The mass fraction of SiO2 in the crust is as high as 60%-65%. SiO2 exists in two categories: crystalline and amorphous, collectively known as silica.
Silica natural minerals usually include crystalline silica mineral quartz, gangue quartz, powder quartz and amorphous mineral diatomite.
The silica crystal structure is a continuous framework of SiO4 (silicon-oxygen tetrahedron), where each oxygen is shared between the two tetrahedrons, giving the total chemical formula for SiO2.
In addition, silica includes not only natural minerals, but also a variety of synthetic products. The synthetic products are mainly white carbon black (amorphous silicon dioxide), including fumed white carbon black (fumed silicon dioxide) and precipitated white carbon black (precipitated silicon dioxide).


silicate
A general term for a compound composed of elements such as silicon, oxygen, and metal elements. Most silicates are insoluble in water, a few are soluble, the most common soluble silicate is: Na2SiO3, commonly known as water glass, paucine.
Silicate composition: active metal oxide - more active metal oxide - silica - water. Kaolinite Al(Si2O5)(OH)4, magnesium olivine Mg2SiO4, calcium zeolite Ca(Al2Si3O10)▪3H2O, mica KAl2(AlSi3O10)(OH)2 and so on all belong to silicate.
The three traditional silicate industries are: glass, ceramics and cement.

quartz
Silica in the crust is mainly in the form of minerals such as Quartz, which is second only to feldspar in the crust, accounting for 12.6% of the weight of the crust.
According to the morphology of quartz, it can be divided into three categories: crystalline phanerocrystalline quartz, cryptocrystalline quartz/micrystalline quartz and amorphous quartz.
Different forms of quartz (SiO2)
Depending on the crystal structure of natural crystals, there are three polymorphic variants of quartz: quartz, squamite and cristobalite.
According to the temperature of mineralization, the three polymorphic polymorphs were divided into α and β groups, with a total of seven polymorphs. High temperature β quartz formation temperature is greater than (573-870 ℃), belongs to hexagonal crystal system; The formation temperature of low temperature α quartz is lower than 573℃, which belongs to trigonal crystal system.


Polycrystalline transformation of quartz
In addition, there are several synthetic variants of SiO2, such as Coesite, Stishovite, Keqtite, and W-SiO2(also known as fiber silica). And we often say that the common quartz is low-temperature alpha quartz.


At present, the quartz mineral resources that can be used as industrial applications are mainly seven industrial types of mineral deposits: natural crystal, quartz sandstone, quartzite, gangue quartz, powder quartz, natural quartz sand and granite quartz


Application of silicon-quartz
From natural sand to quartz watches in life, from crystal agate to simple and elegant ceramics, from industry to science and technology, from atoms to space... These are silicon-centric substances. Silicon is arguably nature's most versatile material.
Quartz silicon industry is one of the most important industries and quartz is one of the most important mineral resources in the silicon era
A notable feature of the industrial application of quartz mineral raw materials is the simultaneous existence of three forms: the use of the inherent physical and chemical properties of mineral crystals, such as 3D printed sand, crystalline silicon powder, etc.; Provide useful chemical composition, is the most basic raw material of silicate materials; Si is the only raw material for metal silicon and its purified products, polysilicon and monocrystalline silicon.
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