1. high crystal: also known as β crystal, it can exist stably in the range of 573~870 degrees, and it can also exist above 870 degrees, but it is unstable. 2. Crystals: also known as α crystals, can exist stably at temperatures below 573 degrees. According to the crystal crystallization, the crystal is as small as several tons, which can be divided into columnar, cluster and cave. 1. crystal column: single crystal, the maximum weight can reach several tons. There are obvious growth marks on the surface of rock crystal column. The single crystal columns sold in the market are all polished, decorated and polished, so the surface is very smooth and angular. 2. Crystal clusters: Crystal clusters exist, with different sizes, shapes and directions. 3. Crystal Cave: Amethyst is often produced in lava flow caves, forming crystal caves ranging from several kilograms to hundreds of kilograms or even tons. It is best to have beautiful and special shapes, large and uniform crystals, deep purple color, or split in the middle to match without cracking. According to the crystal appearance, it can be divided into single-pointed crystal, double-pointed crystal, dynamic crystal, pagoda crystal and bone crystal. 1. Single-point crystal: a crystal with only one terminal. 2. Double-pointed crystal: a crystal with two complete terminals. 3. Power crystal: The later grown crystal wraps the previous crystal, forming a crystal with a small bottom and a large top. 4. Pagoda crystal: The crystal that grows later wraps the crystal in front to form a crystal with a big bottom and a small top. 5. Skeleton crystals: Some crystals grow irregularly. If they grow particularly rapidly along the corner tops or crystal edges, there will be relatively concave crystal defects in the center of the crystal plane, so "trapezoid" or "protrusion" will often appear in appearance, resulting in funnel-shaped crystals or striped crystals, and triangular holes will occasionally be seen on the diamond surface at the crystal terminal, and so on. Generally speaking, crystals are distinguished by color and inclusion in business. It can be divided into the largest crystal: 1. Water bladder crystal: The crystal contains liquid and bubbles. 2. Abnormal crystals: crystals contain various colors of volcanic ash mud and other minerals and impurities. 3. Crystallization: the crystals contain needle-like inclusions, some of which are golden red; Some are black; Some are green. These are collectively called net rutile, also called hair crystal or grass crystal. The gold and red needles are rutile, also called Wiener crystals. Green needle is actinolite, also called Sidious hair crystal. The black needle is a seal. 4. Ghost crystal: In the crystal, you can see layers of terminal gray shadows or green shadows, like layers of mountains or cliffs, which are called ghost crystals. 5. Transparent crystal: Crystal crystal is transparent and colorless. 6. Milk crystal: The crystal is white because there are many bubbles and liquids, which are often found in hydrothermal veins at the head of pegmatite. 7. Amethyst: The crystal is purple, transparent to translucent because it contains a small amount of iron ions, and turns white when heated to about 300 degrees; Heating to 400 degrees to turn yellow; But if it is irradiated by X-rays or alpha particles, it will turn purple again. 8. Topaz: The crystal contains molten iron containing colloid. 9. Amethyst: Purple and yellow crystals appear in the same crystal. 10. Smoke crystal: The crystal is brown due to aluminum, from light brown to dark brown. Also known as tea crystal. Those whose colors range from dark to almost black are called black crystals or ink crystals. 1 1. rose crystal: the crystal is composed of a small amount of manganese or titanium, transparent to translucent, and sometimes extremely pale pink, also known as powder crystal or hibiscus crystal. It is usually massive in pegmatite, with many cloud-like cracks inside, and well-crystallized rose crystals are extremely rare. 12. Green crystal: Most amethysts are formed by heating. 13. Halo crystal: If there are cracks, cracks or cracks in the crystal, it will cause light refraction, thus forming an irregular rainbow image, also known as rainbow crystal.