Among basalt rocks in terms of mineral and chemical features distinguish three series.

1. Tholeiite series (pijonitic basalts). They have the following features:

a) increased content of SiO 2 up to 50 wt. %;

b) the presence of pigeonite (a variety of diopside-augite with a low content of CaO);

c) the groundmass contains either quartz-feldspar micrographic intergrowths or glass of acidic composition;

d) olivine is often present in phenocrysts, though in smaller amounts than in olivine basalts;

Basaltic magma of this type, if it does not come to the surface, differentiates as follows: basalt → andesite → rhyolite.

2. Olivine basalts of the alkaline series (hypersthene basalts). The features of these basalts are as follows:

a) undersaturation of SiO 2 (about 45 wt.%);

b) olivine phenocrysts make up to 40%;

c) feldspathoids 11 , alkali feldspar 12 , zeolites may be present in the groundmass;

Basaltic magma of this type during differentiation processes at depth gives the following series of rocks: basalt → alkaline trachyte → phonolite.

3. Basalts of the calc-alkaline series (aluminous basalts). The features of these basalts are as follows:

a) a high content of Al 2 O 3 (> 16.5 wt.%), while in the remaining series, the content of alumina varies from 8 to 16 wt.%. %;

V) mineral composition also intermediate between series 1 and 2. The groundmass can contain both quartz and nepheline, depending on which series they are closer to.

Basaltic magma of this type, if it does not come to the surface, differentiates as follows: basalt → trachyandesite → trachyte.

Textures and structures of basalts

The most common textures of basalts are fluid, bubbly, and amygdaloidal. The structure of basalts is generally porphyritic or aphyric.

The structures of the bulk are divided into two groups.

1. Full crystalline:

a) diabase (an analogue of the ophitic structure in gabbro is a sharp idiomorphism of plagioclase microlites relative to a colored xenomorphic mineral) (see Fig. 12, b);

b) dolerite (idiomorphism of plagioclase in relation to mafic minerals, which form accumulations of small grains between plagioclase microlites; grains of mafic minerals are isometric).

2. Semi-crystalline structures are classified according to the quantitative ratio of microlites and volcanic glass:

a) intersertal (microliths 75%, volcanic glass 25%) (see Fig. 14, A);

b) hyalopilitic (ratio of glass and microlites 1:1);

c) vitrophyric (25% microlites and 75% glass).

Full-crystalline (intersertal) structures are the most common, since the process of solidification of basalt magmas lasts quite a long time.

Altered basalts (metabasalts)

Volcanic rocks from the time of their formation are subject to change, there is a so-called process of "aging" of rocks. IN general case it is of two types.

1. Greenstone regeneration - typical for volcanic rocks of mobile geosynclinal-folded zones. During this process, the main plagioclase is replaced by a Saussurite aggregate (epidote + albite, chlorite, etc.) or pure albite and epidote. Colored silicates are replaced by: olivine - serpentine, talc, iddingsite; clinopyroxene - actinolite, chlorite; rhombic pyroxene - serpentine, chlorite. The glass is replaced by chlorite and epidote group 13 minerals. As a result of such alterations, the metabasalts consist of albite, minerals of the epidote group, chlorite, actinolite, and leucoxene 14 . The rocks acquire a greenish color. The porphyritic texture is usually preserved, but the structure of the groundmass is usually difficult to recognize. Therefore, when characterizing the structures of altered basalts, the word "relict" is added. The rocks are called metadolerites or metabasalts.

2. Red stone regeneration is characteristic of calm tectonic environments of platforms, and is also characteristic of island volcanism. Among the secondary minerals, calcite is widely developed; it replaces both plagioclase and nonferrous minerals. Due to the development of minerals of the epidote and chlorite group, which have a green color, and dispersed red hematite, the rock acquires a burgundy-violet color.

Among the lava flows of the basic composition that form under underwater conditions, along with lavas of a massive structure, so-called pillow lavas, or spherical (cushion) lavas, are often encountered. Metamorphically altered lavas are called spilites. They are characterized by a sharp predominance of Na over K and a spilite structure. They compose independent bodies or are located in the upper part of lava flows (above massive lavas).

Visually, basalts are difficult to distinguish from effusives of intermediate composition. In their macroscopic determination, one has to be guided by the general color and material composition of the phenocrysts, as well as the chemical composition.

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 cainotype , 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

Average chemical composition 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 coefficient 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 relatively low temperature melting 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 the raw material 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 basalt deposits with industrial reserves of 6.5 million m³ have been explored 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 is the main effusive rock of the normal series, as well as the most common of all cainotype rocks. Basalt can be easily recognized by appearance. Its color can be black, dark gray, when weathered, these stones become brown or green. Basalt has a mineral composition. The most common accessory mineral is apatite.

The name of this stone comes from the Ethiopian word "basal", which can be translated as "boiled". This name was given to this stone because it is formed in hot volcanic vents, the temperature there can reach several thousand degrees.

Basalt stone is characterized by increased hardness, has a high density. The composition of basalt is dominated by calcium feldspar and its varieties. There are also impurities of olivine.

Initially basalts it was customary to classify them in one group along with many other similar breeds, but then they began to be distinguished separately. Basalt flows are characterized by columnar separation, while marine basalts are often pillow-shaped. Many basalts are entirely composed of mineral grains so small that they can only be diagnosed under a microscope. Basalts usually have a dense, porous structure; crystals cannot be seen without a microscope.

Sometimes the old Swedish name "trapp" is still used for basalts.

Basalt deposits

They are the most common igneous rocks on the surface of the Earth and other planets. Most of them are formed in the mid-ocean ridges. They form the oceanic crust. also forms extensive basaltic plateaus. These minerals are mined in open pits. Basalts are the main igneous rocks on the territory of the CIS. More than 200 deposits of basalt rocks are known, of which more than 50 deposits are exploited.

The formation of these minerals occurs during the solidification of basaltic magma, which pours out onto the earth's surface, moreover, we are also talking about the ocean floor. Basalts are very easily altered by hydrothermal processes. At the same time, they acquire a greenish or bluish color. The most intensive changes are those basalts that form at the bottom of the seas. The reason for this is their active interaction With sea ​​water, which leads to a radical change in their composition.

The main deposits of this mineral are located in India, USA, Italy. On the territory of our country, basalts are actively mined in the Kuril Islands and Kamchatka. These stones are also mined in Altai, on the territory of Ukraine, in Iceland, Ireland and Scotland. Basalts are mined in Northern and Central Asia. The Hawaiian Islands in the USA are a large basalt island.

Application of basalt

Basalts are of the greatest interest as a raw material. Currently, this stone is widely used in construction, because basalt is quite resistant to weathering. It can be used for exterior decoration of buildings. It is also often used to make sculptures that are intended to be installed outdoors.

Basalt is chemically resistant and high strength. However, the use of basalts as a natural stone material is limited. These minerals, although they are hard, but they are easily split and well polished. The technical qualities of basalts differ depending on the place where they are mined, and they may differ even within the same deposit.

Not all basalts are equally suitable for use in construction. It depends on the degree of their granularity, the nature of the individual pieces and the degree of weathering. The finest and medium-grained varieties of basalt are considered the best in this regard. But coarse-grained varieties are not so good, because. they are more easily weathered.

Basalt chips and dust are used for the production of anti-corrosion coatings. Such coatings are highly resistant to alkalis, acids and other media. They are thermally insulating, fire resistant and soundproof.

The disadvantages of this mineral include its low degree of refractoriness. In addition, pavements paved with basalt become too smooth over time. However, the low refractoriness of basalt makes it indispensable for use in such industries as stone casting. melted with subsequent spraying, which makes it possible to obtain basalt fiber from it. This fiber is an excellent heat and sound insulating material. To melt basalt, it must first be finely crushed to form basalt chips.

Basalt Construction Materials have good performance characteristics, due to which they are widely used in construction. Basalt is able to withstand temperatures over 1500 degrees Celsius. Therefore, it is often used as fire protection. It is resistant to alkalis and acids, as well as abrasion. Basalt is strong and durable, it absorbs noise and has thermal insulation properties. Another important quality of such material is its environmental friendliness, which is also very important in construction.

Widely used on outdoors. It is used in the cladding of buildings, the design of bridges, fountains, underpasses and facades. At the same time, basalt is quite inexpensive, which contributes to its popularity. Basalt pillars are used in port facilities. Basalt is used in the form of crushed stone and paving stones in road construction. Basalt is also used as an aggregate for concrete. Basalt is one of the most durable building stones. People have been using it in construction since ancient times. So, numerous architectural monuments are made from it. Red Square in Moscow is paved basalt.

Healing properties of basalt

According to modern lithotherapists, basalts have some healing properties. It is generally accepted that this mineral combines all four elements. And these stones are especially well suited for use in stone therapy. This method of treatment has been known since ancient times in the East. And in our country they began to practice it relatively recently, but this species therapy is now quite popular with us and is offered by many massage parlors. Stone therapy not only helps to relax well, it also helps to strengthen the body's immune system. This technique is based on the use of stones, the main of which is basalt. It is best to use dark gray and black rocks for this procedure. It is recommended to use basalts that contain olein.

Basalt has the ability to retain heat for a long time. Therefore, in thermal terms, it has the maximum effect on the human body.

The magical properties of basalt

magical properties basalt is still insufficiently explored. Therefore, there is no single practice of their application in this area. It is believed that this mineral has the male Yang energy, so it is most often used not as an independent mineral, but in combination with other stones.

The word "basalt" is of Ethiopian origin. It was formed from the word "basal", which literally means "boiled". It is this name that the stone received because it is formed in the red-hot vents of volcanoes, in which temperatures reach several thousand degrees.

The stone is easily recognizable by its appearance. It has dark, black, grey-black, ashy coloration. The mineral is very hard, has a high density. Basalt is composed of calcium feldspar and its varieties. There are also impurities of olivine.

Basically, basalt occurs in nature in the form of interstratal bodies or in the form of lava flows that appear as a result of an eruption through the main volcanic vent or through volcano fissures. In theory, two types of basalts are distinguished: those that contain olivine and those that do not contain it (tholeiitic basalts).

The latter often also contain elements of quartz. Basalts with olivine are most often found on islands, especially on those located in the volcanic belt of the Pacific Ocean. Tholein rocks create the so-called tramp formations of the continents.

Huge deposits of basalt were found in the form of lava flows in India (in its western part, on the Deccan Plateau), in the USA (Washington, Oregon and Idaho on the Columbian Plateau, on the Hawaiian Islands). The rocks near the volcanoes Etna and Vesuvius in Italy are also rich in this mineral. In the territory former USSR the mineral has been actively mined and is being mined from lava flows of volcanoes on the Kuril Islands and Kamchatka. Also, basalts can be found on the territory of Ukraine and Altai, but these deposits are underdeveloped. On the territory of Europe, the most famous basalts are mined in Iceland, Scotland and Ireland.

Healing properties of basalt

On this moment The healing properties of basalt are mainly used in stone therapy. This method of treatment has been known since ancient times, we have begun to practice it relatively recently, having adopted the experience of our Eastern colleagues.

Stone therapy can enhance immune system organism. Founded this technique on the use of stones, the main of which is basalt. Doctors recommend using dark gray and black breeds for this procedure. It is best to use basalts containing olein.

It is believed that basalt combines all four elements: fire, earth, air and water. The stone keeps heat in itself for a long time, so its effect on the body is maximum in thermal terms.

The magical properties of basalt

The magical properties of basalt have not yet been sufficiently studied, therefore, a uniform practice of its use has not yet been developed. It is believed that basalt carries male energy, Yang energy. Therefore, it is usually used in combination with other minerals.

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BASALT - STONE

Basalt (Latin basaltes, basanites, from Greek basanos - touchstone; according to another version, from Ethiopian basal - iron-bearing stone) are the most common igneous rocks on the surface of the Earth and on other planets. The main mass of basalts is formed in the mid-ocean ridges and forms the oceanic crust.

The entire globe is completely covered with a thin shell of basalt (only about 10-20 km thick). No one really knows what's under the shell. In some places, granite blotches are slapped onto this basalt shell - these are continents. All bottoms of the oceans are the surface of a basalt shell! This is how it works Earth. Texture of basalt - mostly dense, porous, crystals are not visible to the naked eye, characteristic colors basalt stones- in grey-black scale; shades: sometimes greenish, sometimes reddish brown.