Endogenous deposits of crystals include pegmatite, hydrothermal solution and skarn. Exogenous deposits are common in placer mines. Gem-grade crystals are mainly produced in crystal caves or pegmatite veins, and are produced almost all over the world. Such as Madagascar, Zambia, Brazil, Germany, Russia, Myanmar and Afghanistan.

China's crystal mineral deposits are also widely distributed, with crystal output in more than 25 provinces and regions. For example, the Chasitai crystal deposit in Wulate Zhongqi, Inner Mongolia, the most famous crystal town in China, and the crystal deposit in Donghai County, Jiangsu Province.

Extended data:

The conditions of crystal formation are more severe than the corresponding conditions. One is to have enough stable growth space, the other is to have hydrothermal solution rich in siliceous minerals, which is weakly alkaline and has low salinity, and the third is to have low and high temperature.

Fourthly, it takes a certain growth time to meet these four conditions to generate crystals. In nature, developed joints, cracks and faults are good spaces for crystal growth.

Granite has strong development or metamorphism, which can provide sufficient hydrothermal solution and has good temperature and pressure. Time factor is easier to obtain, so the output of crystal is more extensive on the earth.

Crystals are often produced in the form of clusters and caves, among which caves generally exist in igneous rocks and basalts, with very thick lava flow layer formed by volcanic eruption.

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