Minerals What is a mineral? All aspects of human life are inseparable from minerals. For example, all kinds of materials needed to build a house, precious stones carried with you, and daily edible salt all come from minerals. What are minerals? Only substances that meet the following conditions can be called minerals: 1) Minerals are natural compounds or simple materials formed by various geological processes, such as volcanism. They can be solid (such as seasonal diamonds), liquid (such as natural mercury), gas (such as water vapor in volcanic jets) or colloid (such as opal). 2) Minerals have a certain chemical composition. For example, the composition of a diamond is elemental carbon (C), which should be silica (SiO2), but the natural mineral composition is not completely pure and often contains a small amount of impurities. 3) Minerals also have a certain crystal structure, and their atoms are arranged regularly. For example, the timely crystal arrangement is that the four corners of silicon ions are connected with an oxygen ion to form a tetrahedron, and these tetrahedrons are connected with each other at the corners to form a three-dimensional frame structure. If there is enough room for growth, all solid minerals have certain forms. For example, diamonds form octahedral shapes, and cylinders with horizontal stripes are often formed on cylinders when necessary. When there is no room for growth, their inherent forms cannot be expressed. 4) Minerals have relatively stable physical properties. For example, galena is steel gray, with bright metallic luster and opacity. Its powder (streaks) is black and soft (it can be cut with a knife), and it can be divided into three groups of smooth cleavage planes at right angles to each other (perfect cleavage), which is very heavy (specific gravity 7.4-7.6). 5) Minerals are the basic units of minerals and rocks. Minerals and ores What is an ore? Usually, the solid matter with smelting metal value mined from metal deposits is called ore, commonly known as ore. In mineral processing terminology, it is called raw ore, coarse ore or sand blasting. Ores are generally composed of useful metal minerals, that is, ore minerals and their associated gangue. Ore minerals refer to minerals from which one or several useful metal elements can be extracted in industry. Ore minerals are mostly opaque minerals with metallic luster, such as chalcopyrite and galena, which are copper and lead respectively. But some are transparent minerals. Ore minerals sometimes occur in the form of natural metals, such as natural gold and platinum, but most of them are compounds. All kinds of metals used in industry are extracted from many kinds of metal minerals. A metal element can be extracted from several different minerals. For example, copper can be extracted from chalcocite, bornite, chalcopyrite, chalcopyrite, native copper and malachite. Similarly, some minerals can also extract two or more metal elements, such as potassium-vanadium uranium ore, which can extract uranium and vanadium. In Chinese characters, the words "mineral" and "precious" are universal, but at first they reflected people's understanding of two minerals with different properties in nature: the former refers to non-metallic minerals and the latter refers to metallic minerals. In ancient China, all the raw minerals were called "mine" and "soup". People first used stones and clay, and then began to smelt metal ores. The emergence, coexistence and universality of the words "mine" and "town" reflect the development of social productive forces. The word "mine", originally written as "",symbolizes the image of a mining tool. As early as the Warring States Period (475 BC-22 BC1year), some officials in charge of mining called it "Man" and "Kuang", symbolizing the sound of mining. In the west, mining activities started late, and it was not until the Middle Ages that the scale expanded day by day, so the word "mineral" appeared later. It comes from the medieval Latin minera, which originally meant mine, ore and mine, hence the word Mine. Obviously, in the west, the concept of "mineral" is also formed on the basis of production practice. Minerals and rocks are widely distributed in the crust. For example, gold in sand, water and ice in rivers and lakes, salt in salt lakes, and feldspar and mica in granite are all minerals. Although some substances with similar composition and properties to natural minerals can be obtained under laboratory conditions, they are called "artificial minerals" or "synthetic minerals" because they are the products of artificial synthesis rather than natural geological processes. Meteorite and moonstone come from other celestial bodies, and the minerals in them are called "meteorite minerals" and "moonstone minerals" or "cosmic minerals". In this way, they can be distinguished from minerals formed on the earth. What is a rock? Rock refers to a solid aggregate with stable shape formed by various geological processes in the upper part of the earth (crust and upper mantle), which is composed of one or more minerals and natural glass. From this, we can easily see that rocks are an aggregate composed of one or several minerals. Among them, rocks composed of a mineral are called monazites, such as marble composed of calcite and quartzite composed of time. Rocks composed of several minerals are called composite rocks, such as granite composed of syenite, feldspar and mica, gabbro composed of basic plagioclase and pyroxene, etc. In addition, rocks are solid with stable shapes, and liquids without certain shapes, such as oil, gas, loose sand and mud, are not rocks. Man-made minerals can't meet the needs of industrial production, because some minerals produce less in nature. The research on man-made minerals started from 19 in the 1940s. The performance of many man-made minerals has approached or surpassed the corresponding natural minerals, and some man-made minerals can replace some natural minerals, and the cost is lower than the cost of mining natural minerals, and the quality and particle size of minerals are controllable. Therefore, the research and production of artificial minerals have developed rapidly. It has piezoelectric effect in time. Slices cut in a certain direction are widely used in electronic industry, such as radar. However, to obtain such a slice, it must be transparent, defect-free and timely crystal with a certain size (not less than 6×6×6mm). Although chronotropic crystals are widely distributed in nature, there are few chronotropic crystals that meet the requirements. Even with this crystal, it is easy to crack during mining, which affects the use value. Since 1947 cultivated artificial crystals in the laboratory, it has provided a large number of transparent and usable crystals for industrial production. At present, the chronotropic crystals used in the optical and electronic industries are all artificial chronotropic crystals. At the end of 1980s, the world's artificial production capacity was close to 2,000 tons. Diamonds are used in drilling and cutting, electronic industry and gem industry because of their greatest hardness, semiconductor characteristics and dazzling luster. Synthetic diamonds are synthesized in the laboratory from 1955, but the particle size is only about 1 carat. This kind of diamond is not transparent enough, so it is mostly used in cutting industry. However, only a few diamonds used in jewelry are synthetic, and most of them use other synthetic minerals as substitutes for diamonds. Artificial cubic zirconia, artificial rutile, artificial spinel, etc. These minerals have high refractive index and dispersion, and they can all have sparkling dispersion effect after cutting. They can Be used in jewelry industry instead of diamonds and embedded in rings, while synthetic diamonds contain impurities such as B, Be and Al, which makes their semiconductor performance better than natural diamonds. With the improvement of people's living standards, the demand for gems is increasing, but the output and distribution of gems are limited, so synthetic gems replace the corresponding natural gems. Artificial emeralds, artificial corundum, artificial metamorphic rocks and artificial turquoise are basically the same as natural gemstones, and they have all been produced and sold in the market. The research on artificial minerals has developed rapidly. At present, not only artificial minerals similar to those produced in nature have been synthesized, but also many artificial crystals not found in nature have been synthesized in the laboratory to meet the needs of industry. The chemical composition and crystal structure of minerals are the two most basic factors that determine all the properties of minerals. But it can be changed within a certain small range. According to their obvious changes, we can divide minerals into the following categories: 1) minerals with basically fixed chemical composition. The chemical composition of this kind of minerals is basically fixed, that is to say, the variation range of its composition is very small, which can generally be completely ignored. They obey the law of certain proportion and the law of multiple proportion in chemistry, and their chemical composition can be expressed by a certain chemical formula. For example, diamond C, halite NaCl, chalcopyrite CuFeO2, hematite Fe2O3, barite Ba[SO4], dolomite CaMg(CO3)2, etc. 2) Minerals with uncertain chemical composition. The chemical composition of this kind of mineral can change within a certain range, and this change is caused by the variation of the composition of the mineral itself. There are basically three situations here: one is solid solution, the other is zeolite water or interlayer water containing minerals, and the other is colloid. For example, olivine (Mg, Fe) [SiO _ 4], the elements separated by commas in the chemical formula indicate isomorphic substitution elements, and the ratio of Mg to Fe is not fixed. 3) minerals that do not meet the combination ratio. We also know that the chemical composition of all crystalline minerals obeys the laws of constant ratio and multiple ratio, and there is a certain combination ratio between the components. However, some crystals do not obey these laws, that is, they belong to the so-called non-compound ratio compounds. For example, galena Fe 1-xO always has fewer Fe atoms than O atoms. This phenomenon is caused by some defects in the crystal structure. The use of minerals can be said to be ubiquitous in our lives. In addition to the use of mineral components, on the other hand, it is to use various physical properties of minerals. Metallurgical industry using mineral components: extracting useful elements from minerals and smelting them into metals needed by various industries. The most important thing is to extract iron from magnetite and hematite; Extracting lead from galena; Extracting copper from chalcopyrite and bornite; Extracting chromium from chromite. The highest output mineral in China is wolframite, and the tungsten extracted from it ranks first in the world. Hunan, China is a world-famous stibnite producing area, from which a large amount of antimony is extracted. The bastnaesite used to extract rare earth elements from Bayanobo rare earth deposit in Inner Mongolia is also the richest in the world. Metals needed by national defense industry such as beryllium are extracted from stones, niobium and tantalum are extracted from niobite and tantalite, and sodium in atomic energy industry is extracted from crystalline sodium ore. In addition to the main elements, minerals will be mixed with some trace elements, such as cadmium, indium and germanium, which are called dispersed elements. These metals have important uses in the electronic industry. We also extract these dispersed elements and smelt them into metals when extracting the main elements. Chemical raw materials: fluorite can be extracted to make hydrofluoric acid, and pyrite can be made into sulfuric acid. Agriculture: As a fertilizer for increasing agricultural production, except for some synthetic fertilizers, potassium salt is used as potash fertilizer and apatite is used as the source of phosphate fertilizer. Using the physical and optical properties of minerals: calcite, quartz and fluorite were first used as prisms in optical instruments, and later many minerals were found to have special optical properties. 1960 found that gemstone (corundum) can be used as a key material for laser emission. CdS single crystal has special photoelasticity and can be used in radar. Color molybdenite has acousto-optic effect, which can produce light diffraction under the action of sound waves. Scheelite and turquoise have discoloration effect. Scheelite is white in sunlight and purple in ultraviolet, while turquoise is green in sunlight and red in light, which can be used for laser holographic recording and storage. Sphalerite single crystal is used as ultraviolet semiconductor laser material. Electronic characteristics: Copper is the most common conductive material in wires. Diamond 2 is an important semiconductor instrument. Galena can be used as the main photoelectric conversion material in near infrared, which is mainly used in satellite detection, military reconnaissance, medical thermal imaging instruments and other fields. Time is piezoelectric, which is mostly used in radar, communication, microprocessor and so on. Mica and talc can be used as insulating materials. Mechanical properties: mainly used as grinding and cutting materials, minerals with hardness greater than Mohs 7 can be used, among which diamond has the highest hardness, followed by corundum, topaz and Yingshi. Other properties: Asbestos can be used as thermal insulation materials due to its low thermal conductivity, and products such as asbestos board can be used as thermal insulation materials. Minerals with high melting point, such as mullite, can be used as raw materials for refractories. Zeolite, attapulgite, montmorillonite, palygorskite, sepiolite and other minerals can remove toxic elements and heavy metals from wastewater. They are a kind of filter material that can absorb impurities in gas and liquid, such as beer, and are important raw materials for water pollution control. Some minerals can also be used as traditional Chinese medicine, such as gypsum, cinnabar and borax. Gems and jade have become precious decorations because of their dazzling brilliance and high value. How minerals are formed Minerals are the products of various geological processes in nature. Geological processes in nature can be divided into endogenesis, exogenesis and metamorphism according to their nature and energy sources. Endogenous energy comes from the earth, such as volcanism and magmatism; Exogenous effect is the effect of solar energy, water, atmosphere and biology (including weathering and sedimentation); Metamorphism refers to the change of minerals formed at a certain temperature and pressure. Under these three conditions, minerals are formed in three ways: gas becomes solid, and the volcano emits sulfur vapor or H2S gas. The former can be directly sublimated into natural sulfur due to the sudden drop of air temperature, and H2S gas can react with O2 in the atmosphere to generate natural sulfur. The natural sulfur thus formed exists in Datun Volcano Group and Guishan Island in Taiwan Province Province, China. The transformation from liquid to solid is the main way of mineral formation, which can be divided into two forms. (1) evaporates and crystallizes from the solution. In Qaidam Basin, Qinghai, China, due to the long-term evaporation of salt lake water, salt lake water is constantly concentrated and saturated, from which many salt minerals such as halite are crystallized, which is the way of formation. (2) cooling and crystallizing from the solution. The magma melt under the crust is a kind of high-temperature silicate melt with extremely complex composition (its state is like molten steel in a steelmaking furnace). In the process of rising, the temperature decreases continuously, and when the temperature is lower than the melting point of a mineral, it crystallizes to form a mineral. As the temperature drops, all the components in the magma crystallize to form a series of minerals. Generally, minerals with high melting point are crystallized into minerals first. The change from solid to solid is mainly from amorphous to crystalline. The lava flow from the volcano cooled rapidly, and it was too late to form crystalline minerals, but became amorphous volcanic glass. After a long time, these amorphous bodies can be gradually transformed into various crystalline minerals. The minerals formed by colloid coagulation are called colloid minerals. For example, river water can carry a lot of colloid and meet seawater at the outlet. Because seawater contains a lot of electrolytes, the colloids in river water gel to form colloidal minerals, which is how oolitic hematite in coastal areas is formed. Minerals are formed under certain physical and chemical conditions. When the external conditions change, the original minerals can change to form another new mineral, such as pyrite, which can form limonite after passing through water and atmosphere on the surface. References:

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