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AI mapping does not represent what happens in reality (photo source: Bing Image Creator) that gold always glows because it looks for places where there is light.

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Gold has been a symbol of wealth and power since ancient times: not only a rare and precious metal, but also dreams, desires and passions. In thousands of years of stories, the golden treasure has become the ultimate reward for those who seek adventure, glory and wealth. These people are willing to risk their lives to cross the ocean and explore unknown lands for gold.

The beauty and rarity of Jin make people yearn for and fascinate, and people also have all kinds of practical or unrealistic fantasies about Jin. People who want to lie flat sometimes say that such a joke comes from mockery: "I bury the gold in the earth, and the gold of a whole tree will grow next year, and I will be rich." Money doesn't grow on trees is often used in English to advise young people to gain wealth by their own efforts, rather than fantasize about achieving it overnight.

Admittedly, common sense tells us that "gold growing on trees" is just a joke. Gold buried in the soil does not take root, sprout and bear fruit like plants, and grow and propagate using air, light, water and soil.

But is there really no way for gold to grow in the soil?

Eucalyptus Gold Rush in 1893, during the "gold rush" in western Australia, two prospectors stumbled upon a gold mine during their trip. After the news spread, people from all over Australia quickly came. Later, the place gradually developed into a city-Kalgoorlie. To this day, Calgary is still famous for its mining industry. The next story takes place in the Freddo Gold Mine, a small gold mine 40 kilometers north of Calguri.

In Karguri in 1930, gold prospectors came here (photo: William Edward Fretwell-Public Domain), but now Freddo has no mining activity because it is economically uneconomical-the gold value it contains may not be able to support the cost of mining and other processes, so mining companies choose not to mine.

This also prevents the open woodland on the Freddo gold mine from being completely destroyed by mining. Although the deposit is located in a semi-arid area with an average annual precipitation of only 260mm and evapotranspiration of more than 2600 mm, the large eucalyptus trees (Eucalyptus) on it can still grow tall and tall, and many eucalyptus trees are more than 10m high. This is largely due to the deep and extensive roots of eucalyptus: according to research, the secondary absorbing roots of a kind of eucalyptus (Eucalyptus marginata) can even grow to a depth of 40m. Therefore, even in such a semi-arid environment, eucalyptus can still find underground water through its strong roots.

Eucalyptus trees growing above the Freddo gold mine take root deep underground in search of water, pass through clay and gravel in different weathering layers, and finally meet gold below 30m above the ground.

The journey of eucalyptus roots meeting gold. (photo Source: Lintern et al., 2013) although it meets the gold that humans have always dreamed of, for eucalyptus, the "gold" it pursues at this time is just a source of water, and metal gold can only be regarded as a bonus. Some of the gold elements in the gold mine will be dissolved in the surrounding water in the form of gold ions, and when the eucalyptus root arrives here to absorb water, it will take away the gold in the water. After the gold ion is absorbed by the root, it is like sitting on a sightseeing ladder and begins to travel up the vascular system of eucalyptus, from the ground to the ground, from the root to the trunk, to the canopy, along the branches into the eucalyptus leaves, and precipitate and reduce to elemental gold.

So is it possible for koalas to chew gold when they eat eucalyptus leaves? (photo: unsplash) the presence of gold in the leaves of a real tree is not new, but it was not until 2013, when Australian scientists studied eucalyptus trees at the Freddo gold mine, that it was first confirmed that plants can obtain gold from underground gold deposits and precipitate in the leaves. The study was published in the journal Nature.

The researchers collected the leaves of many eucalyptus trees growing in the Freddo gold mine and determined the gold content in the leaves. They found that the average gold content in the leaf sample was 46 ppb (parts per billion, 1/1000000000), with a maximum of 359 ppb;, compared with 16 ppb in the leaf sample of an eucalyptus tree 200m from the mine. Subsequently, they observed gold particles in eucalyptus leaves by X-ray fluorescence microprobe (X-ray Fluorescence Microprobe,XFM), the largest of which was 8 microns long.

Gold particles (red) in eucalyptus leaves in Freddo gold mine (photo source: Lintern et al., 2013) most of these gold particles are combined with calcium oxalate crystals in the leaves. Calcium oxalate plays an important role in the regulation of calcium transport in plants, but some studies have shown that calcium oxalate can separate the toxic metal components in plants from the important structures of plant cells. So the researchers speculate that gold may be potentially toxic to eucalyptus, which reduces the potentially harmful biochemical reactions of gold by combining calcium oxalate with gold.

To further prove that the gold came from underground gold deposits rather than being contaminated by gold in dust, the researchers planted eucalyptus in the laboratory with gold-rich soil. Finally, similar gold particles were observed in the eucalyptus leaves grown under the experimental conditions, and the gold in the leaves combined with calcium oxalate crystals in a similar way. Now, in a real sense, they buried the gold in the soil and planted trees with gold.

The gold particles in eucalyptus leaves planted in the laboratory with high "gold content" soil (photo e white arrow) (photo source: Lintern et al., 2013) fall "gold" is not heartless, turned into spring mud and back to the root 30m underground gold travels upward by transpiration, leaving traces along the way: some gold is left in the roots near the ground, some on tree trunks and branches Of course, the place with the highest gold density is the end of the journey-the leaves (although the gold density is the highest among the leaves, the total gold content in the trunk is actually the highest because the trunk is heavier). In addition to precipitating as gold particles in the leaves as above, the gold in the leaves may also be precipitated directly from the leaves (in another gold mine, the researchers found that in the secretion of eucalyptus leaves on the gold mine, the gold content is 20 times higher than that of eucalyptus leaves 800m away from the gold mine).

Comparison of gold density in different parts of eucalyptus and soil in Freddo Gold Mine (Photo: Lintern et al., 2013) Gold has completed an unusual journey from underground to eucalyptus, whether it ends up in roots, trunks, leaves or other parts of eucalyptus. Of course, the end of one journey may be the beginning of another, and some of the gold left on eucalyptus trees soon opens a new story.

The leaves will leave the tree one day, and so will the gold hidden in the tree. Leaves will fall, branches and bark will fall, roots will fall off, and tree trunks will rot. At this time, the gold in the tree will also return to the soil with them. As the organic part is degraded, gold and other inorganic members also begin to find their own homes in the soil. For gold, some are left in the calcareous conglomerate in the soil, some are dissolved in the water in the soil, are reabsorbed by eucalyptus roots, and then repeat the previous journey, and so on. In this way, the flow balance of the gold element was achieved.

Photo Source: can Bing Image Creator make money from it? Sure! Although this is literally "gold growing on the tree", if your idea is to collect the gold and sell it, it is unlikely to make money, because the cost of extracting and enriching the gold is mostly higher than the total value of the gold.

Although there is not so much gold on the ground, there is much underground. By detecting whether there are gold particles in the leaves, we can infer whether there is gold under the tree, which may save a lot of exploration costs. In 2019, a mining company found gold in South Australia through leaves. According to New Scientist, the 6-meter-long vein contains 3.4g of gold per ton.

Gold always glows, and even if it is buried 34 meters underground, it may come to the ground along the roots of the tree. Just like the star next to the official account of Global Science, it can shine when you light it up!

The cover image is generated by AI, source: Bing Image Creator

Reference link:

Https://www.nature.com/articles/ncomms3614#ref-CR30

Https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=cb5a17a0c8a28ff5752edc3ecdb275cca51742ae

Https://pubmed.ncbi.nlm.nih.gov/15887364/

Https://www.elsevier.com/books/biogeochemistry-in-mineral-exploration/dunn/978-0-444-53074-5

Https://www.newscientist.com/article/2213033-a-company-has-used-trees-to-find-gold-deep-underground-in-australia/

Https://www.iflscience.com/gold-literally-grows-on-trees-in-australia-68140

Https://www.zmescience.com/research/gold-growing-on-trees-offers-a-new-prospecting-tool/

Https://www.nationalgeographic.com/science/article/131022-gold-eucalyptus-leaves-mining-geology-science

Https://www.livescience.com/28676-plants-grow-gold.html

This article comes from the official account of Wechat: global Science (ID:huanqiukexue)

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