Basalt is a very popular stone, which is found everywhere not only in the CIS countries, but also abroad. Regardless, most people don't know what basalt is. This article will provide an answer to this question.

Basalt is an igneous rock. Has the main composition. The name comes from the Ethiopian "basal" - boiled, which means "a stone containing iron." In nature, it can be found in the form of stones of various shapes or in the form of a lava flow.

Most often it has a dark gray, black or greenish-black color. It is in green that basalt is most often found in the photo. The structure is also different. glassy, ​​cryptocrystalline aphyric and porphyritic. In the case of a porphyritic structure, one can notice inclusions of crystals of greenish-yellow olivine, light-colored plagioclase, or pyroxenes that have the shape of black prisms. Inclusions make up from 15% to 30% of the mass of igneous rock. The size of the phenocrysts is several centimeters in length.

Stones can have a dense, massive, almond-like and porous texture. Tonsils can be filled with calcite, chlorite, plagioclase and other minerals. Stones with tonsils are called mandelsteins.

The stone stands out for its unique properties. Among the stones, it is considered the most elastic and plastic. It stretches well, which allows it to be used in the manufacture of things of small sizes.

The melting point of the stone fluctuates 100 to 1500 degrees Celsius. This melting point allows it to withstand extreme temperature fluctuations.

Considering its strength, resistance to shock and temperature changes, one can understand why it is so often used in the design of public spaces and on the street.

How and where is basalt formed?

The main method of stone formation is solidification of magma erupted from the lower layers of the earth. Silicate igneous melt of basalt composition is also taken into account. The origin of magma itself comes from the rocks of the Earth's mantle. The type of the resulting basalt is determined by the composition of the initial substance (rock) from which it is formed. And also this is influenced by the conditions under which it melts and the mechanism of melt escape.

Basalt is an igneous rock found on much of the Earth and other planets. Almost the entire oceanic crust of the planet Earth consists of it. Deposits of this stone are formed in the form of traps - structures that look like stairs. These traps are located on 150,000 square kilometers of the Yenisei and Lena river basins. And also the stone is mined in eastern Siberia.

In addition to the CIS countries, it is mined in America, Brazil, Greenland, Iceland and Australia. Among foreign countries, India is considered the richest in deposits of this stone.

Extraction of stone is carried out in mines and quarries. The mined basalt is sent to enterprises engaged in the manufacture of things using this stone.

Scope of stone use

The areas of application are many. This stone is very common due to the fact that it has great features:

One of the main areas of application of basalt is architectural construction. Thanks to good technical specifications It can be used for building cladding and interior decoration. The characteristics allow you to install basalt products even in open areas under the influence of external negative factors.

It can also be used in construction. For example, to create high-quality building materials and insulation. In addition, its strength is sufficient to build columns and arches out of it. In the production of reinforced structures, basalt powder is added to the product to increase its strength and reliability.

Basalt is a stone that is very popular both in construction and architecture. In addition, there are a huge number of photos of basalt in interior decoration that speak of its popularity in design art.

Basalt stone

Basalt is one of the most common natural stones. It is of volcanic origin: after a volcanic eruption, the magma cools quickly, and this is how this rock is formed. No wonder the stone was called in Ethiopia "basal" - "boiled". The Africans believed that it first boiled in a volcano, and only then poured out onto the surface of the Earth. And according to some versions, it is translated as "iron-containing stone." It is sometimes also referred to by the Swedish name "trapp".

Basalt has been used in the construction industry since ancient times. For example, Red Square in Moscow is paved with this stone. It has survived to this day, and this speaks of the durability of the natural rock.

Field

Large deposits of rock are found in India, the USA, the Kuril and Hawaiian Islands, and Kamchatka. Rock deposits are being developed in Russia, Armenia and Ukraine. There is a natural stone not only on Earth. Scientists have recorded its presence on Mars, Venus and even on the Moon.

Compound

Basalt consists of the following minerals:

• volcanic glass,
• plagioclase microliths,
• titanomagnetite,
• magnetite,
• clinopyroxene,
• there may also be hornblende and orthopyroxene.

Although the composition of basalt depends on the deposit, which means that it is not constant.

Structure

The structure of the stone is porous, glassy or cryptocrystalline aphyric, fine-grained, bubbly. He got the bubbly structure from the fact that when lava comes out of a volcano, gases with vapors also come out at the border with the vent, the cavities do not have time to tighten before the lava crystallizes.

Color

Among other rocks, basalt is easily recognizable, and primarily by its color. The color scheme of natural stone is dark, there are no light basalts - black, dark gray and green, probably closer to a black tint.

Types of basalt

Basalt is a general name and unites many different types:

- Asian - this is an inexpensive stone, it is widely used in interior design, as well as in the architectural industry. Its color can be compared with the color of "wet asphalt";

- twilight - the stone has a dark gray, even black color. I consider it one of the highest quality types among all others, as it is the most resistant to sudden changes in temperature, mechanical influences, resistant to moisture, etc .;

- Moorish - almond stone. It has green color with various inclusions. Thanks to the original color, it has found application in design solutions.

Characteristics and application

Basalt is a heavy stone, even heavier. If compared with the properties of the same granite, then basalt differs in its plasticity, flexibility and elasticity.

Another feature of this stone is resistance to high (melting point - 1000 - 1200 degrees Celsius, and some rocks melt at 1450 degrees) and low temperatures, as well as to its differences. resistant stone and chemicals: acids and alkalis.

• The density of basalt is 2530-2970 kg/m2;
• Water absorption varies from 0.25 to 10.2%;
• Poisson's ratio is 0.20-0.25;
• Specific heat capacity 0.85 J/kg K at 0°C;
• The resistance is in the range of 60-400 MPa….

The use of basalt is wide. First of all, it is interesting as a raw material. And the main scope is construction.

Sandwich panels and tiles are made from basalt. Slabs of natural stone trim fireplaces, monuments. In such cases, of course, limestone is widely used, but in those areas where there is a lot of basalt rock, it is even used to lay the foundation of a structure.

For strength, it is added to the concrete solution for pouring floors, sidewalks, paths, pavements. But there is one drawback - over time, the surface of the coating becomes smooth.

Basalt is an excellent material for making bridge pillars.

Its powder is added in the manufacture of reinforced products so that they are reliable and strong. They carve columns, arches, statues, frames for stairs.

It is easy to work with, so it is highly valued by decorators. Used in handmade ornamental decor external structures buildings.

Suitable for cladding exterior walls of buildings.

They insulate the facades of buildings. And here it has gained great popularity. Assembled in mats, it is a reliable, durable, resistant to external influences, heat-insulating and noise-absorbing material.

The rock is finely crushed to form basalt chips, melted in a shaft furnace at a temperature of about 1200 ° C (increases fire-fighting properties), then sprayed, this is how basalt fiber is produced. It produces a wonderful heat and sound insulating material - stone or basalt wool - a kind of modern insulation. If compared with silicate wool, then basalt is twice as superior in terms of thermal insulation characteristics. It also has high soundproofing performance. Basalt is used to make fibers for insulating roofs, walls, floors and other surfaces. Basalt chips and dust are used to make anti-corrosion coatings. They are highly resistant to alkalis and acids.

One of the disadvantages of basalt is its low refractoriness. But not for this stone, this property is a disadvantage. Low refractoriness can be turned into the dignity of a stone. It is used in such an industrial field as stone casting.

Basalt is an affordable material, since it has a relatively low cost compared to other natural materials.

BASALT (Latin basaltes, basanites, from Greek basanos - touchstone; according to another version, from Ethiopian basal - iron-bearing stone * English basalt, basaltic rocks; German Basalt; French basalte; Spanish basalto) - erupted Cenotype , the effusive analogue of . The color of basalt is dark to black. It consists mainly of the main, monoclinic, and accessory minerals -, etc. The structures of basalt are intersertal, aphyric, less often hyalopilitic, textures are massive or porous, amygdalolithic. Depending on the grain size, they distinguish: the most coarse-grained -, fine-grained - anamesite, fine-grained - basalt proper. Paleotype analogues of basalt -.

The chemical composition of basalt

The average chemical composition of basalt according to P. Daly (%): SiO 2 - 49.06; TiO 2 - 1.36; Al 2 O 3 - 15.70; Fe 2 O 3 - 5.38; FeO - 6.37; MgO - 6.17; CaO - 8.95; Na 2 O - 3.11; K 2 O - 1.52; MnO - 0.31; P2O5 - 0.45; H 2 O - 1.62. The content of SiO 2 in basalt ranges from 44 to 53.5%. According to the chemical and mineral composition, olivine unsaturated with silica (SiO 2 about 45%) basalts and olivine-free or slightly saturated with silica (SiO 2 about 50%) tholeiitic basalts are distinguished.

Physical properties of basalt

The physical and mechanical properties of basalt are very different, which is explained by different porosity. Basalt magmas, having low viscosity, are easily mobile and are characterized by a variety of occurrence forms (, flows, reservoir deposits). Basalt is characterized by columnar, less often spherical separation. Olivine basalts are known at the bottom of the oceans, oceanic islands (Hawaii), and are widely developed in folded belts. Tholeiitic basalts occupy vast areas in (formations of Siberia,). Ore deposits are associated with rocks of the trap formation, (Siberia). A deposit is known in amygdaloidal basaltic porphyrites of the Upper Lake region.

Density of basalt

Basalt 2520-2970 kg/m³. Porosity ratio 0.6-19%, water absorption 0.15-10.2%, compressive strength 60-400 MPa, abrasion 1-20 kg/m², melting point 1100-1250°C, sometimes up to 1450°C, specific heat capacity 0.84 J/kg.K at 0°C, Young's modulus (6.2-11.3).10 4 MPa, shear modulus (2.75-3.46).10 4 MPa, Poisson's ratio 0.20 -0.25. The high strength of basalt and the relatively low melting point led to its use as a building stone and raw material for stone casting and mineral wool.

Application of basalt

The use of basalt - basalt is widely used to obtain road (side and paving stones) and facing stones, acid-resistant and alkali-resistant material. Industry requirements for the quality of basalt as a raw material for crushed stone are the same as for other igneous rocks. For the production of mineral wool, basalt is usually used in blending. It has been established that the melting temperature of raw materials should not exceed 1500°C, and the chemical composition of the melt is regulated by the following limits (%): SiO 2 - 34-45, Al 2 O 3 - 12-18, FeO up to 10, CaO - 22-30, MgO - 8-14, MnO - 1-3. Basalt stone casting materials have great chemical and abrasion resistance, high dielectricity, and are used in the form of floor and cladding slabs, pipeline linings, cyclones, and various insulators.

B 50 have been explored for crushed stone with industrial reserves of 40 million m³. Two deposits of basalt with industrial reserves of 6.5 million m³ have been explored for facing stone ( , ). The annual production of basalt is over 3 million m³. In the CCCP, basalt deposits are concentrated mainly in Armenia, Eastern Siberia and the Far East. Basalt covers in the eastern regions of the United States form large deposits in the states of New York, New Jersey, Pennsylvania, Connecticut (the largest and stone crushing plants).

Basalt- the main effusive rock of the normal series, the most common of all cainotype rocks. The main minerals of phenocrysts are clinopyroxene and calcium plagioclase (N 30-90), sometimes olivine, orthopyroxene; the groundmass is composed of the same minerals (without olivine) and magnetite in glass (or without it).

Name history

This mineral became basalt from the Latin basaltes, basanites, from the Greek. basanos - touchstone; according to another version, they became basalts from the Ethiopians. basal is an iron-bearing stone.

Classifications

Varieties can be distinguished according to the features of the mineral composition (apatite, graphite, diallag, magnetite, etc.), the composition of minerals (anorthite, labradorite, etc.), the features of the structure and (or) texture, chemical composition (ferruginous, ferrobasalts, calcareous, alkaline - calcareous, etc.).

Petrochemical classification

Yoder and Tilley (Yoder and Tilley, 1962) suggested using the nepheline-olivine-diopside-quartz tetrahedron for classification. The activity of silica in the melt is controlled mainly by reactions of the type:
2(Mg,Fe)SiO3 -> (Mg,Fe)2SiO4 + SiO2 (orthopyroxene = olivine + silica)
NaAlSi3O8 -> NaAlSiO4 + SiO2 (albite = nepheline + silica)

These reactions can be divided into 3 groups:

• quartz-normative (containing excess silica)
• nepheline-normative (lack of silica)
• hypersthene-normative (in the absence of normative quartz or nepheline)

Membership in these groups is determined by chemical composition rocks, by the presence of the corresponding normative minerals in the results of petrochemical recalculation by the CIPW method.

Geodynamic classification

According to the geodynamic setting, the main types are distinguished:

• Mid-ocean ridges MOR or MORB
• Active continental margins and island arcs (IAB)
• Intraplate, which can be subdivided into continental and oceanic (OIB).

Composition and structure

They are usually dark gray, black or greenish-black rocks with a glassy, ​​cryptocrystalline aphyric or porphyritic structure. Small phenocrysts of greenish-yellow isometric olivine crystals, light-colored plagioclase, or black pyroxene prisms are clearly visible in porphyritic varieties against the background of a common cryptocrystalline mass. The size of phenocrysts can reach several centimeters in length and make up to 20-25% of the rock mass. The texture in basalts can be dense massive, porous, amygdaloidal. Tonsils are usually filled with quartz, chalcedony, calcite, chlorite and other secondary minerals - such basalt is called mandelstein. The ground mass is often not crystallized. Aphyric (without porphyritic phenocrysts) varieties are frequent.

Basalt flows are characterized by columnar separation. It occurs as a result of uneven cooling of the rock. Marine basalts are often cushion-like. It is formed as a result of the rapid cooling of the surface of the lava flow by water. The incoming magma lifts the formed shell, flows out from under it and forms the next pillow.

Prevalence

Basalt is the most common effusive rock on Earth, and on other planets as well. The main mass in basalt is formed in the mid-ocean ridges and forms the oceanic crust. In addition, basalts are typical of settings for active continental margins, rifting, and within-slab magmatism.

During the crystallization of basaltic magma at a depth, strongly differentiated, layered intrusions (such as Norilsk, Bushveld and many others) are usually formed. They are composed of various rocks, the sequence of crystallization of which is determined by the dynamics of magma crystallization. First, the highest-temperature minerals crystallize from the melt, and they precipitate to the bottom of the magma chamber. in this case, the melt is enriched in some components and depleted in others. With a decrease in temperature, a change in crystallizing minerals occurs.

Layered massifs contain deposits of copper-nickel ores, chromites and platinoids.

Origin

Basalts are formed during the partial melting of typical mantle rocks - lherzolites, harzburgites, wehrlites, etc. The composition of the melt is determined by the chemical and mineral composition of the protolith, the physicochemical conditions of melting, the degree of melting, and the melting mechanisms.

Analogues

• The hypabysal analog - dolerite is distinguished by a characteristic dolerite structure.
• Intrusive analogs of basalt are gabbro, gabbro-norites, norites, troctolites.
• Paleotype analogue of basalt - diabase

Changes

Basalts are very easily altered by hydrothermal processes. At the same time, plagioclase is replaced by sericite, olivine by serpentine, the groundmass is chloritized and, as a result, the rock acquires a greenish or bluish color. The basalts that pour out at the bottom of the seas change especially intensively. They actively interact with water, while many components are removed and deposited from them. This process has great importance for the geochemical balance of some elements. So most of the manganese enters the ocean in this way. Interaction with water radically changes the composition of marine basalt. This influence can be estimated and used to reconstruct the conditions of ancient oceans from basalts.

Metamorphism

During metamorphism in basalt, depending on the conditions, it turns into green shales, amphibolites and other metamorphic rocks. During the metamorphism of basalts at significant pressures, they turn into blue shales, and at high temperatures and pressures in eclogites consisting of pyrope and sodium clinopyroxene - omphacite.
Metamorphic rocks with a composition close to basalts are called metabasites.

Application of basalt

Basalt is used as a raw material for crushed stone, the production of basalt fiber (for the production of heat and sound insulating materials), stone casting and acid-resistant powder, as well as a filler for concrete. Basalt is highly resistant to weathering and is therefore often used for exterior decoration of buildings and for the manufacture of outdoor sculptures.

Rock Properties

• Rock type: Igneous rock
• Color: dark to black
• Color 2: Black gray
• Texture 2: porphyritic
• Origin of name: from Latin basaltes, basanites, from Greek. basanos - touchstone; according to another version, from the Ethiopian. basal - iron stone
• Structure: porphyritic
• Texture: almond stone

Rock Photo

Rock deposits Basalt

• Sinar
• Evenk Autonomous Okrug
• Russia
• lacustrine