Brief introduction of granite, magnetite and chronology?

A deep acidic igneous rock. Commonly known as granite. The content of silicon dioxide is more than 70%. The color is lighter, and grayish white and flesh red are more common. It is mainly composed of dark minerals such as quartz and feldspar and a small amount of biotite. The timely content is 20% ~ 40%, and alkali feldspar is more than plagioclase, accounting for more than 2/3 of the total feldspar. Alkali feldspar is a variety of potash feldspar and albite, and plagioclase is mainly albite or albite. The dark mineral is mainly biotite with a small amount of amphibole. Having granite structure or porphyritic structure. According to mineral types, it can be divided into biotite granite, muscovite granite, amphibole granite and mica granite. According to the structure, it can be divided into fine-grained granite, medium-grained granite, coarse-grained granite, porphyritic granite, porphyritic granite, geode granite and gneiss granite. According to the accessory minerals, it can be divided into cassiterite granite, niobite granite, beryllium granite, lepidolite granite and tourmaline granite. Ordinary petrochemical, Yunyinghua, electro-petrochemical and other automatic deformation. Granite is a widely distributed rock, which has been produced in various geological ages. The forms are mostly bedrock, rock plant, rock bell and so on. In terms of genesis, some people think that granite is the result of condensation crystallization of granite slurry in the deep crust or crystallization differentiation of basaltic magma, while others think that granite is the result of deep metamorphism and metasomatism. Many nonferrous minerals such as copper, lead, zinc, tungsten, tin, bismuth and molybdenum, precious metals such as gold and silver, rare metals such as niobium, tantalum and beryllium, and radioactive elements such as uranium and thorium are all related to granite. Granite is a kind of high quality building stone with uniform structure, hard texture and beautiful color.

Granite is a kind of deep acid igneous rock. The content of silicon dioxide is more than 70%. Light in color, usually grayish red. It is mainly composed of dark minerals such as quartz and feldspar and a small amount of biotite. The timely content is 20%-40%, and alkali feldspar accounts for more than 2/3 of the total feldspar. Alkali feldspar is a variety of potash feldspar and albite, and plagioclase is mainly albite or albite. The dark mineral is mainly biotite with a small amount of amphibole. It has typical granite structure or porphyritic structure. According to mineral types, it can be divided into biotite granite, muscovite granite, amphibole granite and mica granite. According to the structural structure, it can be divided into fine-grained granite, medium-grained granite, coarse-grained granite, porphyritic granite, porphyritic granite and geode granite. According to the accessory minerals, it can be divided into cassiterite granite, niobium-bearing iron granite, beryllium-bearing granite, lepidolite granite and tourmaline granite. Granite is a widely distributed rock, which has been produced in various geological ages. The forms are mostly bedrock, rock plant, rock bell and so on. In genesis, some people think that granite is formed by condensation crystallization of granite slurry in the deep crust or crystallization differentiation of basaltic magma. Others believe that it is the result of regional metamorphism and metasomatism leading to granitization. Many nonferrous minerals such as copper, lead, zinc, tungsten, tin, bismuth and molybdenum, precious metals such as gold and silver, rare metals such as niobium, tantalum and beryllium, and radioactive elements such as uranium and thorium are all related to granite. Granite has a uniform structure and a hard texture. The compressive strength varies with the variety and origin of stone, which is about 1000-3000 kg/cm. Granite is not easy to weather, beautiful in color, and its appearance can be maintained for more than 100 years. Because of its high hardness and wear resistance, it is not only used as high-grade building decoration engineering and hall floor, but also the first choice for open-air carving.

Resource situation

Granite rock mass accounts for about 9% of China's land area, reaching more than 800,000 square kilometers, especially in the southeast of China, where a large area of granite rock mass is exposed, showing its large reserves. According to incomplete statistics, there are about 300 kinds of granite stones. The better colors are listed as follows:

● Red series: Sichuan Red and China Red in Sichuan; Guangxi Cenxihong; Imperial concubine red and orange red in Lingqiu, Shanxi; Rushan Red and General Red in Shandong.

● Black series: Inner Mongolia Black King Kong, Chifeng Black and Fish Scale Black; Jinan black, etc.

● The green series are: Shandong Taian Green; Bean green and light green in Shanggao, Jiangxi; Blue background and green flowers in Suxian County, Anhui Province; Green in Zhejiang, Sichuan and Henan.

● Flower series: Chrysanthemum green, Snow green and Yunlimei in Yanshi, Henan; Black flowers on a white background in Haiyang, Shandong.

The chemical composition of magnetite is Fe3O4, and its crystal is an oxide mineral with equiaxed crystal system. Crystals are usually octahedral and rhombic dodecahedron, and aggregates are granular or massive. A complete single crystal is octahedron or rhombic dodecahedron. When it is a rhombic dodecahedron, it often has stripes parallel to the diagonal direction of the crystal plane. Aggregates are dense blocks or granules. The color is iron black, the streaks are black, metallic or semi-metallic luster, opaque and cleavage-free, with a Mohs hardness of 5.5-6 and a specific gravity of 4.8-5.3. Because of its strong magnetism, China was also called magnet, magnetite and Xuan Shi in ancient times. It has the strongest magnetism among minerals and can be attracted by permanent magnets. China's ancient compass "Sina" was made by using this feature. It becomes hematite or limonite after oxidation.

Magnetite is widely distributed and has many causes. Magmatic deposits occur in metamorphic and endogenetic deposits, which are typical in Kiruna, Sweden. The direct formation of pulp related to volcanism is a typical feature of Lac iron mine in Chile. The iron ore formed by contact metamorphism is representative in Daye Iron Mine, China. The iron ore formed by regional metamorphism of iron-bearing sedimentary rocks is low-grade and large-scale, and has a large amount of output in Russia, North America, Brazil, Australia, China, Liaoning and Anshan. Magnetite is the main mineral raw material for ironmaking and also a traditional Chinese medicine.

[Crystal Chemistry] Theoretical composition (WB%): FeO 3 1.03, Fe2O3 68.96. The isomorphism of Fe3 replaces Al3, Ti4, Cr3, V3, etc. The substitutes for Fe2 are Mg2, Mn2, Zn2, Ni2, Co2, Cu2, Ge2, etc.

When Ti4 replaces Fe3, it is accompanied by Fe2 —Fe3, Mg2 —Fe2 and V3-Fe3; Ti can also exist in fine inclusions of ilmenite or ilmenite spar in the form of directional association and be dissolved by solid solution. At > 600℃, a complete solid solution of magnetite Fe2O4—Fe2TiO4 is formed, and the mineral structural formula is Fe3 [Fe21-xfe31-2xti4x] O4 (0 ≤ x ≤ 0.2). Fe3 1.2-xfe2x-0.2[Fe2 1.2 Fe3 0.8-xTi4 x]O4(0.2≤x≤0.8)； Fe3 2-2 xfe2x- 1[Fe2 2-xTi4 x]O4(0.8≤x≤ 1)； Wherein the cation in square brackets is octahedral coordination. At > 500℃, a complete solid solution of Fe2O4—FeTiO3 is formed. As the temperature decreases, the solid solution dissolves.

When Ti4 replaces Fe3, among them, TiO2? 8? 725% is called titanium magnetite, TiO2? 8? 925% of them are called titanomagnetite. When it contains more vanadium and titanium, it is called vanadium-titanium magnetite. Chromium-containing minerals are called chromite magnetite. Titanium magnetite and vanadium-titanium magnetite form solid solution at high temperature and dissolve at low temperature. It can be seen in the optical slices that the micro-directional association of ilmenite generated in magnetite particles often splits along the octahedron of magnetite, which is called ilmenite. Fe2 in magnetite can be replaced by Mg2 to form a complete isomorphic series of magnetite-magnesite.

[Configuration] Isoaxial crystal system, a0 = 0.8396nm；; Z=8. Anti-spinel structure. That is,1/2f3 and all Fe2 occupy octahedral positions, and1/2f3 occupies tetrahedral positions. The lattice constant a0 decreases with the increase of substitution amount of Al3, Cr3 and Mg2. It increases with the increase of substitution amount of Ti4 and Mn2.

Hexahedral crystal, Oh-m3m(3L44L36L29PC). Crystals are usually octahedral and rhombic dodecahedron. On the rhombic crystal face of the rhombic dodecahedron, there are often stripes parallel to the diagonal direction of the face length, which are similar and stripes (Figure 4-4-3). According to spinel law. Aggregate is usually a dense granular block.

[Physical Properties] Black. The stripes are black. Semi-metallic to metallic luster. Opaque. There is no cleavage, and sometimes ∑ cleavage can be seen, which is often caused by the directional arrangement of micro-ilmenite and titanomagnetite inclusions in the {11} direction. Sexually fragile. The hardness is 5.5~6. The relative density is 4.9~5.2. Strong magnetism, Curie point (Tc)578℃. Curie point is the thermomagnetic effect of magnetic minerals, and it is the critical temperature at which magnetic or diamagnetic substances are transformed into paramagnetic material when heated.

[occurrence and combination] occurs in a relatively reduced environment. The main genetic types are:

Magmatic type; Contact metasomatism type; High temperature hydrothermal type; Regional metamorphic type.

[Identification] Octahedral crystal shape, black, black stripes, no cleavage, strong magnetism. It can be distinguished from chromite, wolframite and hausmannite and other similar minerals.

[Industrial Application] is the most important and common iron ore mineral. Titanium magnetite and vanadium-titanium magnetite are also important ore minerals of titanium and vanadium. Rich in titanium, vanadium, nickel, cobalt and other elements, can be comprehensively utilized.

Medical magnetite is a famous magnet, which is also called Xuan Shi, Magnetite, Lingshi, Magnetite and Needle Magnetite. Efficacy: subduing yang and calming the nerves; Hear and see clearly; Take a deep breath to relieve asthma.

Magnetite is widely distributed and has many causes. Kiruna, Sweden is a typical magmatic deposit. The Laco iron mine in Chile is directly formed by the pulp related to volcanism. The iron ore formed by contact metamorphism can be taken as an example in Daye Iron Mine, China. Iron ore formed by regional metamorphism of sedimentary iron-bearing strata (such as iron ore in Anshan, China) is mainly magnetite and hematite, which is the most important source of iron ore in the world with large scale but low grade. The former Soviet Union, North America, Brazil and Australia all have such large iron mines. Magnetite can also be enriched in riverbed or coastal sand because of its large specific gravity and strong weathering resistance. It can be transformed into hematite after oxidation; If it keeps its original shape, it is called pseudohematite.

The main component of timely sandstone is timely, with a density of 2.65g/cm2 and a Mohs hardness of 7. Its crystal belongs to 60 thousand crystal system, and its appearance is white, bluish gray and grayish white. Mainly used in glass products, foundry industry, metallurgical industry, ceramic uranium surface, refractories, cement industry, chemical industry and so on.