The conditions for the formation of crystal are more demanding than ordinary quartz. Firstly, there needs to be sufficient and stablegrowth space; secondly, there is a hydrothermal fluid rich in siliceous minerals, which is slightly alkaline and low in salinity; thirdly, it needs a low to high temperature (160 0C -400 0C,medium A high pressure (2-3 atmospheres); Fourth, a certain growth time is required to meet these four conditions to produce crystals. In nature, the developed joints, cracks and faults are good spaces for crystal growth. Granite develops or The metamorphic effect is strong, and it can provide sufficient hydrothermal fluid. This hydrothermal fluid itself has better temperature and pressure.The time factor is easier to obtain, so the production of crystals on the earth is more extensive.
Crystals are often produced in the form of crystal clusters and geodes. Crystal caves are generally found in igneous rocks and basalts of thick lava flow beds formed by volcanic eruptions. The gas contained in the volcanic eruption or the hot water dissolution caused a large number of pores in the rock formation. When the fluid rich in siliceous minerals enters the thin lava pores and the temperature and pressure conditions are appropriate, the crystals will precipitate out of crystals, etc. mineral.
