Chemical composition and properties of crystal: chemical formula is SiO2. Pure colorless and transparent crystal is a variety of seasonable. The chemical composition contains 46.7% silicon and 53.3% oxygen. Because it contains different mixtures or mechanical mixtures, it has many colors. Purple and green are caused by iron (Fe2+) ions, purple can also be caused by titanium (Ti4+), and other colors are caused by color centers. The crystals contain sandy and fragmented goethite, hematite, rutile, magnetite, garnet and chlorite. Hair crystals are formed by inclusions containing hairy needle-like minerals visible to the naked eye. Containing manganese and iron is called amethyst; Iron (golden or lemon) is called topaz; Rose color containing manganese and titanium is called rose season; Smoke color is called smoke crystal; Brown is called tea crystal; Black and transparent are called ink crystals; The light green one is called stone pulp. Crystal structure and morphology: It belongs to ternary system. The crystal is prismatic, with a hexagonal cone, the cylinder has horizontal stripes, and amethyst often has angular stripes. In nature, crystals are often produced in groups with beautiful shapes. . Physical properties of crystal: the crystal is colorless, purple, yellow, green and smoky. Glass luster. Transparent to translucent. Hardness 7. Sexually fragile. The specific gravity is 2.65. No cleavage. Shell fractures also have good herringbone fractures with equal ridges. Amethyst has obvious dichroism, while topaz and tea crystal have weak dichroism. Light emitting crystals have strong phosphorescence. Green gold placer crystal emits gray-green fluorescence under long-wave and short-wave ultraviolet irradiation. It has cat's eye, rainbow and placer gold effects. The crystal is piezoelectric. Basically, in rock crystals, the most important component of crystals is "silicon dioxide", which is also the most important mineral occupying more than 65% of the earth's crust. It also contains various trace metals, so it will cause crystals of different colors; Moreover, crystals are widely associated with various minerals in nature, such as mica, feldspar, calcite, tourmaline, rutile, granite and so on. The growth environment of crystals is mostly underground and caves, which requires rich underground water sources, and groundwater mostly contains saturated silicon dioxide. At the same time, the pressure inside it needs to be about two to three times that of atmospheric pressure, and the temperature needs to be between 550 and 600℃. If given a proper time, the crystal will crystallize into hexagonal columnar crystals according to the natural law of hexagonal crystal system. Usually, in the ideal environment controlled by human beings, that is, when the physical and chemical conditions meet the above conditions, the growth rate of crystals is about 0.8 mm per day. This is also the standard production speed of many intraocular lenses in laboratories and factories. The crystal thus cultivated is the so-called "synthetic Shi Ying", which is usually cut into chips and used in electronics, computer and communication industries. Some people call it "breeding Shi Ying". Although they use different words, they actually mean the same thing. Generally, the thickness of industrial intraocular lens is about 3 cm, that is, 30mm, and it takes about 40 days to grow. It generally takes about180 days for jewelry industry to grind a crystal ball with a size above 10 cm (100mm). However, this speed is only possible in the most ideal environment controlled by human beings. In nature, the situation is not so optimistic because of raw materials, water quality, temperature, pressure and other conditions. Are constantly changing, it is difficult to achieve the ideal situation. It usually takes tens of thousands or millions of times to achieve the same growth. This is the reason why the "geological age" movement takes "million years" as the calculation base, and it is also the precious place of "crystal rock".