Where is mica mined? Mica - rock

Mica is a group of layered silicates of volcanic origin formed by crystallization. Some species appeared during the metamorphism of rocks. Distinctive characteristics are the layered structure and high cleavage.

They have the general formula:

R1(R2)3 (OH, F)2, where R1 = K, Na; R2 = Al, M, Fe, Li.

Mica has been known since ancient times. She was used in Ancient Egypt, Roman Empire, Greece, China and other states. It was used in the manufacture of household items, window frames were made from it, and it was used for interior decoration of temples.

In Russia, the mineral is mined in the north of the country and Siberia: Karelia, the Kola Peninsula, Yakutia, the Irkutsk region. The world's largest suppliers are also the United States, Canada, India, South Africa and Brazil. The extraction of minerals takes place both open-pit and underground. The most popular mica-bearing minerals are muscovite, phlogopite, and vermiculite. Muscovite occupies 90% of world production, only 10% falls on the rest.

Varieties of mica

Depending on the chemical elements, which are part of mica-bearing minerals, the following varieties are distinguished:

aluminum - paragonite and muscovite;
iron-magnesium - biotite, phlogopite and lepidomelane;
lithium - zinnwaldite, lepidolite and tainiolite.

The most common are four types: muscovite, biotite, phlogopite, lepidolite.

Muscovite is a transparent or whitish mineral that can change color and take on shades of yellow, pink or green if impurities are present. Biotite has a large amount of iron in its composition, so it is opaque, its color varies from brown and green to completely black. Phlogopite is different a high degree transparency, has a yellowish or brown tint. Lepidolite is characterized by a heterogeneous color, the color range of the mineral is quite wide - from gray and yellow to lilac and purple.

Aluminum micas are used in radio engineering and electrical engineering as an electrical insulating material. Lithium has excellent optical properties, so they are used in the glass industry for the manufacture of glasses. Iron-magnesium are used as insulators in the production of industrial and household items.

There is another classification of mica-bearing minerals, depending on their use in industry. Industrial mica is divided into:

sheet;
vermiculite;
small and scrap.

Sheet is an excellent electrical insulator and heat conductor. It is these properties that are used most often.

Vermiculite is obtained by hydrolysis. It is most often used as a thermal insulation material. Scrap is a waste from the production of larger sheets, used in chemical industry and construction.

Physical and chemical properties

The properties of the mineral are largely due to its layered structure. First of all, the following distinguishing features can be distinguished:

high cleavage;
flexibility;
elasticity;
strength;
the dielectric constant.

Different types of mica have different Chemical properties on which its use largely depends. Thus, muscovite has a heat resistance of 400 - 700 ºС, and phlogopite - 200 - 800 ºС. The density of muscovite is 2.6 - 2.8, phlogopite - 2.3 - 2.8. The coefficient of thermal expansion for muscovite is 19.8, for phlogopite it is 18.3. The melting point also depends on the chemical composition and varies between 1,140 and 1,400 degrees.

The physical and chemical properties of mica determine the scope of its application. It is widely used both in industry and in everyday life.

Scope of application

Engineering. Mica is an excellent insulator, even with very strong heating, it does not change its characteristics. Due to this quality, it is used in electronics in the manufacture of various devices, in shipbuilding and aircraft construction. It is used in the manufacture household appliances such as microwave ovens. Also, mica plates are part of navigation equipment, optical filters and heating devices.

Construction. For many years, mica has been constantly used in construction. In this area, expanded vermiculite is most often used. It is used as a heat insulating material. Vermiculite does not cake and does not lose its qualities over the years. In addition, mica-bearing minerals are part of some cement mixtures and rubber materials.

Chemical industry. Thanks to new technologies and modern methods processing, it is possible to obtain new materials from already known minerals. Mica is found in many paints and plastics, and is used to make synthetic materials such as mica for flowers. It is actively used by designers to create original compositions.

Agriculture. Vermiculite is used in crop and animal husbandry. AT agriculture it is used for aeration and mulching of the soil. It is also used for growing plants on artificial media. Thanks to its high water absorption coefficient, it creates optimal conditions for plant growth and improves soil structure. In addition, it is used in the production of various animal fillers.

Furniture production and interior items. Mica is used for interesting decoration of furniture and creation of original interior compositions. Even in pre-revolutionary Russia, wonderful jewelry boxes and small chests for household trifles were made from them, furniture doors and window frames were made. And today it is used to decorate furniture and interior items, it is also used in the production of many wallpapers and decorative plasters.

Cosmetology and medicine. Mica is an ingredient in many cosmetics. In particular, it is used in the production of blush, eye shadow and powder. It gives cosmetics a pearly sheen and makes the skin radiant and healthy. It is also used in medicine in the manufacture of various optical instruments and electronics. The mineral is extremely popular in alternative medicine. For example, black mica is a very important mineral in Ayurveda and is used to treat many diseases.

Since ancient times, mica has been actively used by man in Everyday life for the manufacture of various substances, materials and household items. Its scope is extremely wide to this day. Despite the appearance a large number synthetic materials, it is still actively mined all over the world. Her unique properties along with environmental friendliness make mica a sought-after mineral in various industries and the national economy.

The most common are muscovite, biotite, phlogopite, lepidolite. Since these names are rather difficult to pronounce and remember, they are called by one general term - mica. All micas are similar in structure, although they contain various metals. Mica is very soft and tends to split into very thin translucent layers that have a smooth surface. Mica is a transparent crystalline mineral, it can be pearly, matte and shiny. Mica comes in different colors: yellow, green, red, brown and black, or it can just be transparent and colorless. To obtain new shades, mica is mixed with iron oxides.

Mica occurs in the earth's crust and belongs to volcanic rocks. formed as a result of the cooling of molten lava. But in some cases, it originated from other minerals as a result of metamorphism - the process of mineral and structural changes in rocks under the influence of temperature, pressure and water. For example, muscovite is very often formed as a result of the alteration of aluminum minerals.

Mica is mined in mines in the form of thin layers. The leaders in mica mining are the USA, Canada, India, Brazil, Madagascar, Namibia and Russia. In Russia, mica deposits are located in the Irkutsk region, Karelia, Transbaikalia, Yakutia, Taimyr and Kola Peninsula.

AT industrial production mica is stratified and cut into pieces of the desired size and various thicknesses. Sheet mica has good electrical insulating properties, it does not conduct heat and electricity. Therefore, it is widely used in radio electronics, in the production of fire-resistant materials and electrical equipment. In shipbuilding, mica is used in portholes and in the construction of yachts. Fine-flake mica is used to make thermal insulation materials, and is also used as a sorbent in agriculture.

Mica is also used as a decorative material. When restoring items of decorative and applied art from expensive breeds wood or ivory mica is used along with foil and mother-of-pearl.

Currently, mica is widely used in cosmetology in the production of mineral cosmetics. It is added to powders, blush, shadows, which gives the skin radiance, makes it smoother and brighter.

And mica has a rich history. AT XVI-XVII centuries windows in royal palaces, merchant and boyar houses, churches were covered with mica. At that time in Russia it was called "crystal" and "Moscow glass". The craftsmen connected together many pieces of mica of different sizes, thus creating mica windows. They were decorated with various images or ornaments. In the 17th century, mica windows were painted with paints and depicted on them grass and flowers, animals and birds. The mica windows of that time can be called the Russian analogue of Western European stained-glass windows. Daylight, penetrating through such multi-colored windows, created a special, joyful mood and made the interior more comfortable. In lamps and lanterns, mica plates served as windows that blocked open fire. Exquisite doors for storage boxes for clothes and fabrics, jewelry boxes and business papers were also made of mica. Mica was also widely used for the decoration of churches and for the creation of icons.

Mica mining was one of the important Russian crafts. It was expensive, from fifteen to one hundred and fifty rubles per pood, depending on the variety, so only rich people could “glass” windows with it. The peasants, on the other hand, cut holes in the walls of their houses, covered them with a bull's bladder, rawhide, canvas or paper. And only along the banks of the Angara and Lena, i.e. in those places where mica deposits came to the surface, the poor people had the opportunity to use it.

Mica was an important export item - it was exported to the East by "Persian merchants" and to the West by "Frankish and Greek merchants ... because this stone is only available here." Russian mica was considered the best in the world and was known in Europe under the name "muscovite".

But in terms of strength and ability to transmit light, mica cannot compete with glass, so in the 18th century they began to replace mica windows with glass. At first it affected the houses of rich people, and then glass windows became everywhere, although for a long time glass and mica still coexisted, and in some regions of Russia mica windows remained until the beginning of the 20th century.

Time and humidity - the main enemies of mica - mercilessly delaminate the once dense plates and turn them into a brilliant placer. Now only a few copies of mica windows and ancient mica products can be seen at expositions and exhibitions. Most of of these unique treasures is hidden in museum vaults. Collections of ancient mica windows are in the museums of the Moscow Kremlin, the State Hermitage, the State historical museum, the Kolomenskoye Museum-Reserve and the Pereslavl-Zalessky Museum-Reserve.

Here is such an interesting mineral - mica.

The chemical composition of mica reaches 40 elements. At the same time, sharp fluctuations in the chemical composition are observed even in micas of the same deposit and, often, of the same crystal.

In the middle of the 17th century, the price of sheet mica varied from 20 to 50 kopecks per sheet. For comparison, foreign merchants of that time paid 16 rubles for 1000 squirrels, 1 ruble for a pood of black caviar.

In Russia at the beginning of the 21st century, a paradoxical situation has developed: a state with huge mica resources is forced to buy it abroad, since its own production is practically not carried out. History is cyclical: an absolutely identical situation was observed at the beginning of the last century.

In accordance with the spectral classification of asteroids, a rather rare type of G-class carbon asteroids is distinguished. It is believed that these asteroids are mainly composed of low-temperature hydrated silicates, such as mica and clay with an admixture of carbon or organic compounds.

The name of the mica variety "vermiculite" comes from the Latin word "worm", because when heated, it forms long worm-like columns and bundles.

Mica plates are also widely used as a material for design. Thus, mica is used for fireplace screens, creating a decorative effect and at the same time protecting against high temperatures.

The second half of the 18th century was marked by success in the production of glass and a decrease in its price. This led to a drop in demand for mica, a reduction in its production. However, the portholes of warships continued to be made of mica, because the glass ones could not withstand the volleys of guns.

Mica, having high dielectric properties, significant heat resistance, and the ability to split into the thinnest sheets, is an unsurpassed electrical insulating material widely used in radio engineering.

One of the largest muscovite crystals in history was found in Canada. Its size was 1.95x2.85x0.6 m and it weighed about 7 tons.

The word "mica" ("sluda") is originally Russian. The meaning of the expression "serve" from ancient times meant - "exfoliate". For the first time the word "sluda" is mentioned in the "Ostromir Gospel" (1057)

The output of finished products from sheet mica from the extracted raw materials is on average 8.25%. This causes a rather high price for products and their shortage.

In the ancient Indian city of Teotihuacan in Mexico, a strange structure called the "Mica Temple" was discovered. Similar structures have not been found anywhere else in the world. Its uniqueness lies in the fact that the structure is covered from above with a double layer of mica-muscovite, the purpose of which is still unknown.

Mica is one of the most common minerals in the earth's crust. In ordinary rocks, it occurs in the form of tiny scales. Industrial deposits, where crystals reach large sizes, are extremely rare.

Muscovite mica is transparent and has a glassy sheen. Phlogopite, as a rule, is a dark mica, translucent only in thin sheets.

August 1689 is considered to be the starting point of the mica industry in the Mamsko-Chui region, when the Yakut voivode Zinoviev issued the Cossack Afanasy Pushchin the "Punishment Memory", with which he undertook to "... find and fish along the Vitim river of mica ..."

Thermal resistance of muscovite, i.e. the temperature at which it retains its properties, reaches 700 degrees Celsius. For comparison, the melting point of aluminum is 660 degrees, lead - 327, silver - 962.

Neither the ancient Greeks nor the Romans were familiar with mica. In scholarly treatises Western Europe began to call mica "Vitrum Moskovitikum", i.e. glass of Muscovy. Later, the name was simplified, became shorter - "Muscovite" and, finally, strengthened in mineralogy as "Muscovite"

During the time of Peter I, there was a great demand for mica ("Moscow glass") from Western Europe and America, used for portholes of warships, which was satisfied mainly at the expense of Mamskaya mica.

Muscovite mica has a high chemical resistance. Hydrochloric acid does not decompose it when heated to 300 degrees Celsius. It is also not susceptible to alkalis.

Mica refers to electrical insulating materials upper class heat resistance: when heated to several hundred degrees, it retains its electrical properties.

If mica is added to concrete, this will dramatically increase its strength, while heat and sound conductivity will decrease.

For the first time, synthetic mica, fluorophlogopite, was obtained by the Russian scientist K.D. Khrushchev in 1887. Artificial mica is almost transparent and surpasses natural mica in a number of characteristics.

During the years of the Great Patriotic War the need for high quality mica used in the defense industry has increased dramatically. Mica was in an acute shortage: the Karelian deposits were captured by the enemy, the Biryusinskoye was depleted. The entire extraction of muscovite was carried out only at the Mamsko-Chuyskoye deposit.

Neither the ancient Greeks nor the Romans were familiar with mica. In the scientific treatises of Western Europe, they began to call mica "Vitrum Moskovitikum", that is, the glass of Muscovy. Later, the name was simplified, became shorter - "Muscovite" and, finally, strengthened in mineralogy as "Muscovite"

The output of finished products from sheet mica from the extracted raw materials is on average 8.25%. This causes a rather high price for products and their shortage.

If mica is added to concrete, this will dramatically increase its strength, while heat and sound conductivity will decrease.

Mica belongs to the electrical insulating materials of the highest class of heat resistance: when heated to several hundred degrees, it retains its electrical properties.

During the Great Patriotic War, the need for high-quality mica used in the defense industry increased dramatically. Mica was in an acute shortage: the Karelian deposits were captured by the enemy, the Biryusinskoye was depleted. The entire extraction of muscovite was carried out only at the Mamsko-Chuyskoye deposit.

Mica is one of the most common minerals in the earth's crust. In ordinary rocks, it occurs in the form of tiny scales. Industrial deposits, where crystals reach large sizes, are extremely rare.

The name of the mica variety "vermiculite" comes from the Latin word "worm", because when heated, it forms long worm-like columns and bundles.

Mica plates are also widely used as a material for design. Thus, mica is used for fireplace screens, creating a decorative effect and at the same time protecting against high temperatures.

Muscovite mica is transparent and has a glassy sheen. Phlogopite, as a rule, is a dark mica, translucent only in thin sheets.

One of the largest muscovite crystals in history was found in Canada. Its size was 1.95x2.85x0.6 m and it weighed about 7 tons.

Muscovite mica has a high chemical resistance. Hydrochloric acid does not decompose it when heated to 300 degrees Celsius. It is also not susceptible to alkalis.

The chemical composition of mica reaches 40 elements. At the same time, sharp fluctuations in the chemical composition are observed even in micas of the same deposit and, often, of the same crystal.

Muscovite is a rock-forming mineral belonging to the category of dioctahedral micas. Its structure is potassium and aluminum aluminosilicate with hydroxyl. Chemical formula stone - KAl2 (OH) 2. Unlike most other natural minerals, muscovite is not a jewelry material. The main scope of its application is electronics and radio engineering. Some varieties are used to make optical glass.

Muscovite is a rock-forming mineral belonging to the category of dioctahedral micas.

Mica has been known to people since ancient times. In the Middle Ages, its main supplier in European states was Muscovy, which the Italians called "Muska". It is from this word that the name "muscovite" comes from, used to refer to mica. The British for a long time called the mineral "Muscovite glass". Later, the stone was called potassium mica, white mica, cat's silver, batchelorite, Moscow star, shernikite, antonite, etc.

The mineral muscovite is a translucent mica that ranges in color from completely transparent and white to green and brown. crystal lattice rocks form tetrahedra, forming endless rows. They are based on aluminum, silicon and water, connected to each other by potassium ions. Muscovite easily splits into thin elastic-flexible leaves.

Since it is mica, its description largely coincides with talc. In order not to confuse these types of stones, you need to pay attention to their leaves. In talc, they are devoid of elasticity, and this is its main difference from muscovite.

The physical properties of mica are manifested in a very perfect cleavage and low hardness (only 2-2.5 units on the Mohs scale). Others hallmarks minerals are:

glass mother-of-pearl luster;
elasticity;
refractive index - 1.6;
density about 3 g/cm³;
many-sided syngony;
high electrical insulating properties.

Gallery: Muscovite stone (25 photos)

Varieties of mica, places of their extraction

Muscovite stone has several varieties that differ from each other in chemical composition and properties.

Sericite is a dense, finely flake white mica with a high silica content and a silky sheen. Other names for the breed are episericite and lepidomorphite. Sericite is often found near gold, copper and other types of mineralization. Mineral samples intergrown with quartz are valuable raw material for the porcelain industry. Sericite is difficult to melt and does not decompose in acids. It is of hydrothermal and metamorphic origin. Occurs in beresites, quartzites, phyllites and sericite schist.

Fengite is a mineral with a high silicon content. At the same time, aluminum in its structure is often replaced by magnesium or iron. Fengite with a large amount of chromium is called mariposite. Stones with manganese in the composition are called alurgites.

Mica has been known to people since ancient times. In the Middle Ages, Muscovy was its main supplier to European states.

Fuchsite is a layered silicate containing chromium oxide. These stones are characterized by high elasticity and refractoriness. Fuchsite has a rich emerald green color. Mining of the mineral is carried out mainly in chromium deposits.

Gumbelite is a magnesian hydromuscovite with a fibrous structure. Previously, it was considered a variety of pyrophyllite, but today it has been finally proven that it belongs to micas. The mineral is different in gray. It is mined in the carbonaceous shales of Karelia.

Damurite - partially hydrotized fine-flake or dense sericite white color, constituting the parent rock of staurolite or disthene.

Roscoelite is a very rare, finely flaky variety of muscovite that is olive green, brown, or black in color with a pearly sheen.

Gilbertite (gilbertite) is a small-scale or cryptocrystalline form of green mica. Found in ore and pegmatite veins.

Mica is a mineral mined in many countries, but its main supplier, as in ancient times, is Russia. The largest stone deposits in our country are located in Eastern Siberia and on the Kola Peninsula. Muscovite is mined abroad in Brazil, Canada, the USA, India and Madagascar. Insignificant deposits of the mineral sericite are found in Kazakhstan, Turkey, Germany, Switzerland, Peru, Japan, Australia, Greenland and Antarctica.

Edged mica muscovite (video)

The use of muscovite in industrial production

Muscovite is an excellent dielectric widely used as a DC insulator. Large-crystalline varieties of stone are used in the production of radio and electrical goods. The mineral is used in the creation of modern power plants. Electrical insulating gaskets from it are used in the manufacture of electrical appliances. Sheet muscovite is used as a raw material for the production of capacitors and telephones.

Muscovite is an excellent dielectric widely used as a DC insulator.

Powder is made from mica, which is subsequently used to make building materials, heat-resistant paints, car tires and glass, mica cardboard, wallpaper, writing paper. Mica-muscovite is part of the grindstones and lubricants. In the metallurgical industry, windows for blast furnaces are made from the mineral.

The application of mica is necessary condition to create mycalex, a heat-resistant material obtained from a mixture of muscovite and fusible glass. Its use allows you to create boards, combs of inductors, holders of powerful lamps and other parts used in modern electrical and radio equipment.