我认为Jaxon回答描述了黄金的情况下形成和发现(矿脉存款)[1]。但在矿脉(自然金)[2]可以受到风化暴露时,向环境释放的黄金薄片,谷物和掘金。这个黄金是那么受侵蚀和沉积过程。黄金的密度比大多数矿物往往集中在沉积过程(砂矿矿床)[3],黄金在哪里集中由重力。密集的黄金很快落定的水柱,和轻矿物把挑出来了。这些积累的黄金可以经济开采使用[砂矿开采][4][淘金][5]等技术。(威特沃特斯兰德盆地)[6]在南非是一个重要的palaeo-placer存款几乎50%的黄金开采获得。冲积砂矿形成致密颗粒的沉积速度仍低于水的地方,需要进一步运输。金砂矿矿床的典型位置的内部弯曲河流和小溪,洞里钻,在边坡的破坏的基础流或一个陡坡,瀑布或其他障碍。地球上绝大多数的黄金和其他重金属被冻结在地球的核心,是一个密集的材料大部分的黄金被认为已经降到地球为核心形成的中心。 Though there is 1000 times more gold in the Earth's silicate mantle than would be expected. Evidence from tungsten isotope studies indicates that most of the gold in the mantle and crust (which we can access) is derived from gold which arrived during the [Late Heavy Bombardment][7] some 3.9 billion years ago.([BBC Article 1][8]) Which has been called the Late Veneer Hypothesis.([BBC Article 2][9]) Future mining of asteroids for gold and other metals has been proposed,([Reuters Article][10]) with estimates that there are up to 20,000 million tonnes of gold in the near-Earth asteroid Eros, with an estimated value of $1,000 billion (1999).([BBC Article 3][11]) [1]: https://en.wikipedia.org/wiki/Lode [2]: https://en.wikipedia.org/wiki/Native_metal [3]: https://en.wikipedia.org/wiki/Placer_deposit [4]: https://en.wikipedia.org/wiki/Placer_mining [5]: https://en.wikipedia.org/wiki/Gold_panning [6]: https://en.wikipedia.org/wiki/Witwatersrand_basin [7]: https://en.wikipedia.org/wiki/Late_Heavy_Bombardment [8]: http://www.bbc.co.uk/news/science-environment-14827624 [9]: http://www.bbc.co.uk/news/magazine-22904141 [10]: http://uk.reuters.com/article/2013/11/21/us-space-mining-asteroids-idUKBRE9AK0JF20131121 [11]: http://news.bbc.co.uk/1/hi/sci/tech/401227.stm
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