May 2024


May 2024

How is Gold Formed and Where Does it Come From?

By StoneX Bullion

Gold has been associated with wealth, power, and beauty for centuries across human civilization - but how exactly was this precious metal formed and where does it come from?

In this article, we look at gold’s origins in the cosmos, the geological processes that helped form gold on Earth, and where gold is found. We also look at when gold was discovered, potential sources of gold in the future, and whether or not gold can be synthesized.

Where does gold come from?

Gold's origin story stretches back to the early days of the solar system. To understand where it comes from, we have to go back before our planet was even formed…

Gold's story begins in the stars, with supernova explosions and neutron star collisions. These cataclysmic cosmic events involve explosions so extreme that they create heavy metals, including gold, and blast them into space as part of cosmic dust. Over billions of years, this dust, enriched with gold particles and other elements, formed new stars and planetary systems, including our solar system.

When the Earth formed about 4.6 billion years ago, the planet differentiated into layers. During this period, gold and other heavy elements sank towards the Earth’s core. Not all of it made it there, however, and some remained on the Earth’s mantle and crust, waiting to be discovered.

While some of the Earth’s gold has been here since our planet’s formation, a significant portion of it is thought to have arrived via asteroids. This theory explains why so much gold is found near the Earth’s surface. Either way, gold has traveled across the depths of space and time to arrive on our planet. But its journey doesn’t end there - several geological processes are required to turn gold into the precious metal we treasure today.

Read more: Why Buy Gold? Reasons to Invest in Physical Gold Bullion

How is gold made?

Cosmic events and asteroids brought gold atoms to Earth, but millions of years of geological processes transformed these particles into gold deposits. These processes include hydrothermal activities, magmatic processes, and various geological conditions deep within the Earth’s crust. Let’s look at how gold is made.

Hydrothermal activities

One of the main ways gold is formed is through hydrothermal processes. Deep within the Earth, mineral-rich water can become heated by surrounding rock and magma. This fluid begins to move through fractures and porous rocks, transporting gold and other minerals. When the hydrothermal fluids cool, the gold dissolves and leaks out of the solution to form gold-bearing veins, often found within quartz or other rocks.

Magmatic processes

Another way gold is formed is through magmatic processes. Gold is often found in small amounts within the Earth’s mantle. When magma forms through the partial melting of mantle rocks, it can carry gold and other dissolved metals. As the magma rises towards the surface, it brings the gold along with it. When the magma cools and solidifies, gold oozes out and forms veins or deposits within the surrounding rocks.

Where is gold found?

Gold is found in various places around the world, and the environment, geography, and type of gold deposit tends to be different depending on how the gold was formed. Gold deposits are classified in two main types: primary and secondary deposits.

Primary gold deposits

Primary gold deposits are where gold is found in its original geological environment, usually along the edge of tectonic plates or in regions with volcanic activity. These deposits form through magmatic or hydrothermal activity, as gold-rich fluids travel through cracks and fractures within a rock and cool, leaving behind deposits of gold and other metals. There are two different types of primary gold deposits:

  • Vein deposits: These are formed when gold-enriched hydrothermal fluids move through fractures in rocks. When these fluids cool, they form veins of gold-bearing minerals, such as quartz. These veins accumulate significant amounts of gold over time and create valuable deposits.
  • Disseminated deposits: These involve small particles of gold spread throughout the surrounding rock, rather than in concentrated veins. Disseminated deposits are usually formed with certain types of igneous rocks, where gold is disseminated through sulfide minerals.

How do you mine primary gold deposits?

Primary gold deposits are mined with underground or open-pit mining techniques:

  • Underground mining: This involves digging shafts and tunnels to access gold-bearing veins deep within the Earth. The ore is extracted and then processed to separate the gold from the surrounding rock.
  • Open-pit mining: Here, surface rock is removed to access the ore underneath it. This is more suitable for disseminated deposits where gold is spread throughout a large volume of rock.

Exploring and mining primary gold deposits can be complicated, however they tend to be the most valuable source of gold.

Continue reading: Gold Purity, Fineness, And Karat – What Is It And How To Check It

Secondary gold deposits

Secondary gold deposits, also known as placer deposits, are formed when primary gold deposits break down over time due to erosion, weathering, and water. This releases the gold particles within and redistributes them in new locations. Because gold is heavy and doesn’t corrode, it tends to accumulate along riverbeds, streams, or sedimentary environments. These deposits are where you would find gold particles, a gold nugget, or gold flakes, all eroded through the action of moving water.

How do you mine secondary gold deposits?

Secondary gold deposits are mined using surface mining techniques, such as panning, sluicing, and dredging:

  • Panning: This involves washing sediment in a pan to separate gold particles from other materials.
  • Sluicing: Here, water is flowed through a sluice box to wash sediment and capture gold particles.
  • Dredging: This process scoops up sediment from riverbeds or ocean floors and processes it to extract gold.

These methods are easier and less costly than those used for primary gold deposits, although they don’t offer the same abundance of gold.

Where does most of the world’s gold come from?

Gold is found in regions that have the geological processes necessary to form gold (i.e. extreme heat and pressure). Usually, these are regions with a history of tectonic or volcanic activity, or areas that contain ancient geological formations with gold-bearing rocks. These environments provide the ideal conditions for gold to form, deposit, and concentrate.

The world’s major gold-producing nations include:

  • China
  • Australia
  • Russia
  • US
  • Canada
  • South Africa.

When was gold discovered?

Gold is often considered to be the first metal discovered and used by humans. The earliest known evidence of humans interacting with gold is around 4,600 BCE in Bulgaria, where gold artifacts have been found in the Varna Necropolis burial site.

By 2,600 BCE, ancient Egyptians were mining gold extensively and revered the metal for its association with the gods and the afterlife. Around the same time, gold was also being used by the Sumerians in Mesopotamia and the Indus Valley civilization to craft jewelry and other artifacts.

Around 700 BCE, the Ancient Greeks were actively mining gold throughout the Mediterranean and Middle East. These operations were expanded upon by the Romans, who used techniques like hydraulic mining to extract gold from riverbeds. At this stage in time, gold was already being used for coinage.

During the 15th and 16th centuries, the Age of Exploration was marked by significant gold discoveries in the Americas, leading to an influx of gold into Europe. In more modern times, gold discoveries across the world ushered in ‘gold rush eras’, including the California Gold Rush in 1848, the Australian Gold Rush in the 1850s, and the discovery of gold in the Witwatersrand Basin in South Africa in 1886.

Keep reading: What are the Best Gold Coins to Buy and Why? From Kruggerands to Maple Leafs

How much gold is in the world?

According to the U.S. Geological Survey (USGS), around 244,000 metric tons of gold have been discovered on Earth to date. That’s around 7.8 billion troy ounces. It may sound like a lot, but due to its density, if you melted all the gold down it could fit inside a cube that’s about 75 feet wide on each side.

Most of the gold discovered in the world has come from just three countries: China, Australia, and South Africa. This gold is held in various forms, including gold jewelry (47%), investment bars and gold coins (22%), central bank reserves (17%), industrial uses (8%), and other purposes (6%).

See: Why Do Central Banks Buy Gold?

According to the World Gold Council, because gold is virtually indestructible, nearly all the gold ever mined is theoretically still accessible and potentially able to be recycled. Scientists also believe there's still about a million tons of gold within the top kilometer of the Earth's surface, waiting to be dug up.

Where could gold come from in the future?

Gold is largely considered to be a finite resource. What happens when the Earth’s gold reserves become depleted? Below, we look at where gold might come from in the future, including asteroids, the moon, and maybe even a laboratory.

Gold mining in space

The concept of mining gold in space is no longer confined to the realms of science fiction but might actually become a viable reality. Scientists are already exploring space mining technologies, and when it comes to gold we could have two options: mining asteroids and the moon.

Asteroid mining

Asteroids, especially those classified as M-type (metallic) are thought to contain significant amounts of gold, platinum, and other precious metals. These space rocks are remnants of the early solar system and often rich in metals that were never incorporated into planets.

Mining asteroids could potentially provide a limitless supply of gold, easing the strain on Earth's natural resources. A now-defunct company called Planetary Resources was already looking into expanding Earth's natural resource base by developing the technologies required to mine asteroids. More recently, a startup called AstroForge is also exploring the feasibility of asteroid mining. Stay tuned…

Lunar mining

Another potential source of gold (and other valuable minerals) is the humble moon. While not as metal-rich as asteroids, the moon’s surface contains resources that may potentially be valuable. We’re still exploring what those resources are exactly, but several missions are planned to find out, including NASA’s Artemis program - which is also looking to establish a sustainable human presence on the moon.

Future deposits from meteorites

The future of gold might also come from meteorites… they transported gold to Earth before, so why not again?

Meteorites are the remnants of asteroids and comets that survive their journey through Earth's atmosphere. They’re known to contain valuable metals, although most meteorites are small and don’t contain commercially viable amounts of gold. That said, larger impacts in the future could bring significant amounts of the precious metal to Earth. While difficult to predict and control, this could potentially be another source of gold in the future.

Can gold be synthesized in a lab?

What if you could manufacture gold in a lab? For centuries, alchemists have tried to transform base metals into gold, and theoretically, it’s possible. There have even been cases where scientists successfully created minute quantities of gold in laboratories using nuclear reactors and particle accelerators. However, these methods only produced a tiny amount of gold, and at an extremely high price.

So while it’s scientifically possible to synthesize gold, the process isn’t feasible for commercial or practical use due its high cost, low yield, and extreme complexity. Because of that, we’re unlikely to see synthetic gold production replace traditional mining and extraction methods. For now, it seems like Earth’s natural gold reserves seem to be the only way we’ll be getting our hands on this precious metal.

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