Nau's English name is Agate, which comes from the Latin word of Greek. This is the name of the Achilles River in Sicily, Latin. This is where Theophrastus first discovered agate in Italy (during the period of Dior Flatat). The word agate comes from Buddhist scriptures, and it is called "Asmagapo" in Sanskrit, which means "horse brain". The word agate was used earlier in China. You can see concentric circles, ripples, layers or parallel stripes composed of many different colors, such as gray, white, red, green, light brown and light blue. There is a saying called "a thousand agates and thousands of jade pieces". In the gem circle, the aphanitic block with concentric layered, irregular ribbon and winding structure is called agate. The chemical composition of agate is mainly silicon dioxide, which often contains trace elements such as iron, manganese and nickel. The crystal morphology is aphanitic, with granular and fibrous structure, and the aggregate is often stalactite, kidney-shaped, nodular and dense. Agate has fat or waxy luster, translucent, conchoidal fracture. The hardness is 7-7.5, and the texture is hard and wearable. There are many kinds of agates, such as striped agate, moss agate, water bile agate, cut agate and so on. Agate is one of the jades with wide distribution, tough texture, bright color and beautiful decoration in nature.

Agate is widely used. It can be used as medicine, gem, jade, jewelry, handicraft materials, abrasive tools, instrument bearings and so on. Agate is a kind of gem,> Epigraphy Volume VIII records: horse brain, agate. Slightly red, like a horse's brain, it is called agate bead, which belongs to jade and is a treasure. Agate is hard, and polishing is labor-consuming. The color is flawless and can be used as various decorations. According to historical records, wearing agate crafts is not only for decoration, but also can make people clear-headed, energetic and improve work efficiency. Agate contains a variety of trace elements, such as iron, zinc, nickel, chromium, cobalt, manganese, etc., which is beneficial to health after long-term use.

Traditional Chinese medicine believes that agate is pungent, cold and non-toxic, and can be used by people who have difficulty in ophthalmology. Grinding with agate is very effective. Medicinal agate chips are left when carving precious stones. Agate is one of the earliest familiar gem materials and has long been regarded as a rare treasure in the world. It is said that it can bring happiness and confidence to the wearer, be endowed with the mercy of God, and ensure their victory and strength. The earliest inhabitants of Mesopotamia, the Samoan, seem to be the first person to use agate as souvenirs, rings, beads, stamps and other precious stones. Their axe crafts made of agate are now stored in the National Museum of American History in new york. The most unusual agate product is a wine glass with two handles, with a capacity of more than one pint. The appearance of the cup is exquisitely carved with the design of sprinkling god Bacchus. According to historical records, this cup was made for the Roman emperor Nero, and was later owned and preserved by many people, and finally became the cup used at the coronation reception of the French king. The French think this cup is one of the most valuable souvenirs in history. Agate is mainly produced in cracks and caves of volcanic rocks and also in sedimentary rocks. The most famous producing areas in the world are India, Brazil and other places. Agate is widely distributed in China, almost all provinces, mainly in Heilongjiang, Liaoning, Hubei and other regions. The "Rain Flower Stone" produced by Nanjing Rain Flower Stone is a kind of agate. Ancient legend has it that agate is condensed from so-called "ghost blood", which is just a legend.

Agate has been decorated by people since ancient times because of its beautiful stripes. Among the unearthed jade articles, strings of agate beads are more common, mostly necklaces. There are many records about agate in China ancient books. In the history books before the Han Dynasty, agate was also called "Qiongyu" or "Chiyu". Guangya has the saying that "agate stone is second to jade" and "jade is the first jade". The word agate comes from Buddhist scriptures. Sanskrit's real name is "Asma Garbo", which means "Agate". It can be seen that after Buddhism was introduced into China, Qiongyu or Chiqiong was renamed "Agate" in China.

In addition to chalcedony, sometimes a small amount of opal or aphanitic granular time is found in the fine minerals that make up agate. Strictly speaking, without the characteristics of grain and pattern, it can't be called agate, but chalcedony. Now some chalcedony without grain and pattern on the market is also called "agate", which is inconsistent with the meaning of ancient agate. Pure agate is white. Because it contains other metal elements (such as iron and nickel), it is gray, brown, red, blue, green, emerald, pink green and black, and sometimes several colors are mixed or appear alternately. Agate blocks are transparent, translucent and opaque, with glassy to waxy luster. The hardness is 6.5 ~ 7 and the specific gravity is 2.65. There are many kinds of agates according to the thickness and shape of stripes. Those with onyx stripes are called onyx, and those with red stripes are the most precious, called red onyx. In addition, there are strip agate, city agate, Tanagate, moss agate, red agate, zygote agate, sauce agate, cypress agate, arc agate, water bile agate and other varieties (Li See Compendium of Materia Medica

In the "chalcedony" without grain and pattern, there are also many jade raw materials. According to different colors, there are "carnelian", "chrysolite" (also known as flesh color), "chrysolite", "blood chalcedony" (also known as blood stone) and "jasper". Agate, like nephrite, is a traditional jade in China. There are agate cups and agate beads in the jade unearthed from the ruins of Nanjing Beiyinyangying. Among a large number of agate beads, one is made to ward off evil spirits, with a length of 1.7 cm. Agate beads were also found in Qijia Cultural Site in Dahezhuang, Yongjing, Gansu, Chunqiu Tomb in Dadian, Junan, Shandong and Jin Dong Tomb in Xiangshan, Nanjing.

Ancient agate not only came from the western regions, India, Persia, Guo Kang, Japanese and other countries, but also from China. For example, Fuyu and Gulou in the northeast, the former is located in Siping City, Jilin Province; The latter is a national name, living in the north of Changbai Mountain, the Songhua River and the lower reaches of Heilongjiang. Known as "Chishi" since ancient times (see Book of the Later Han Dynasty). In addition, Yuzhou (now Yuxian) Jiukong Mountain and Fu Xuan (Xuanhua), Sijiaoshan (see Tiangong Wu Kai), Ningxia area of Gansu (see natural history), Shenmu and Fugu area of Yan 'an area of Shaanxi (see Guangyu Ji), Chiling Town of Ruzhou (see Song History), Bobai County of Guangxi Zhuang Autonomous Region (see now, Chinese geologists have It is not so easy to identify the source of jade unearthed from agate in ancient and modern times and at home and abroad because of its numerous origins. For example, the famous animal head agate cup in Tang Dynasty, its jade source is unclear.

There are many kinds of agate, such as mountain agate and water agate, so there are many colors, among which red is the most precious.