The main composition of quartz and crystal is SiO₂.
Quartz
Quartz is a mineral with very stable physical and chemical properties. The crystal belongs to the oxide mineral of the trigonal crystal system, namely low-temperature quartz (a-quartz), which is the most widely distributed mineral species in the quartz group minerals. Quartz in a broad sense also includes high-temperature quartz (b-quartz). Quartz block, also known as silica, is mainly used to produce quartz sand (also known as silica sand), as well as a raw material for quartz refractories and firing ferrosilicon.
The chemical formula of quartz is SiO₂, which often contains a small amount of impurities such as Al₂O₃, IMO, CaO, MgO, etc. Veined quartz, quartz sand, quartzite, sandstone, silica, opal, diatomaceous earth, etc. used as raw materials for daily ceramics, rice shell ash is also rich in SiO₂. The appearance of quartz is often white, milky white, gray and translucent, with a Mohs hardness of 7, and the section has glass or fat luster. The specific gravity varies from crystal type to 2.22-2.65.
Quartz is a non-plastic raw material. The mullite crystals generated by the clay at high temperature endow the porcelain with higher mechanical strength and chemical stability, and can increase the translucency of the body. It is a good raw material for white glaze.
1、 Properties and structure of quartz sand
Quartz sand is a hard, wear-resistant, and chemically stable silicate mineral. Its main component is SiO₂. The color of quartz sand is milky white or colorless and translucent. The hardness is 7, it is brittle and has no cleavage. It has a shell-like fracture. Grease luster, relative density is 2.65, its chemical, thermal and mechanical properties have obvious anisotropy, insoluble in acid, slightly soluble in KOH solution, melting point 1750℃.
Quartz can be divided into ordinary quartz sand, refined quartz sand, and special refined quartz sand according to its quality.
2、 Application and function of quartz sand
Quartz sand is an important industrial mineral raw material, widely used in glass, casting, ceramics and refractory materials, metallurgy, construction, chemical industry, plastics, rubber, abrasives and other industries.
Crystal
Crystal is a colorless and transparent quartz crystal mineral. Its main chemical is silica, which is the same substance as ordinary sand.
When the crystal of silicon dioxide is perfect, it is crystal; when silicon dioxide is gelatinized and dehydrated, it is agate; when the water-containing colloid of silicon dioxide is solidified, it becomes opal; when the crystal grain of silicon dioxide is less than a few microns, it forms chalcedony, flint and secondary Quartzite.
The perfectly crystallized crystals belong to the hexagonal crystal system, often in the shape of hexagonal prisms. The cylinders are pointed at one or two ends, and a number of long cylinders are connected together. They are generally called crystal family, which is beautiful and spectacular. Silica crystals are incomplete, and the shapes can be described as varied. When you go to the Hainan Crystal Exhibition Hall to take a look, you can have an eye-opener: in addition to the common long columnar shape, there are also sword-like shapes, some are like plates, some are like short columns, and some are like double cones. Some are as small as a finger, some are as big as a boulder; some are less than half a dozen, and some weigh more than 300 kilograms.