Dushan jade identification features:
The difference between Dushan jade and similar jade. The same piece of Dushan jade can appear 2~3 kinds or more colors at the same time, and the color is bright. The emerald green dun jade looks like jade. If you look closely, the green jade has a granular structure or a dissolution structure. The main minerals are plagioclase and emerald green chrome mica with good transparency. Jade and nephrite are interwoven in a fiber.
Causes of production: produced in the altered plagioclase, due to the basic plagioclase or gabbro at low temperature, formed by the late magmatic latent hot aqueous solution along the structural fissures, alteration and other effects;
Famous place of origin: The world famous place is Dushan, Nanyang City, Henan Province, China.
Name source: Named after Dushan, a suburb of Nanyang City, Henan Province, China, it is also known as “Nanyang Yu†and “Jiyuâ€. Nanyang is known as the "hometown of jade";
::crystal morphology
Fine-grained crystals; fine particles, particle size less than 0.05mm, cryptocrystalline, fine texture, hard and compact;
::Physical properties
Hardness: 6.0-6.5
Specific gravity: 2.73-3.18g/cm3
Color: Dushan jade is a multi-color jade system composed of 2~3 kinds of colors. Common colors are white, green, purple, yellow, red, black, etc.
Transparency: transparent to translucent
Gloss: glass or grease gloss
Under the microscope: there are black spots, the color is not bright, and a variety of mineral inclusions can be seen.
As early as 6,000 years ago, the ancients had exploited Dushan jade, and there were many products of Dushan jade in the jade unearthed from the Yinzheng Tomb of Anyang. In the Western Han Dynasty, Dushan was called "Yushan."
Due to its bright color and good transparency, Dushan jade ranks among the “Four Famous Jade†in China. The emerald green variety of high-grade unique jade is similar to Burmese jade, so it has the reputation of “Nanyang Jadeâ€. Generally, jade is mainly used to sculpt various furnishings and accessories such as bracelets, rings and necklaces.
Dushan jade is best in color, high transparency, fine texture and no impurity cracks. Among them, the value of hibiscus stone, permeable white jade and green jade is higher. In addition, the use of jade blocks of different colors to imitate the natural production of the jade jade carving has been well received.
According to the research of Henan geological workers in recent years, it is found that Nanyang jade is an altered plagioclase, composed of minerals other than plagioclase, as well as zoisite, epidote, tremolite, sericite, black. Mica and meteorites. After microscopic identification, jade contains a variety of altered minerals, and the alteration effect is dominated by é» çŸ³åŒ– petrochemical, chlorite petrochemical and tremolite. Because jade contains various metal impurities (electron ions), the color of jade has a variety of colors, mainly green, white, and variegated, as well as purple, blue, yellow and other colors.
chemical composition
Nanyang jade hardness 6 ~ 6.5. It has a glass luster, most opaque, and a few are slightly transparent. The results of chemical analysis are: silica 41 to 45%, alumina 30.71 to 34.14%, magnesium oxide 0.28 to 1.73%, potassium oxide 0.02 to 2.64%, ferric oxide 0 to 0.8%, ferrous oxide 0.27 to 0.88 %, manganese oxide 0.02 to 0.1%, chromium oxide 0.01 to 0.34%, crystal water 0.23 to 0.74%, and carbon dioxide 0.06 to 0.52%. The trace element analysis results of Nanyang jade are: 0.01-0.5% of chromium, less than 0.1% of nickel, 0.001-0.1% of vanadium, 0.01-0.05% of manganese, and 0.001-0.5% of titanium.
Mining history
According to written records, Nanyang jade has been mined in the Han Dynasty without a doubt. Recently, the archaeologically unearthed materials pushed the mining of Nanyangyu to the late Shang Dynasty. In 1952, Li Ji pointed out in the "Swords of the Stones in the Yin Ruins" that there were 444 pieces of stone tools in the Yin Ruins, including seven pieces of jade, and the materials of the seven pieces of jade were all Nanyang jade. The "Excavation Report of the No. 5 Tomb of Yin Ruins in Anyang" also pointed out that more than 700 pieces of jade articles unearthed in the Yinxu Women's Tomb, including more than forty pieces of specimens, were initially identified. "Most of them are close to modern Liaoning Xiuyan jade, a few Henan Nanyang jade is close, very similar to Xinjiang and Yu (Jian) ​​jade." ("Archaeologic Journal" 1977, 2nd issue) and October 1983 in Chengdu, Sichuan "Gemstone Lecture and Academic Exchange", Henan Province The Geological Bureau read a paper about Nanyang Yu that a Nanyang jade shovel was unearthed in Huangshan, Nanyang County. It was identified as a product of the late Neolithic period. It has a history of more than 6,000 years and it is known that Nanyang Yuzao It was adopted in the late Neolithic period.
Duyu is one of the four famous jade in China. The mining area of ​​Duyu is located in the “Dushan†in the northern suburbs of Nanyang City, Henan Province, also known as “Nanyangyuâ€. The unique jade is plagioclase jade, with fine texture and grease or glass luster. It has good polishing performance, transparent and more than three colors to form multi-color jade. The color is bright and the hardness is more than 6.5. The main varieties are: white jade, green jade, green white jade, purple jade, topaz, hibiscus ruby, ink jade and variegated jade. The unique jade mining has a long history. The Neolithic Longshan culture jade axe unearthed from Shenmu Dendrobium in Shaanxi Province and the Yuan Dynasty “Yushan Dayuhaiâ€, which is now displayed in the Beijing Beihai Park Mission City, are all unique. The mining of the unique jade has been quite large in the Han Dynasty. Up to now, there are more than one thousand ancient jade mines in the Dushan of Nanyang. It can be seen that the mining of the unique jade has a long history, the scale is flourishing, and the variety is abundant.
Identification method
Dushan jade has a special structure and color change, which makes it easier to distinguish it from other jade. However, certain color varieties are sometimes similar to other jade.
The translucent blue-green Dushan jade is similar in appearance to the high-quality jadeite, but the jadeite fiber interweaving structure is significantly different from the monolithic structure of Dushan jade. It is easy to distinguish the two by refractive index value and density value test. Moreover, the color of this unique jade is caused by chrome-containing mica, which turns red under the Charles filter. In addition, the green color of the Dushan jade is blue, often with dark spots of dark minerals. These characteristics are also distinct from similar jadeite.
Bai Duyu is confused with quartz jade in similar appearance and white jade in nephrite. The structure of white jade is felt-like structure, very delicate, and the gloss is generally glass-grease luster. These are easily distinguished from Dushan jade, quartz. Although jade is also a granular structure, its refractive index and specific gravity are significantly lower than that of Dushan jade, so it is also very well distinguished.
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