Rock Crystal is a quartz (Quartz) crystal mineral. Its main chemical component is silicon dioxide, and its chemical formula is SiO2. Western countries believe that anything that is transparent is crystal, so the word crystal includes colorless and transparent glass (K9 category, ordinary glass turns blue), and also includes natural crystal ores.
There are more than ten names for crystals in ancient China, such as Shui Jing, Shui Bi, Shui Jade, and Quartz. Therefore, in order to facilitate the distinction, natural crystals are usually referred to as (Rockcrystal) in the world. Well-developed single crystals are hexagonal pyramids, so they are usually lumpy or granular aggregates. They are generally colorless, gray, milky white, and appear purple, red, smoke, tea, etc. when containing other mineral elements.
Formation:
The formation conditions of crystal are more demanding than those of ordinary quartz. First, there needs to be sufficient and stable growth space; secondly, there needs to be hydrothermal fluid rich in siliceous minerals, which is slightly alkaline and has low salinity; thirdly, it needs a lower temperature (160 0C -400 0C, medium First, high pressure (2-3 atmospheres); fourth, a certain growth time is required to produce crystals.
In nature, the joints, cracks and faults that develop are the growth of crystals. Good space. Granite has strong development or metamorphism and can provide sufficient hydrothermal fluid. This hydrothermal fluid itself has better temperature and pressure and is easier to obtain, so crystal production is more widespread on the earth.
Crystals are often produced in the form of crystal clusters and geodes. Crystal caves generally exist in the gas or hot water contained in the thick lava flow layers formed by volcanic eruptions. Dissolution and other processes lead to the emergence of a large number of pores in rock formations. When fluids rich in siliceous minerals enter the thin lava pores, and when the temperature and pressure conditions are suitable, minerals such as crystals will crystallize and precipitate.
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Origin of crystals: Endogenous crystal deposits include pegmatite type, hydrothermal type and skarn type; exogenous deposits are common in placers, and gem-quality crystals are mainly produced in geodes or geodes. In pegmatite veins, crystals are produced in almost all parts of the world, such as Madagascar, Zambia, Brazil, Germany, Russia, Myanmar, Afghanistan, etc.
China’s crystal deposits are also widely distributed, with 25 deposits. The above provinces and regions all have crystal output. The origin types of crystal deposits in China are mainly divided into four types:
1. Granite pegmatite crystal deposits, such as Chasitai, Wulatezhong Banner, Inner Mongolia. Crystal deposits;
2. Quartz vein type crystal deposits, such as the most famous "Crystal Hometown" in my country - the crystal deposits in Donghai County, Jiangsu Province;
3. Skarn Type crystal deposits, such as the Chaoyang Bay Crystal Deposit in Bahrain Right Banner, Inner Mongolia;
4. Crystal placer deposits have high crystal hardness and are not easily weathered, and often form residual, slope and alluvial crystal placers.
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Reference: Baidu Encyclopedia-Crystal