Shulou(Shulou.com)11/24 Report--

This time, let's take a look at the deep and distant stone green in only this Green.

Qianli Jiangshan map (excerpt) Shiqing, also known as Baiqing, Biqing, fish eye green, flat green, Daqing, taken from azurite, can also be used as a kind of traditional Chinese medicine, mainly composed of basic copper carbonate Cu3 (CO3) 2 (OH) 2. The essence of Pinghui in the Ming Dynasty also recorded the processing method of Shi Qing: "first ramming, but also flying very fine with water, waiting for drying, and then studying and using it." The ore is mashed, filtered according to the size of the particles by water flying, air-dried, and grinded open when in use. [1] Shi Qing can be divided into Touqing, Erqing, Sanqing and Siqing. In Chinese painting green landscape, stone green is the main color, because the coverage of stone green is strong, it can be covered layer by layer when painting, so painters like to use mineral color stone blue to coagulate the texture of the mountain body when painting landscape. [2]

How did the beautiful azurite come into being?

Azurite (stone green) and malachite (stone green) are closely symbiotic, which can be called brothers in a pair of underpants. Like malachite, azurite occurs in the oxidation zone of copper deposits and is a secondary product of the oxidation of copper-bearing sulfides. However, when the temperature increases, azurite is easily transformed into malachite. When the season is dry and under the condition of sufficient amount of carbonic acid, malachite (stone green) can be transformed into azurite (azurite), so the distribution of azurite is not as wide as malachite.

The association of azurite and copper ore can be used as a sign of searching for primary copper ore, so the mineral land of azurite is highly coincident with the copper deposit, which is mainly located in Yangchun, Guangdong, Hubei Daye and northwest Jiangxi, and the top pillar of the three is Hubei Daye Copper Mine.

If you want to say the producing area of the copper deposit in Daye, Hubei Province, it must be impossible to bypass the "Copper Green Mountain". Tonglushan Orefield is located in southeastern Hubei, one of the seven ore concentration areas in the middle and lower reaches of the Yangtze River metallogenic belt, where there are rich copper and iron deposits and symbiosis with gold, silver, drilling and other non-ferrous metals. The area of Tonglushan ancient mining area is about two kilometers from north to south and one kilometer from east to west (figure 1). There are also remains of ancient smelting furnaces near the ancient mine, which are preserved because they are buried by slag. The surface of many sites is covered with more than one meter thick ancient slag, the total amount is estimated to be about 400000 tons, and this is only the slag discarded after copper smelting, based on 400000 tons of slag, it is estimated that the red copper extracted in ancient times should be 40,000 tons! [3]

Tonglushan site in Daye, Hubei Province

In order to solve the genesis of azurite in Hubei area, the map of Tonglushan deposit needs to solve the genesis of copper deposit in Hubei area, so the problem comes again, how did Tonglushan copper deposit come into being?

According to geologists, the copper deposit in Tonglushan comes from the magmatic activity of plate tectonics. In terms of the location of the mining area, Tonglu Mountain in Daye, Hubei Province is located in the southeastern Hubei ore concentration area in the western part of the metallogenic belt in the middle and lower reaches of the Yangtze River, where high-grade copper and iron are the main dominant minerals, including many large metal fields with complete metallogenic types.

From the geotectonic location, the ore concentration area in southeastern Hubei is located on the northern margin of the Yangtze platform, the western part of the lower Yangtze depression belt (platform fold belt), the Dabie orogenic belt in the north and the Mufushan metamorphic core complex belt in the south. This area is located in the continental margin of the Paleo-Yangtze region in the Paleozoic era, in the eastern part of the Paleo-Yangtze plate in the Paleozoic-early Mesozoic era, and in the tectonic active belt within the Eurasian continent in the late Mesozoic-Cenozoic. From the beginning of the small size of this block, it is basically either in the tectonic zone or wrapped in a circle by the tectonic belt, which is clearly arranged by plate tectonic activities.

According to the scientific analysis of regional stratigraphy in Tonglushan area, the location map of Yangzi block shows that the main source of ore-forming elements in Tonglushan may be the magmatic source of deep crust or upper slow, that is to say, magmatic rocks are the main carriers of ore-forming materials.

So how did these copper-rich ore liquids form Tonglushan? Some readers may say that it is reasonable but not accurate to say that it entered with the fault zone caused by tectonism.

Geologists have studied the ore-forming channels of the Tonglushan ore field and found that there is only a network connection between the reservoir and the rocks. In other words, the ore-forming fluid enters the ore field through small cracks or intergranular gaps in the rock. After the magmatic period, the first high-temperature supercritical fluid is produced, and the characteristics of supercritical fluid make it extract more ore-forming materials, which are the pioneers of the fluid. After heating the surrounding material, the hot magma begins to cool slowly. We all know that the heat expands and shrinks, and when the magma cools, the volume begins to decrease. At the same time, after the magmatic rock is consolidated, on the contact surface between the magmatic rock and the carbonate rock, there is a suction to converge the fluid into the contact surface due to cold shrinkage. To put it simply, like cupping, the gas in the cupping produces a suction on the skin when it cools, but now it becomes the contact surface between the cooling lava and fluid and its surroundings.

After the critical transformation, the supercritical fluid is transformed into a high temperature fluid, the pressure in the cold shrinking low pressure area decreases, and the suction provides the power for the fluid convergence again. With the decrease of temperature and the gradual increase of suction, these fluids converge, and a large number of residual fluids formed after critical conversion are mixed with fluids from different directions, resulting in the precipitation of gold dominated by copper.

The consolidation of magma is gradual, and the fluid converging to the contact surface gradually extends to the interior of the rock mass with the consolidation of the rock mass, thus forming a connected channel from the contact to the rock mass. These channels form a network horizontally and longitudinally, and they may be connected with some fissures to form larger channels, or they may just communicate between particles directly to the contact surface. When the magma cools gradually, the ore-bearing hydrothermal solution continues to converge from the outside to the contact zone, forming a fluid convergence channel. Therefore, the ore transport channel is an intergranular fracture or small pore, rather than a large-scale fault structure, which promotes the enrichment of ore-bearing hydrothermal solution in Tonglushan.

The thermal energy of magma not only comes into contact with carbonate rocks, but also heats the original rocks to cause thermal metamorphism, which not only empties the fluid in it, but also fills up most of the cracks, forming a relatively closed and hard rock "cap". The relatively stable environment and the relatively closed contact surface provide conditions for ore-bearing fluid convergence, traps, long-term residence and even diagenesis and mineralization. [4]

For Tonglu Mountain, magmatic activity is its "mother".

Azurite is a kind of water-rich alkaline copper carbonate produced by the interaction between aqueous solution containing copper in rock and limestone, oxidation and alteration. The chemical composition of malachite is Cu2 (OH) 2CO3, which theoretically contains CuO 71.95% CuO 19.90% CuO 8.15%; azurite Cu3 (CO3) 2 (OH) 2, which theoretically contains CuO 69.24% CO _ 2 25.53% H _ 2O 5.23%. [5] [6]

When the oxide layer of copper ore is in an underground closed, dry, carbon dioxide-rich environment, malachite will be converted into azurite; if the above conditions are not met, azurite will be transformed into malachite. This reversible symbiotic relationship is very strange and rare in the natural mineral population. Sometimes, in the ore bed rock, the two single crystals symbiosis together, creating a beautiful crystal cluster of half azurite crystal and the other half malachite crystal. [7]

The green of malachite and the blue of azurite are the color of the mineral itself, which is the result of the specific absorption and reflection of specific wavelength light by chromogenic elements and mineral crystal structure. It is precisely under the miraculous craftsmanship of nature that Wang Ximeng, through the creation of heaven and earth, has drawn a picture of thick and green landscapes with thousands of years of mineral pigments, laying a milestone in the development of green landscapes!

reference

[1] Baidu encyclopedia Shi Qing. Baidu Encyclopedia (baidu.com)

[2] Art pioneer. A brief talk on the mineral search for stone blue in traditional Chinese painting. 2018-09-20.

Xia Yi, Yin Weizhang. Tonglushan ancient copper deposit, Hubei [J]. The Journal of Archaeology 1982 (01).

[4] Zhang Zongbao. Study on metallogenic system of Tonglushan Orefield in Hubei Province [D]. China University of Geosciences (Beijing). 2011 07 16.

[5] Baidu encyclopedia azurite. Baidu Encyclopedia (baidu.com)

[6] malachite in Baidu encyclopedia. Baidu Encyclopedia (baidu.com)

[7] Zhao Xiaochen. Twin sisters-malachite and azurite [J]. Encyclopedic knowledge. 2011 (14).

This article is from the official account of Wechat: stone popular Science Studio (ID:Dr__Stone). Author: Bian Zhou

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