China's gold mines are mainly in Inner Mongolia, Shandong, Xinjiang, Henan and other places, and the annual output is actually only two or three hundred tons. In order to reserve gold, China has set up a special gold survey force, which is found in some of the main mountain exploration gold mines in our country, and the most important purpose of this is to reserve gold to cope with changes in the currency market, which is also of great significance to the country's economic security.
Recently, Henan geological prospectors in the Funiu Mountain gold vein found a very large gold mine, located in the territory of Tongbai County in Nanyang, Henan, the estimated reserves are about 31.55 tons, by the end of the year may increase to about 50 tons, and the quality of this gold mine is quite good, about 5 grams per ton of ore, at a depth of more than 1,000 meters underground, the local is still exploring the scope of the gold vein by drilling the core and other ways. More than 2 grams per ton on the ground has mining value, and it is conceivable that the enrichment of this gold mine is still quite good, and gold often has other half-raw metals.
31.55 tons of gold, it does not look like a lot, but compared with China's annual output, it is equivalent to about 1/10, and because the gold mine is only a few grams of gold, so don't look at only 31.55 tons of gold, all mined out but it takes a long time, the annual output of a few tons is quite good. The classification of gold mines in China is carried out according to reserves: general rock gold ore < 5 tons is small, 5 tons -20 tons is medium-sized, > 20 tons is large. Placer gold ore < 2 tons is small, 2 tons -8 tons is medium sized, and more than 8 tons is large.
This explains why more than 30 tons of reserves are called extraordinarily large gold mines. The gap between this kind of gold mine and the world-class large gold mine is still quite large, and the highest annual output of the only world-class mega gold mine in China is about 16 tons, and its annual output is still decreasing as it is mined. The world's top ten world-class mega gold mines have an annual output of more than 18 tons. The storage and distribution of gold on the surface of the earth is quite uneven, and the degree of enrichment is generally not high, which makes gold a heavy metal since ancient times.
According to scientists' estimates, there are about 60 trillion tons of gold on the earth, and everyone in the world can't share thousands of tons, but why is the stock on the surface so low? In fact, the reason many people know, that is, gold is generally buried deeper. This is due to the properties of gold itself, as a heavy metal, the density of gold is relatively high, in the early days of the formation of the earth, the earth due to a large amount of material collision lithosphere in a molten state, gold density naturally settles into the earth's interior.
In the 1980s, the Soviet Union carried out the Earth Telescope program, which wanted to drill through the earth's crust to study the discontinuous interface between the mantle and the earth's crust, and eventually formed a Kola ultra-deep drilling well with a depth of more than 12,000 meters, and when drilled to about 9,000 meters, the reserves of ore gold per ton in the cores taken out were as high as 80 grams, which was much higher than the concentration of gold on the surface. But such ores are hidden too deep to be excavated to build large gold mines, and the deepest gold mine is currently located in South Africa, with mining depths of more than 4 kilometers.
Gold is mostly in the interior of the earth, and gold on the surface needs to be brought to the surface through volcanic eruptions and plate movements. According to scientific measurements and inferences, about 2.6 billion years ago in the Primeval, volcanic eruptions brought a large amount of gold from the core along the fissure to the mantle and crust, and then through marine sedimentation and regional metamorphism, the first source of gold was formed. There are many reserves of gold throughout the earth, but the diameter of the earth is close to 13,000 kilometers, and 60 trillion tons of gold are quite scattered in the earth's interior.
This is also why it is easy to form gold mines in places where there have been volcanic eruptions or geological reconstructions, and gold mines often have many other relatively rare metals, such as copper, nickel, cobalt, antimony, lead and so on. Pure natural gold is rare, which often contains a certain amount of Ag, forming the Au-Ag series of minerals. These metals are also squeezed out of the earth's interior by huge pressures and trapped in the lithosphere that has cooled and solidified with phenomena such as volcanic eruptions.
Dog head gold with a high natural gold content is also formed in nature. In 1983, a huge gold nugget was found in the Brazilian state of Pará, which weighed 60.82 kilograms, removing impurities, and the content of pure gold was about 52 kilograms. In the place where the dog head gold has been found again, the probability of finding it again is also higher, in China's Sichuan Province Baiyu County Konglonggou, there is a ravine rich in dog head gold, in 1987 and found a large gold nugget weighing 4800.8g and 6136.15g, successively refreshing the weight record of finding dog head gold in China since the founding of the People's Republic of China, which is called a "national treasure".
Due to the different scales of geological activities in the world, there is a great difference in the reserves of precious metals, don't look at the small place in Japan, but once it was rich in silver, there were some fairly high-quality gold mines, the average grade of lingyi gold in southern Kyushu is even as high as 33 g / ton, the highest grade is thousands to tens of thousands of g / ton! The gold sources that come to the surface are constantly relocated due to rain erosion, wind and sun, and geological changes, which once again causes the distribution of gold.