The main rock-forming minerals

Pore-forming minerals are the minerals that form part of rocks as their permanent essential components. They differ from each other in their physical properties and chemical composition. In addition to rock-forming minerals, there are also secondary. They are found in the form of impurities and do not play such a large geological role.

Plagioclase

Plagioclases are the most common rock-forming minerals. They are a mixture of anorthite and albite. There are many varieties of plagioclase. When the share of anorthite increases, the basicity of the mineral rises.

Plagioclases differ in their instability with respect to chemical weathering, because of which they become clay compounds. In this particular feature they are similar to feldspars. They can be used as facing and decorative material. Almost every rock-forming mineral of the plagioclase group occurs in the Urals or in Ukraine.

Nepheline

Nepheline belongs to the group of skeletal aluminosilicates. It is depleted in silica. Similar rock-forming minerals are included in igneous rocks, including nephelinites and nepheline syenites. Easily eroded from the earth's surface and transformed into kaolinite, as well as secondary formations of sulfate or carbonate composition.

Together with apatites, nepheline rocks can form vast arrays, very important for modern industry. They are used in the production of glass, cement, alumina, silica gel, soda, ultramarine, etc. These basic rock-forming minerals are found on the Kola Peninsula in the Murmansk region.

Amphiboles and pyroxenes

Amphiboles, or band silicates, include hornblende, which is an important rock-forming component in metamorphic and magmatic rocks. Its distinctive features are high strength and high viscosity. Most common hornblende is found in the Urals.

Augite is a rock-forming mineral of pyroxenes. It is an important component of igneous rocks. The color of augite can be very different (from black to green). This rock-forming mineral from the group of pyroxenes is a part of basalt, andesite, diabase and some other rocks.

Mica

Some silicates have a lamellar, scaly or leafy structure. The most common such minerals are asbestos, talc, kaolinite, hydromica, and mica (including muscovite and biotite).

What are their other features? Muscovite is a white mica, found in metamorphic and magmatic rocks. When weathering, it becomes loose. Muscovite is used as an electrical insulating material. It is also used in construction, where mica powder is a common padding material. Muscovite is mined in Eastern Siberia, the Urals and Ukraine.

Similar rock-forming minerals are biotites. It is a magnesian and glandular mica of brown or black color. It is characteristic of metamorphic and igneous rocks. Biotite forms granular and scaly clusters. It is considered to be a mineral of a chemically unstable character. Biotite is found in Transbaikalia and in the Urals.

Hydromica

Another rock-forming mineral of rocks is hydromica. Their characteristic feature is a small number of cations. In addition, hydromica differs from mica by a markedly higher content of water in its composition, which is reflected in their name. Their formation is promoted by hydrothermal processes and weathering of rocks.

The most valuable hydromica is brown or golden vermiculite. When heated, the molecular water of this mineral forms vapor expanding the interlayers in the crystal lattices, which increases its volume and density. Vermiculite is valuable due to its sound-absorbing and heat-insulating qualities.

Layered silicates

Minerals asbestos, talc, montmorillonite and kaolinite belong to the group of layered silicates. What is their feature? The formation of talc occurs as a result of the interaction of hot solutions with aluminosilicates and magnesian silicates. It is applied in the form of a powder in the manufacture of plastic.

Like some other rock-forming minerals, asbestos is known as several of its varieties. It poorly conducts electricity and heat, differs alkalinity and fire resistance. The highest value is possessed by chrysotile asbestos. It is formed from carbonate and olivine rocks. In the long-fiber form, asbestos is used in the manufacture of certain automotive parts and non-combustible fabrics.

Kaolinite is considered to be the most frequent mineral of clay rocks. It is formed as a result of weathering of micas and feldspars and is characterized by high stability. This mineral is white, grayish or brownish in color. Kaolin clays are used in the ceramic industry, where this raw material is used in the manufacture of faience and porcelain ceramics. Due to the properties of its forming mineral, these materials are characterized by ductility.

Montmorillonite is unusual in many respects. Its chemical composition is unstable and depends on the properties of the atmosphere, including the content of water in it. These main rock-forming minerals have a mobile crystal lattice, which is why they swell strongly when they come in contact with moisture.

Montmorillonite is formed in an alkaline environment due to the decomposition of tuffs and volcanic ash in water. It also appears in the places of weathering of igneous rocks and is stable with respect to chemical weathering. This mineral imparts additional adsorption and swelling to clayey rocks. Montmorillonite is used as an emulsifier, filler and bleach. Its deposits are in the Crimea, Transcarpathia and the Caucasus.

Quartz

Mineral oxides are compounds of metals and oxygen. The most common representative of this group is quartz. This mineral is formed as a result of magmatic processes occurring in deep earth's interior. It occurs in three variations: cristobalite, tridymite and a-quartz. The last of these modifications has been studied better than the others.

Quartz is part of the rock-forming minerals of magmatic rocks (as well as sedimentary and metamorphic minerals). It is chemically stable. Quartz accumulates, forming powerful sedimentary deposits, sands and sandstones. Mineral is used in the ceramic and glass industries. As a natural stone (sandstone and quartzite), it is popular as a structural and facing building material. It is also used in the manufacture of chemical dishes, optical instruments, etc.

Carbonates

Another group of rock-forming minerals is carbonates. They are widely distributed salts of carbonic acid. Carbonates are characteristic of metamorphic and sedimentary rocks. The most common types are magnesite, calcite and sodium. They all have their own individual properties.

Calcite is characterized by poor solubility in water. When exposed to carbon dioxide, it can pass into bicarbonate. This product will dissolve in water a hundred times faster than ordinary calcite. This mineral is found in crystalline aggregates, deposits and powerful deposits of marble and limestone. Calcite can form as a result of sludge accumulation. Another cause of its occurrence is the deposition of carbonic acid lime in water. Deposits are found in the Urals, Ukraine and in Kaleria.

Magnesite is similar to calcite in form and structure, but it is much less common in nature. The reason in the factors of its formation. Magnesite is formed as a result of the weathering of serpentinites, as well as the interaction of magnesian solutions and limestones.

Nitrite is a white or colorless mineral, occurring in the form of granular and dense masses. When heated, it dissolves. Nitrite is formed in sodium salt lakes in the case of excess dissolved carbon dioxide in them. This mineral is used in metallurgy and in the manufacture of glass.

Opal

Opal is a widespread amorphous hydrated silica. It does not decompose in acids, but is soluble in alkalis. There are several conditions for its formation. This mineral appears due to precipitation from geysers and hot solutions, as well as weathering of igneous rocks. In addition, it is formed due to the accumulation of the products of vital activity of organisms inhabiting the sea. Opals are a popular material for jewelers.

Sulphates and sulphides

Minerals sulfates are salts of sulfuric acid, formed on the earth's surface. Most of the compounds of this group are not sufficiently stable in the crust of the planet. Such sulfates, such as gypsum, mirabilite and barite, are used for construction purposes. Anhydrite is a continuous granular mass. It is a crystalline mineral with a characteristic whitish-blue color.

When it comes into contact with water, anhydrite increases the volume and becomes a gypsum that forms an impressive accumulation of rocks. This sulfate is a typical chemical precipitate formed when the seas dry out. Gypsum and anhydrite are used as binders.

Heavy spar or barite is a crystal with a specific tabular form. It misses X-rays badly, which is why it is used in the production of special concrete. Barite is formed as a result of precipitation from aqueous hot solutions.

Sulphides are sulfur compounds with other elements. This class includes cinnabar. This mineral is associated with young volcanoes. In nature cinnabar occurs in the form of veins and reservoir deposits. It accumulates in the form of placers due to its own stability on the earth's surface. Cinnabar is used in the synthesis of mercury and the manufacture of paints.