Jiuyan shale is mainly silica, accompanied by iron oxide, agate, crystal, basalt and timing. The hardness is high, and the structure of some areas is dense, but the associated areas are usually loose, fragile and lack of toughness, which is not conducive to carving, grinding and polishing, and is mostly used to make round beads or buccal tablets.
Classification of natural dzi beads:
1, round plate bead (also called eye stone, eyeball, eye plate bead, etc. ).
2. Pharmacist beads (mostly natural and artificially etched).
3. Silk-wrapped agate (many commercial aliases).
4.Pharma dzi beads (once the Himalayan region was an ocean, Pharma dzi beads were once fossils of aquatic organisms and were regarded as sacred because of their roundness).
5. Silicified wood (some trees in desert areas can be jadeite, and a few have rings on them, which can be polished into accessories).
6. Money stone.
Classification of artificial dzi beads:
Artificial dzi beads are called "inlaid agate", "inlaid chalcedony", "etched agate" and "etched chalcedony" in theoretical circles. Because the ancestors did not know the difference between monocrystalline silicon dioxide and polycrystalline silicon dioxide, there is no difference between agate and chalcedony, hereinafter referred to as agate.
1, according to the etching materials, it can be divided into alkali etching agate bath pickling agate. Nitric acid for pickling and vegetable alkali for alkali etching.
2. According to the place of origin, it can be divided into Tibetan dzi beads (black lines are painted after white etching), West Asian dzi beads (white lines are etched on red chalcedony), Indian dzi beads (white lines are painted after black etching, such as "Zhu Shou" on turtle back) and Nepalese dzi beads (black and white lines are alternately etched on transparent agate).
3. According to the division of network scholars, it can be divided into pure system, collapse system and impact system.
4. The five-point method of Dr. 4.Nebesky Wolkowitz in his paper "Prehistoric Beads in Tibet".
To sum up, the dzi bead should be a natural and beautiful stone excavated by people's "eye worship" or "circle totem", which makes the body comfortable due to psychological effects when worn. Under the influence of faith, the ancestors wore them in large quantities, which led to a shortage of goods, and then tried artificial etching. At this point, artificial dzi beads were formed.