Minerals
Minerals are natural bodies that are homogeneous in chemical composition and physical properties. They were formed as a result of physicochemical processes that occur on the surface of the Earth and in its bowels. Minerals are components of rocks. Most minerals are solid, having a crystalline structure, capable of forming polyhedrons (crystals). In addition to solid, there are liquid minerals (mercury, water), gas (methane, carbon dioxide).
Part of the minerals is formed as a result of magmatic activity as products of crystallization of magma, as well as due to chemicals released from it.
Minerals also arise as a result of exogenous processes. This occurs during chemical weathering when unstable substances turn into other, more stable.
To determine the minerals, it is first necessary to find out their physical properties. It should be remembered that, depending on the impurities, these properties may vary.
Physical properties include:
luster: the ability to refract and reflect light rays;
cleavage: the ability to split along certain planes, which depends on the structure and crystal structure;
hardness: ability to withstand pressure or cutting. There is a 10-point scale of mineral hardness: talc - 1; diamond - 10. Hardness is determined by comparing the studied minerals with the minerals of this scale. In addition to physical properties, their chemical properties are also examined to determine minerals.
By chemical composition, all minerals are divided into several groups.
Native elements. Found in nature is relatively rare. These include gold, silver, platinum, copper, diamond, graphite, sulfur.
Sulfides. This group includes about 250 minerals. Many of them are of great industrial importance: lead ore, zinc ore, copper ore, mercury ores.
Halogens. This group includes salts such as stone and potassium. They are used to obtain fertilizers that are used in agriculture.
Oxides. This group includes minerals, which are compounds of chemical elements with oxygen. Of these, quartz (silicon oxide) should be noted - one of the most common minerals in the earth's crust; corundum (hardness - 9), which is also found in nature in the form of red crystals - rubies, blue - sapphires; hematite (red iron ore) and magnetite (magnetic iron ore) - iron ores, as well as brown iron ore (limonite).
Carbonates. This group includes calcium compounds: calcite, used in optics; marble used as building material; malachite - a valuable ornamental stone; iron spar - ore for iron;
Ozurite - ore to copper. Sulphates. Among them, the most important is gypsum. Phosphates In this group, apatite is of the greatest importance.
Silicates. These include silicon compounds. They make up 75% of the mass of the earth's crust. Among them there are rock-forming minerals: mica, augite, hornblende. Many silicates are of great economic importance: kaolinite and talc - raw materials for porcelain and faience; olivine (chrysolite) is a gem. Feldspars are widespread, they form a whole group of minerals. They are contained in the earth's crust 57.9%.
Organogenic. This is a special group of minerals that differ in the peculiarity of their formation. This group includes ozokerite (mountain wax), asphalt - a product of oil oxidation; amber is a petrified resin of ancient conifers. It is used as an ornamental stone to obtain succinic acid, varnish, varnish, and other products. There are about 3000 different minerals. But only a few dozen minerals are found in nature in large accumulations - for example, quartz, feldspar, calcite. Most of the minerals are very rare and do not form rocks - for example, gold, diamonds.
Studying the composition of minerals and the conditions of their formation in nature made it possible to artificially produce some of them in laboratories and factories. So, for example, the production of synthetic diamonds, rubies and other minerals has been mastered mainly for technical needs.
The minerals used in the national economy are called mineral resources. Groundwater in some areas of the planet contains an increased amount of dissolved substances and gases. Such sources are called mineral. They can be used for medicinal purposes. Minerals can be used directly as they are found in nature (marble, mica, rock salt), or certain chemical elements are extracted from them (for example, iron from ore).