Jinan black granite precision components manufacturer
According to the classification of petrology, granite in narrow sense refers to the acid intrusive rock formed by magmatic intrusion with quartz (20% - 60%), alkali feldspar and plagioclase as the main minerals. In a broad sense, granite refers to a set of intrusive rock assemblages with the appearance of granite.
Granite is a kind of widely distributed rock, which is produced in every geological age. Most of them are batholith and rock strain. In terms of Genesis, some people think that granite is formed by condensation crystallization of granite magma in the deep crust or crystallization differentiation of basaltic magma, and others think that it is the result of granitization caused by deep metamorphism and metasomatism.
2、 Petrological characteristics of minerals
The content of SiO2 is more than 70%. The color is lighter, gray white and flesh red are more common. It is mainly composed of quartz, feldspar and a small amount of biotite and other dark minerals. Quartz content is 20% - 60%. Feldspar is divided into alkali feldspar and plagioclase, alkali feldspar is more than plagioclase, accounting for more than 2 / 3 of the total feldspar. Alkali feldspar is a variety of potassium feldspar and albite, plagioclase is mainly albite or feldspar. The dark mineral is mainly biotite with a small amount of hornblende. Having a granitic or mottled structure. Blocky structure is the most common, but there are also patchy structure, crystalloid structure and gneissic structure.
Granite rocks have high wear resistance and mechanical strength. The compressive strength of fresh granite is generally (1000-2100) × 105Pa, with a maximum of 3000 × 105Pa; the flexural strength is generally (90-270) × 105Pa, with a density of 2.63-2, a bulk density of 2.50-2, a porosity of about 1.2%, and a water absorption of about 0.46%.
Granite is often closely related to the genesis of endogenetic metal deposits such as nonferrous metals, rare metals, radioactive elements, etc. there are many kinds of deposits. It is an important building material, with high strength, high hardness, wear resistance, corrosion resistance and other excellent physical properties and decorative effects, which has brought great economic value. Therefore, its application has been paid more and more attention. The application of granite in stone is expanding, not only for luxury public buildings, but also for home decoration.
As a kind of stone material, granite is mainly used in the following aspects: building materials, art decoration, carving materials, paving, water conservancy engineering, bridge engineering, port dike, ground foundation and other engineering materials, chemical, light industrial products, measuring instrument components for astronomy, earthquake, aviation industry, in addition, it has been widely used in living appliances, environmental protection and other aspects.
4、 Geological characteristics
The types of granite deposits in China are complex and various. The proven and developed granite deposits can be generally divided into magmatic granite deposits and metamorphic granite deposits, which provide a broad prospect for the exploration of granite deposits in China.
（1） Magmatic granite deposit
The high temperature magma intrudes into different parts of the earth's crust and is formed by condensation and crystallization. It has a sudden intrusive relationship with the surrounding rock and has the structural characteristics of condensation and formation of a typical high temperature melt.
Such deposits include a series of ultrabasic, basic, neutral and acid intrusive rocks and volcanic rocks, which are distributed in all major geological structural units in China, mainly in fold belts. The age of formation can be divided into Precambrian, Caledonian, Hercynian, Indosinian, Yanshanian and Himalayan. Representative deposits include Shouning granite mine, Miyun Precambrian hornblende Diopside in Beijing, tuff in Jinyun, Fujian, purplish red tuff in Minhou, Fujian, and purplish red banded rhyolite in Yongtai, Fujian.
（2） Metamorphic granite deposit
Metamorphic or metasomatic granite deposit is a kind of granite deposit in the deep metamorphic rock series. The granite ore body is a kind of deep metamorphic rock formed by the strong metasomatism of the original rock under the regional metamorphism and the gradual transformation of the rock in composition, structure and structure. Among them, migmatite, gneiss and migmatized granite can be used as granite. The metamorphic granite deposits are mainly distributed in the North China platform area. The ore-forming age is mainly in the aether Paleozoic. The ore bearing rock series include Fuping group in Taihang mountain area, Taishan Group in western Shandong, Dengfeng group in Songshan Mountain, Sanggan group in Yanshan mountain, Anshan Group in Eastern Liaoning Province, etc. The ore body has a large exposed area and is distributed in strips and zones. The lithology is mostly acid or alkaline migmatized or potash granite series. It has a common gneissic structure. The rock is red, uniform in structure or beautiful in pattern, which can meet the requirements of famous and excellent stones. Representative deposits include the Archean migmatized gneissic granite deposit in Lingqiu, Shanxi, and the Archean migmatized granite deposit in Yanshi, Henan.
5、 Deposit distribution
Granites are widely distributed in China. Due to the complex geological conditions, multiple periods of geological tectonic movement and frequent magmatic activities, granites are produced in the main tectonomagmatic periods from Proterozoic to Neogene. It was formed in the back arc magmatic belt on the continental side of the convergence boundary between the continental plate and the oceanic plate in geological history, and often developed along the extensional deep faults of the orogenic belt. The formation of the continental crust of China has experienced a long historical process with eleven ancient plates as the core, which are continuously assembled and inlaid, and the continent is gradually accreted and expanded. In this process, the granitic magma is mainly developed in the fold orogenic belt of the continental plate on the plate subduction zone, which is controlled by the deep faults and distributed in belts, and often occurs in large-scale batholith and rock strain, forming the main body of large mountain chain, usually distributed in the fold belt