws that rule in the world of crystal stones.
Crystalline substances are very widespread in nature, because all rocks are composed of them. The entire earth's crust is made up of rocks. It turns out that these unusual substances can even be grown at home yourself. It is important to note that "crystal" in ancient Greek meant "ice" or "rock crystal".
What is a crystal stone?
What do school textbooks say about crystals? They say that these are solid bodies that are formed under the influence of natural or laboratory conditions and have the appearance of polyhedra. The geometric structure of these bodies is infallibly strict. The surface of crystalline figures is made up of perfect planes - faces that intersect along straight lines, which are called edges. Vertices appear at the intersection points of edges.
The solid state of matter is the crystal. It has a certain shape, a specific number of faces, depending on the arrangement of atoms. So, solids, in which molecules, atoms, ions are arranged in a strict pattern in the form of nodes of spatial lattices.
We most often associate crystals with rare and beautiful gemstones. And this is not in vain, diamonds are also crystals. But not all solids are rare and beautiful. After all, particles of salt and sugar are also crystals. There are hundreds of substances around us in the form of them. One of these bodies is considered to be frozen water (ice or snowflakes).
Formation of various forms of crystals
In nature, minerals are formed as a result of rock-forming processes. Solutions of minerals in the form of hot and molten rocks lie deep underground. When these hot rocks are pushed to the surface of the earth, they cool down. Substances cool very slowly. Minerals form crystals in the form of solids. For example, minerals of quartz, feldspar and mica are present in granite.
Each crystal contains a million individual elements (monocrystals). A cell of a crystal lattice can be represented as a square with atoms at the corners. These can be oxygen atoms or other elements. It is known that crystals can react to various energies, remember people's attitude towards them. That is why they are used for healing and cleansing. Crystals can be of various shapes. Depending on this, they are divided into 6 large types.
Different types and types of natural solids
Crystal sizes can also be different. All solids are divided into ideal and real. Ideal bodies are those with smooth edges, strict long-range order, a certain symmetry of the crystal lattice, and other parameters. Real crystals include those that are found in real life. They may contain impurities that lower the symmetry of the crystal lattice, the smoothness of the faces, and the optical properties. Both types of stones are united by the rule for the arrangement of atoms in the above lattice.
According to another criterion for dividing them, they are divided into natural and artificial. For the growth of natural crystals, natural conditions are needed. Artificial solids are grown in the laboratory or at home.
According to the aesthetic and economic criterion, they are divided into precious and non-precious stones. Precious minerals are rare and beautiful. These include emerald, diamond, amethyst, ruby, sapphire and others.
The structure and forms of accumulations of solids
One-peak crystals are hexagonal stones with a pyramidal top. The base of such generator minerals is wider. There are crystals with two peaks - Yin and Yang. They are used in meditation to balance the material and spiritual principles.
Minerals, in which 2 of the 6 faces on the side are wider than all the others, are called lamellar. They are used for telepathic healing.
Crystals formed as a result of impacts or cracks, which then decompose into 7 shades, are called iridescent. They relieve depression and frustration.
Minerals with various inclusions of other elements are called ghost crystals. First, they stop growing, then other materials settle on them, and then growth around them resumes again. Thus, the contours of a mineral that has stopped growing are visible, so it appears ghostly. Such crystals are used to attract crops in garden plots.
Unusual Druzes
The Druze are a very beautiful sight. This is a collection of many crystals on one base. They have positive and negative polarity. They clean the air and recharge the atmosphere. Druses of quartz, emerald, topaz are found in nature. They bring peace and harmony to a person.
Druse is also called intergrown crystals. Most often, garnets, pyrites, and fluorites are subject to this phenomenon. They are often exhibited as exhibits in museums.
Small intergrown crystals are called a brush, large minerals are called a flower. Very beautiful variety Druze are geodes. They grow on the walls. Druses can be very small and large. These are very valuable finds. Druses of agate, selenite, amethyst, citrine, morion are highly valued.
How do crystals store information and knowledge?
Scientists have found that there are triangles on the edges of the crystals, indicating the presence of knowledge in them. This information can only be obtained certain person. If such a person appears, then the stones will give him their true insides.
Crystals are able to transmit vibrations, awaken higher power consciousness, balance mental strength. Therefore, they are often used in meditation. Previous civilizations stored information in stones. For example, rock crystal was considered the gem of the gods. Crystals were revered as living beings. Even "cosmos" originally meant "precious stone".
Gems
It is important to note that precious crystals in their raw form are not all that beautiful. They are also called stones or minerals. They are called precious because they are very beautiful in cutting and are used in jewelry. Many are familiar with amethysts, diamonds, sapphires, rubies.
Diamond is considered the hardest stone. A fragile crystal of a grassy green color - an emerald. Ruby is a red variety of corundum. Deposits of this crystal exist on almost all continents. What is considered his undeniable ideal? Burmese rubies. Ruby deposits in the Russian Federation are located in the Chelyabinsk and Sverdlovsk regions.
What other expensive minerals are there? Transparent precious crystals of various colors - from pale blue to dark blue - are sapphires. Although it is a rare mineral, it is valued below ruby.
An expensive variety of quartz is the beautiful gemstone amethyst. Once it was inserted by the high priest Aaron into the number of 12 stones of his pectoral. Amethyst has a beautiful purple or lilac tint.
Russian diamonds
So, the hardest crystal - diamond - is mined from kimberlite pipes formed as a result of eruptions of underground volcanoes. The crystal lattice of this stone is formed under the influence of high temperature And high pressure carbon.
Diamond mining in Russia began in Yakutia only in the middle of the last century. Today, the Russian Federation is already among the leaders in the extraction of these precious stones. Billions of rubles are allocated annually for diamond mining in Russia. It is worth noting that there are several carats of diamonds per ton of kimberlite pipes.
Crystals of substances have unique physical properties:1. Anisotropy is the dependence of physical properties on the direction in which these properties are determined. Feature only single crystals.
This is explained by the fact that crystals have a crystal lattice, the shape of which causes a different degree of interaction in different directions.
Thanks to this property:
A. Mica delaminates into plates in only one direction.
B. Graphite is easily torn into layers, but one single layer is incredibly strong.
B. Gypsum conducts heat differently in different directions.
D. A ray of light hitting a tourmaline crystal at different angles gives it different colors.
Strictly speaking, it is anisotropy that determines the formation of a form by a crystal that is specific for a given substance. The fact is that due to the structure of the crystal lattice, the growth of the crystal occurs unevenly - in one place faster, in another much slower. As a result, the crystal takes shape. Without this property, the crystals would grow spherical or even completely of any shape.
This also explains not correct form polycrystals - they do not have anisotropy, since they are an intergrowth of crystals.
2.
Isotropy is a property of polycrystals, the opposite of anisotropy. Only polycrystals have it.
Since the volume of single crystals is much less than the volume of the entire polycrystal, all directions in it are equal.
For example, metals equally conduct heat and electric current in all directions, since they are polycrystals.
Without this property, we would not be able to build anything. Majority building materials are polycrystals, so no matter which way you turn them, they will withstand everything. Single crystals can be superhard in one position and very brittle in another.
3. Polymorphism - the property of identical atoms (ions, molecules) to form different crystal lattices. Due to different crystal lattices, such crystals can have completely different properties.
This property causes the formation of some allotropic modifications simple substances, for example, carbon is diamond and graphite.
Diamond properties:
· High hardness .
· Does not conduct electricity.
· Burns in a stream of oxygen.
Graphite properties:
· soft mineral.
· Conducts electricity.
· It is used to make refractory clay.
