Where Does Gold Come From?
It’s a well-known fact that gold is one of the rarest metals on Earth. Yet, have you ever wondered why and from where did it come? – this is a pretty big question. The scientific world has a variety of theories. While I use some scientific terminology in this article, this article will include definitions at the end.
Let’s quickly review just how little gold has been extracted from the planet so far. As of 2019, 197,576 tonnes of gold have been mined. For a visual representation of this amount, that’s a cube with each side approximately 21.7 meters long. Picture a square building seven stories tall and equally as wide. That’s it. That’s everything.
Currently, there are three schools of thought as to how gold came to exist in the universe.
- The first states that gold comes from supernova nucleosynthesis. Simply put, this is when chemical elements experience nucleosynthesis as a direct result of being in a sun that has entered a supernova explosion.
- The second supposition is that the collision of neutron stars creates it.
- The third is that it already existed in the dust that formed the solar system.
It is also possible that gold on Earth originated from a combination of all these events.
It is posited that most gold formed in the initial 20 minutes of the big bang that kick-started the universe. Neutron star collisions still produce smaller amounts of gold, but these events are not relevant to the amount of gold on Earth.
The theory is that when the Earth was forming and still in a molten state, existing gold sank into the planet’s core and that gold found in the crust and mantle arrived on Earth after it had cooled off sufficiently to become solid. Asteroid strikes that happened about 4 billion years ago during an era known as the Late Heavy Bombardment delivered the gold to the Earth’s mantle and crust.
One asteroid strike, in particular, is thought to be responsible for approximately 22% of the gold mined to date. This strike formed the 300km diameter Vredefort Crater in South Africa about 2.02 billion years ago. While this strike is not thought to have brought any gold with it, the force of the strike severely altered the landscape, exposing deep-buried gold-laden rocks.
The scientific theory posits that remaining mined gold has been present since Earth’s inception: The gold has risen from the mantle and deposited on the surface over the ages and through various thermal and volcanic events.
Gold continues to be mined all over the world to this day. It is often a by-product of either copper or silver mining, but there are many gold-specific mines. As of 2017, the largest national producer of gold was China, with an annual production of 440 tonnes.
Various theories about the exact origins of gold involve some degree of speculation, and this is understandable as these ideas address events as far back as the big bang itself. With the advent of more powerful AI, computer modelling analyzing data becomes more accessible and more of an exact science. Scientists will undoubtedly reveal more certain explanations to us in time. One certainty is we have very little of the metal on our planet.
Nucleosynthesis – The process is responsible for creating new atomic nuclei from pre-existing nucleons and nuclei.
Neutron star – The collapsed core of a formal supergiant star with a mass of 10 -25 times its previous incarnation.
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