Natural Crystal (Quartz) Is a Kind of Quartz Crystal Mineral, Its Main Chemical Composition Is Silicon Dioxide, Chemical Formula Is SiO 2, Alias Crystal Water, Water Tonight, Water Jade. Well-Developed Single Crystals Are Hexagonal Cones, So They Are Usually Massive Or Granular Aggregate. Generally Colorless, Gray, Milky White, Purple, Red, Smoke (Tea), Yellow, Green, Etc. When Containing Other Mineral Elements.