Gold is a heavy metal, a rare element of the Earth that forms in space when neutron stars collide. But just how rare is gold on our planet, and what is its monetary value today?
The best way to address these questions is to look at the amount of gold that has been mined by humans up to this point. The US Geological Survey (USGS) estimates that throughout history, approximately 206,000 tons (or 187,000 metric tons) of gold have been extracted from rocks and rivers. Nowadays, much of the gold used for jewelry is mined and produced.
This estimate is notably lower than the figure provided by the World Gold Council, which states that currently, around 238,391 tonnes (or 216,265 metric tonnes) of gold have been mined. This amount would fit into a cube approximately 72 feet (22 meters) on each side. About 45% of this gold is crafted into jewelry, 22% is held in the form of bars and coins, and 17% is stored in central bank reserves, according to the Council.
Humans have extracted a significant portion of gold from economically viable sources in the Earth’s crust, yet reserves still exist. According to the latest USGS mineral commodity summary, the Gold Report indicates that approximately 70,550 tons (or 64,000 metric tons) of gold remains in economically viable deposits around the world. The report identifies Russia, Australia, and South Africa as the leading countries with untapped gold reserves, while China has mined the most gold in 2024, bringing it to market.
Experts differentiate between reserves—sections of mineral deposits that can be economically extracted—and resources, which refer to ore deposits that researchers and companies believe can be extracted based on geological knowledge. According to Metal Focus, global gold reserves total approximately 60,370 tons (or 54,770 metric tons), while the estimated amount of gold resources is around 145,626 tons (or 132,110 metric tons).
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Combining estimates from USGS and the World Gold Council suggests that humans, along with known crustal sediments, have around 277,000 to 299,000 tons (or 251,000 to 271,000 tons) of gold. However, there remains considerable uncertainty regarding these figures.
Moreover, most gold on Earth is not concentrated in large deposits but is found as small particles and nuggets scattered throughout the crust. These tiny particles can be especially prevalent in seawater and igneous rocks, according to the University of California, Berkeley. The concentration of gold within the Earth’s crust is roughly four parts per billion, translating to about 441 million tonnes (or 400 million tonnes) of gold particles in total, as noted by the Royal Mint.
Although this may seem like a significant amount, it represents only a small fraction of the total gold available on our planet. Geologists suggest that the vast majority of Earth’s gold is trapped in its core, estimating that 99% of the world’s gold resides there. A mere layer of 1.6 feet (0.5 meters) could envelop the entire planet.
During Earth’s formation, most of the available gold descended into the planet’s core due to its density, as explained by Chris Voisey, an ore deposit geologist and researcher at Monash University in Australia.
“Consider that 99.5% of the Earth’s mass formed when elements melted and separated according to density, causing gold to migrate to the core,” Voisey noted in an email to Live Science. The remaining 0.5% landed on Earth during a “late intense bombardment” between 4.1 billion and 3.8 billion years ago, when the planet was aggressively hit by meteoroids. This 0.5% contains the gold currently found in rocks explored by geologists and resource hunters; it has concentrated into today’s ore deposits, according to Voisey.
This small percentage of Earth’s mass was not trapped in the core, as the planet had already formed a solid crust upon its arrival. Voisey said, “Many of the Earth’s precious metals that comprise ore deposits are believed to have originated from this event, as they are not confined to the iron-nickel core.”
Since this intense period of bombardment, the total quantity of gold on Earth has not changed appreciably due to extraterrestrial inputs. Voisey mentioned that deliveries of gold via meteoroids are “more or less negligible,” asserting that the existing gold on Earth is “simply redistributed by geological processes that create ore deposits.”
Given that a significant amount of gold lies in the Earth’s core, and its concentration across the crust is highly uneven, Voisey expressed serious doubt that researchers will ever be able to accurately quantify all the gold on Earth. He also remarked that it is “impossible” to accurately determine the amounts of gold that remain undiscovered by humans.
Source: www.livescience.com