Jade, which belongs to the same department, is synonymous with beautiful stone in China. The ancients regarded jade as a treasure, and today people call precious jade Baoyu. China is a country of jade, but at present, there are differences in the definitions of jade, jade and precious stones in the domestic jewelry, archaeology and geology circles. At present, jade in the world refers to nephrite and jadeite (that is, jadeite, as we usually say), and other jade carving stones are collectively referred to as jade. Gem is a collection of one or more minerals with special optical effects, and most of them are single crystals of certain minerals, such as diamond, ruby, sapphire, emerald, opal, tourmaline, purple tooth black and so on. 1. Emerald1In the second half of the 9th century, French mineralogist Demoures divided China's "jade" into nephrite and jadeite (see Geological Information Institute: Foreign Geological Science and Technology of Emerald Chong, No.2, 198 1). Emerald, commonly known as "Emerald" in China, is a rising star in traditional jade in China, and also the top grade in all modern jade. Emerald, whether it is "mountain material" (primary ore) or "seed material" (secondary ore), is mainly a dense block composed of jadeite minerals. Under the microscope, jadeite minerals that make up jadeite are closely intertwined, forming a fibrous structure of jadeite. This compact fiber structure makes jadeite delicate and tough. Jadeite is composed of silicate minerals of steel and aluminum. Pure jade is colorless or white. The chemical composition of the block is: silica accounts for 58.28%, sodium oxide accounts for 13.94%, calcium oxide accounts for 1.62%, magnesium oxide accounts for 0.9 1%, iron oxide accounts for 0.64%, and it also contains trace amounts of chromium and nickel. Among them, chromium is the main factor that makes jadeite green. Usually, jadeite contains 0.2 ~ 0.5% chromium oxide, and some of them reach more than 2 ~ 3.75%. Emerald hardness 7, specific gravity 3.33. Refractive index of minerals: Ng= 1.667, NP =1.654; The discount rate is 0.0 12. Common jadeite colors are white, gray, pink, light brown, green, emerald green, yellow-green, purple and so on. Most of them are opaque, partly translucent and glassy. According to color and texture, there are more than 20 varieties, such as ruby green, brilliant green, yellow sun green, sunny green, glass green, Ying Ge green, spinach green, shallow water green, light sun green, frog green, melon skin green, plum blossom green, blue-green, gray green, oil green, violet, lotus root powder land and so on. Jade is clearly called jadeite in China, which probably started in Song Dynasty. The jadeite mentioned in Zhang Heng's Poems on Xijing, Ban Gu's Poems on Xi Du and Xu Ling's Poems on Yutai in the Six Dynasties may refer to jasper in nephrite, not jadeite. Because jadeite was not tested in the Tang Dynasty, Shan Li's Notes on Selected Works and Yan Shigu's A Visit to the History of Han Dynasty are unheard of. Recently, Joseph Needham, a British historian, said in the third volume of History of Science and Technology in China:/kloc-Before the 8th century, people in China didn't know about jadeite. Later, jadeite was imported from Myanmar to China via Yunnan. Not long ago, Soviet geologist Kivlinko also pointed out that the secondary jadeite deposits in Dumao, Panmao and Nannaimao in Myanmar were discovered in 187 1 year, and have been mined for 100 years, but they have not been mined. The primary jadeite in the Wulong Valley of Myanmar was mined as early as13rd century (late Song Dynasty and early Yuan Dynasty) (see foreign geological science and technology). However, among the palace treasures and unearthed cultural relics in China, jadeite before Ming Dynasty has not been found. Therefore, it has always been an unclear historical mystery when China people called jadeite jadeite and when Burmese jadeite was introduced to China. We expect archaeologists to make new discoveries to solve this historical unsolved case. Second, nephrite nephrite is the translation of English nephrite by China mineralogists. This English name comes from Greek, which means "kidney". This is because the ancient mainland thought that hanging this kind of jade around the waist could cure kidney disease (Jiushu Beowulf: Dictionary of Precious Metals). It seems that ancient Europeans, like ancient China people, were superstitious about jade. The ancients in China not only thought that decorating this jade could ward off evil spirits, but also thought that drinking jade powder could cure diseases. However, neither Europeans nor Mexicans and New Zealanders who like jade articles have a long history of using nephrite in China. China is called "Jade Country" in the world, which is related to the long history of discovering and utilizing nephrite. Nephrite has white jade, sapphire, jasper, topaz and jet in China. Different from jadeite, they are compact blocks composed of tremolite actinolite minerals (mainly tremolite) in amphibole group minerals. Observing under the microscope, nephrite, like jadeite, has a fibrous structure. This fibrous structure composed of tremolite or actinolite is the main reason why nephrite has fine and tough properties. Tremolite is a kind of calcium magnesium silicate containing water and fluorine, and its iron content is often less than 4%. When the iron content exceeds 4%, it will be converted into actinolite. The chemical analysis results of nephrite in Xinjiang, China are as follows: silica accounts for 57.6 o%, alumina 0.25%, iron oxide 0.66%, manganese oxide 0. 16%, magnesium oxide 25.6 1%, calcium oxide 2.68% and other impurities 2.74%. The hardness is 6 ~ 6.5. The specific gravity is 2.96 ~ 3. 17. Refractive index of minerals: tremolite is NP =1.599 ~1.619, nm =1.612 ~1.630, ng =/kloc- Actinolite is NP =1.619 ~1.688, nm = 1.630 ~ 1.697, ng =1.640 ~/kloc. The common colors of nephrite are white, gray, green, dark green, yellow and black. Most of them are opaque, and some are translucent and glassy. The varieties of nephrite are mainly divided according to different colors. The best white jade, as white as sheep fat, is called "sheep fat jade". Sapphire is grayish white to bluish white. At present, some people call it "blue white jade". Jasper is green to dark green, and sometimes black spots can be seen, which is caused by impurities such as chrome spinel minerals. Containing many impurities, when it is black, it is a precious jet. Topaz is also a precious variety. Sapphire has a yellow shell of sugar water, and some people call it "sugar jade". When white is slightly pink, some people call it "pink jade". Tiger skin color is called "tiger skin jade" and so on. As far as we know, except nephrite (including tremolite opal) produced by Toyota in Taiwan Province, it is mainly produced in Xinjiang. Hetian jade in Xinjiang has a long history, which is recorded in Historical Records, Hanshu, Shu Wei, Sui Shu, Old Tang Book, New Tang Book and History of the Five Dynasties. But before the Western Han Dynasty, there were many fairy tales about nephrite produced in Xinjiang in historical records. A few words from Li Si's Persuading Guests to Drive Away and Su Li's Letter to Zhao Haoqi Huiwen ("Your Majesty has given Kunshan jade today, and it is a treasure of harmony ... These treasures were not born in Qin. ""Great lakes dogs don't go east, the jade of Kunlun can't get out. This three treasures are not kings. " ), as early as the Spring and Autumn Period and the Warring States Period, when Qin unified the six countries, nephrite from Xinjiang had been continuously exported to the mainland from the northern foot of Kunlun Mountain and Hotan. In particular, the nephrite produced by Mildred is large in size and often weighs tens of thousands of kilograms. In the Qing Dynasty, there were three pieces of discarded jade produced in Mildai, Takutai, Houssack, the largest one was 10000 kg, the second one was 8000 kg, and the second one was 3000 kg. The original weight of "Dayu Harnessing Water and Jade Mountain" in the Treasure Hall of the Palace Museum is more than 10700 kg, which is the largest jade by far, that is, it is produced in Milwaukee. Xiuyan jade, called Xiuyu for short, was named after it was produced in Xiuyan County, Liaoning Province. On the surface, the main variety of this kind of jade is similar to sapphire or jasper in Xinjiang, but its mineral composition and hardness are different. The main mineral that makes up Xiuyu is serpentine. The composition often contains ferrous and trivalent iron, and is also mixed with impurities such as manganese, aluminum, nickel and cobalt, which makes xiuyan jade have various colors. The colors of jadeite are white, yellow, light yellow, pink, light green, green, emerald green, dark green, brown green and other variegated colors. Among them, green tones are often dominant, and the color is between sapphire and jasper. The serpentine minerals that make up Xiuyu usually account for more than 85%, and a small amount of calcite, tremolite and other minerals are common. The mixing of tremolite can increase the hardness of xiuyan jade. The five qualities of Xiuyan jade are exquisite, translucent to opaque, waxy to glossy. The hardness is 2.5 ~ 5.5 and the specific gravity is 2.5 ~ 2.8. The average refractive index of serpentine minerals is 1.54 ~ 1.55. Serpentine is an metasomatic alteration mineral of magnesium carbonate rocks, magnesium basic rocks and ultrabasic rocks, and can also coexist with talc and chlorite. Jade in xiuyan jade is easily distinguished from jadeite and nephrite, mainly because of its luster (oily luster) and hardness. In Xiuyu magnesium marble with extensive contact metamorphism, this geological environment exists in many areas of China, so its genesis is quite extensive. At present, there are several known varieties with different origins and names: jade is green, translucent to opaque, and its origin is Wagou, Xiuyan County, Liaoning Province. Chemical composition: silica 43.80%, magnesia 42. 10%, calcium oxide 0.56%, alumina 0.006%, iron oxide 0.64%, water 1 1%, and impurity 12.85%. The hardness is 4.8 ~ 5.5, and the specific gravity is 2.6 1. Dolomite marble produced in ancient strata. Jade is found in the jade of Liangzhu culture in Neolithic period in Jiangsu and Zhejiang (Jian Zheng: Study on Ancient Jade Unearthed from Neolithic Site in Wuxian County, Jiangsu Province). There are more than 40 jade articles in Fu Hao's tomb in Yin Ruins. "Most of them are close to xiuyan jade, Liaoning, a few are close to Nanyang jade in Henan, and a few are similar to Hetian jade in Xinjiang." (Xia, Wang Genyuan: History of Ancient Mining Development in China, p. 428). This shows that Xiuyu's mining history is at least three or four thousand years. The history of jade mining in South China is unknown. Because it is produced in Liu Si, Xinyi County, Guangdong Province, it is also called "Xinyi Jade". Jade is mostly composed of serpentine, and contains a small amount of phlogopite, talc, calcite, tremolite, chlorite, epidote and so on. Because of many impurities, the color is often different from Xiuyu, and the tone is dark green to brownish green. At the same time, the geological conditions are different from those in xiuyan jade. It occurs in the stratum composed of mica schist and banded mixed gneiss, and there is often a talc layer with a thickness of 0.2 ~ 5.5 meters under the jade ore body. Qilian jade is produced in Qilian Mountain, with dark green color and many black spots, which are not found in xiuyan jade and Nanfang jade. Beijing topaz is light yellow and also made of serpentine. It is named because it is produced in the contact metamorphic marble of Laojuntang in the Ming Tombs of Beijing. It was discovered in the 1960s, and it is unknown whether it has been mined in history. Mining has stopped because of too little output. Anle jade is also a serpentine jade, named after it was first discovered in Lvshui River, Ji 'an County, Jilin Province. It appears in the ancient strata of serpentine marble. Jade is pure, delicate and smooth, apple green to dark green, slightly transparent to translucent. There are many places of origin and varieties of serpentine jade similar to Xiuyu jade. Therefore, when we identify jade articles belonging to this kind of jade since the Neolithic age, we must not easily determine the source of jade. During the period of 1977, among the Neolithic jades found by Nanjing Museum in Caoxie Mountain and Zhangling Mountain in Wuxian County, Jiangsu Province, 1 jade tube was identified as serpentine jade, which was not produced in Liaoning Province, and the jade material may be produced in Zhenjiang, Jiangsu Province. Fourth, the name of lantian jade lantian jade was first seen in History of Han Geography, and the beautiful jade was produced in Lantian Mountain in the north of Beijing (now the north of Xi 'an). Later, there were records of Lantian's jade production in ancient books such as Biography of consorts in the Later Han Dynasty, Zhang Heng's ode to Xijing, Guangya, Notes on Water Mirror and Yuanhe County Records. During the Wanli period of the Ming Dynasty, Song said in "Heavenly Creations": "The so-called Lantian is the alias of jade in Qingling (Kunlun Mountain), which was later mistaken for the Lantian of An. "Since then, it has caused disputes for later generations. Some people say that Lantian doesn't produce jade at all, and some people say that even if it produces jade, it may be laiyu (green jade with a color like a vegetable leaf). In recent years, Shaanxi geologists have discovered serpentine marble in Lantian, which is regarded as an ancient recorded lantian jade (1978165438+1October 23rd * *). This discovery not only attracted the attention of geologists looking for raw materials of Yuzhu, but also attracted the interest of archaeologists. 1982 geological museum, Ministry of Geology and Mineral Resources, exhibited the above-mentioned lantian jade rough stone. When this serpentine is strong, some parts have become jade like Xiuyu. From the appearance, jade has uneven tones such as yellow and light green, accompanied by light white marble. Although this kind of jade is not very beautiful, because Lantian is located near the ancient city of Xi 'an, the hardness of jade is about 4, and it is easy to process, so the ancients may use it as an ornament. There are two jade articles in the Han Dynasty that are very similar to lantian jade today. One is a large jade shop unearthed near Maoling, Emperor Wu of the Han Dynasty in Shaanxi Province, with its head embedded in the door of an ancient tomb. The other is Yu Pei of Han Dynasty in the Palace Museum. Judging from the jade quality and color of these two kinds of jade, many geologists think it is similar to lantian jade today. But whether it is really ancient lantian jade needs further testing. 5. Nanyangyu Nanyangyu is named after its production in Nanyang, Henan Province, and it is also called "dushan jade" because its mining area is in Dushan, Nanyang. Nanyang jade has bright color, fine texture, good luster and high hardness, which can be compared with jadeite. Germans once called it "Nanyang Emerald", and Soviet geologist Kivlinko once classified Nanyang jade as jadeite jade deposit. According to the research of Henan geologists in recent years, Nanyangyu is an altered plagioclase, which consists of zoisite, epidote, tremolite, sericite, biotite and sphene. Through microscopic identification, jade contains a variety of altered minerals, mainly zoisite, epidote and tremolite. Because jade contains all kinds of metal impurities, there are many colors of jade, mainly green, white and variegated, as well as purple, blue and yellow. The hardness of Nanyang jade is 6 ~ 6.5. With glass luster, most of them are opaque and a few are slightly transparent. The results of chemical analysis are as follows: silica 4 1 ~ 45%, alumina 30.7 1 ~ 34. 14%, magnesia 0.28 ~ 1.73%, potassium oxide 0.02 ~ 2.64% and iron oxide 0 ~ 0.8. The trace element analysis results of Nanyang jade are as follows: Cr 0.0 1 ~ 0.5%, Ni less than 0. 1%, v0.001~ 0./%,Mn 0.0 1 ~ 0.05%, Ti 0. According to written records, there is no doubt that Nanyang jade was mined in the Han Dynasty. Recent archaeological data pushed the exploitation of Nanyang jade before the late Shang Dynasty. 1952, Li Ji pointed out that there were 444 bladed stone tools in Yin Ruins, including 7 jade articles, all of which were made of Nanyang jade. The excavation report of No.5 Tomb of Yinxu in Anyang also pointed out that more than 700 jade articles were unearthed from Muhao Tomb of Yinxu, and more than 40 specimens were preliminarily identified. "Most of them are close to modern xiuyan jade in Liaoning, a few are close to Nanyang jade in Henan, and a few are similar to Hetian jade in Xinjiang." (Journal of Archaeology, No.2,1977)1At the gem lecture and academic exchange meeting in Chengdu, Sichuan Province in June, 1983, the Henan Geological Bureau said in a paper about Nanyang jade that a Nanyang jade shovel was unearthed in Huangshan, Nanyang County, and it was identified as a product of the late Neolithic Age, with a history of more than 6,000 years.