How is Gold Formed?
Gold, represented by the symbol “Au” on the periodic table, is arguably the most popular precious metal. It may not be the most expensive rare metal element out there, but it’s undoubtedly the most coveted.
The metal’s appeal can be attributed to its attractive appearance and varied applications. Its strengths have been corrosion resistance, malleability, ductility, electrical conductivity, and, of course, good looks. Gold is not running out of favor with humans anytime soon.
Due to the ubiquitous nature of gold and its popularity, most people know how valuable gold is. But if you ask them how gold is formed or where it stems from, most will pause, blink, and find themselves stunned. The standard response is likely to be gold mining, but that isn’t the answer to the question. Mining activities help bring out already formed gold. They do not help create or make gold, however.
So, how is gold formed? Since we’ve been using gold for centuries, it’s only fair that we also get familiar with the genesis of the material. In this article, we’ll deep-dive into the topic to know just that. Don’t worry. We’ll keep things as non-technical or layperson-friendly as possible. We want you to learn.
So, please continue reading.
Table of Contents
How is Gold Formed?
Gold’s origin can be traced back billion years ago. It’s believed that the neutron star collisions and supernovae formed around the time of the birth of planet Earth are responsible for all the gold found on our planet. In other words, the atomic processes of fission, fusion, radioactive decay, gamma-ray burst, etc., resulted in the creation of gold.
The gold particles resulting from those nuclear reactions ended in Earth’s crust when Earth was still forming. Iron and other heavy elements and base metals, too, headed straight to the Earth’s core. Asteroids and meteor strikes later bombarded Earth over a period, which shook our planet’s deeper layers, pushing gold and other heavy metals further into the mantle and core.
The phenomenon mentioned above that took place millions of years ago is why gold is mined and not dug up or excavated. A lot of accessible gold in the form of placer deposits have existed in the past. Those were due to the complementing natural processes after the molten rock ores came near the Earth’s surface.
Read more: How Much Gold There is in the World
Why Can Humans Not Make Gold?
If you wondered whether you could replicate the nuclear processes mentioned above in a laboratory, the straight and simple answer would be “no”. No chemistry or alchemy can produce gold like a nuclear fusion, as chemical reactions do not alter the proton makeup of gold atoms or any other element.
Protons lend to an atom’s mass, and their sheer number ascertains the identity of a given element. Gold is gold because it has 79 protons—79 being the atomic number of gold. If the count were 80, it would have been mercury, and the atomic number would have changed too. And if the proton count dropped by one to 78, then you’re dealing with platinum, a completely different metal.
Despite zero possibilities, failed attempts in the past by alchemists to make gold out of the chemical element lead have been made. Those efforts failed because the chemical reactions carried out could only transfer electrons. When an element’s electron numbers (atom level) change, it becomes an ion.
How is Gold Deposited?
Gold is generally found in an impure or alloyed state, in alluvial deposits, rock ores, etc. Gold nuggets and flakes found in water bodies are usually the purest forms of a gold deposit. The naturally occurring electrum is a gold and silver alloy.
Gold usually occurs in the lodes (veins) of fractured rocks. These lode deposits form when heated fluids flow via gold-bearing rocks, collecting gold and depositing them into new areas in the crust. The chemical disparities in the rocks and the fluids and the physical changes in the stones create several varied kinds of lode deposits.
Chemical interactions between sedimentary/igneous rocks and the high-temperature fluids create tiny gold particle deposits in the crystallized and solidified molten rock.
Tectonic Activities Disposition Gold
Earthquakes play an essential role in how and where gold gets deposited. A quake can easily crack up a fluid-infused rock, allowing the gold concentrations within it to percolate out. Most of the world’s gold deposits are believed to be formed courtesy of this very natural phenomenon.
And you do not need a significant earthquake for the rocks to crack and allow the tiny gold deposits within to move out. Even an earthquake with a score of 2 on the Richter scale can facilitate the process. Generally, humans do not feel tremors with a magnitude of less than 3. A lot of the mineralization and deposition, therefore, takes place undercover.
For the gold deposition to reach significant levels, a series of earthquakes (noticeable or not) must occur in a particular region over a period. Most of the dry areas of Earth have been explored for gold, which is why digging into the deeper portions of the Earth’s crust has become essential.
Kindly note an earthquake-prone region is no indication the place has gold deposits. If gold exists in the area naturally, a trembler will only cause a shift in its positioning.
Volcanic Systems Transport Gold
Gold deposits have continually formed in active volcanic regions. The yellow metal is, in fact, frequently associated with volcanic systems (not volcanoes). A volcano doesn’t create gold, but it facilitates its transportation, just like an earthquake.
A volcano is instrumental in spreading open the Earth’s crust. The various minerals (including gold) that are safely put in the viscous liquid flow out to meet cold ocean waters, as a result, and coagulate. These harden over time to form gold deposits.
How does gold occur inside a volcano in the first place? Intense heat emanating from the magma underneath a volcano could heat the mineral-rich groundwater, producing boiling acidic springs. Those water springs dissolve the neighboring gold-embedded rocks.
Because gold’s a dense material, it remains in the magma reservoir, falling to the bottom, while other particles move around a lot more freely. Over a period, large concentrations of the yellow metal accumulate in the area. As the magma levels go up or reach the Earth’s surface, it erupts and turns into lava, containing some gold from the underground reservoir.
The gold brought to the fore gets transported to distant regions, usually several miles away. The rocks surrounding an active volcano usually disintegrate under the heat of the molten lava, making the travel smoother or obstacle-free for the molten substance. The gold present in the lava may deposit in the worn-down rocks.
The gold flakes ultimately get released and move toward the beds of streams. The precious metal is then recovered with placer mining techniques.
Erosion Plays Its Part Too
Erosion causes gold particles to separate from gold-bearing rocks and enter water bodies. Since gold is denser than water, like pretty much every other metal, the precious metal sinks in water and is, therefore, found in stream beds (the bottom of a river or stream), oceans, etc.
Geographies Likely to Have Higher Gold Deposits
The above information should have given you a fair idea of the regions humans are likely to find gold or that not all parts of the Earth’s crust hold rare elements in them.
In regions where molten rock brings gold and other precious metals to the ground from within the mantle, the crust holds multiple times the gold the Earth’s crust could contain elsewhere.
However, these gold-bearing regions aren’t ideal for commercial mining since the process could leave behind massive open pits, creating a large amount of waste. Not to mention, the gold extracted may not be worth the time, money, and resources spent.
Other areas with possibly higher gold concentrations are major igneous provinces or regions with extensive igneous rock accumulations. Gold occurs quite commonly in those rocks, with a vast majority of those stones likely to have thin gold grains. Gold accumulates in igneous rocks due to erosion. Mantle hotspots are usually made of igneous rocks and, therefore, have greater concentrations of gold besides other rare metals.
A Lot More Gold is Out of Reach
Kindly note that all the gold mining has been from the crust to date. Also, the planet’s core and mantle, which are thousands of miles deeper, are likely to hold more gold than the crust. The deeper the search, the greater would be the find. How much gold the two more deep Earth layers contain is unknown.
On the other hand, ocean floors are the second most likely to harbor gold. They, however, aren’t your typical gold mining sites because the mining industry hasn’t come up with an economically feasible method to extract all that gold yet.
Read more: A Comparison Between Brass and Gold
Gold mining is a highly capital-intensive, time-consuming process. And the amount of gold unearthed to date for all that effort is negligible.
That’s because gold is a rare metal that isn’t readily found, and ascertaining its exact locations can be tricky. The rareness can be attributed to how gold forms (or has already formed) in nature, and that synthesized gold is borderline impossible.
It’s safe to assume the curiosity of humans to learn how gold forms stems from the deep desire to have more of the precious metal or understand the science so that it could be produced inside laboratories. For human-made gold to become a reality, considering all the science gathered until now, would take decades at the least.
Until then, we may have to keep learning, hoping for a breakthrough.