Gold: The rich element

Gold represents a tiny fraction of the elements in the known universe. The reason for its rarity is owed to the incomprehensible amount of energy needed for its formation. Gold is formed in stars, but only in those that are exploding in giant supernovae, or incredibly dense ones that have come together in monstrously powerful collisions, according to the journal PNAS . 

Stars, such as our sun, generate energy through the power of fusion, where smaller elements are fused, or combined, together into heavier elements. To start with, a star may be mostly hydrogen, the smallest element. The process of fusion under immense pressure and heat in the star's core will generate helium. When hydrogen runs low and the star begins to reach the next phase of its life cycle, it will fuse helium into the next heavier element, and so on. 

This process continues until the element of iron, where the balance suddenly shifts. Because fusing iron does not create energy, it consumes it, according to the University of Oregon. With no means of generating internal energy to counteract its own immense pressure and gravity, the star begins to collapse onto itself. If the star is large enough the result is a supernova — a massive star explosion, according to NASA. Heavier elements are formed during the incredible energy generated during this process, including gold. 

Related: How can a star be older than the Universe?

Gold, and other elements heavier than iron, are formed just before stars explode into supernovae. (Image credit: Getty Images)

Very few other cosmic events can generate the levels of concentrated energy as within a collapsing aged star, but one that can surpass it is collisions between neutron stars, according to Space.com. Neutron stars are small and incredibly dense stars that fell short of becoming black holes. They generate huge gravity and can enter one another’s orbit. This can result in collisions of enormous magnitude, generating enough energy to form gold and other heavier metals.

Once flung out into the void of space, gold and other elements slowly came together to form the nexus of our fledgling planet. Over time, as the Earth cooled and separated into layers of core, mantle, and crust, the gold trapped deep within was forced toward the surface. Several theories have been suggested as to how this process occurs, but a shared theme is that heat and pressure forced liquid water upward, carrying dissolved gold as it travelled, according to the American Museum of Natural History. As the water cooled the gold precipitated out of solution, forming veins or lodes of concentrated gold. 

Over time, some gold travelled through the conduit of water yet further, up to the surface and into rivers. Here small nuggets of gold ran downstream. Perhaps the very first piece was encountered by a fisherman, who spied a glint, and dipped his hand into the water to recover the chunk of shiny metallic yellow. 

Thousands of years after this first occurred, gold prospectors and miners would treat gold nuggets in water as a sign of a lode nearby, and they’d busily get to penetrating the ground in search of gold veins to mine. Throughout the history of humanity many have died for gold, and many have killed for it, according to the Smithsonian magazine. But despite that, the story of where gold has taken our species is perhaps not as fascinating as where the element began.

Gold throughout history

Five thousand years ago, the massive Nile River was the key to the ancient Egyptian empire, according to the Australian government. Its water allowed a bounty of crops to be grown along its edge, keeping its citizens, and its armies, well fed. But there was also a shiny yellow metal that came running down the river, the element of gold. The Egyptians eagerly took this visually appealing treasure and found that because it was naturally pure and malleable, it required little refinement to be turned into mesmerising decorations. 

Egyptian Pharaoh Tutankhamun’s Funerary mask was made of gold and has endured for thousands of years. (Image credit: Getty Images)

Gold swiftly came to be a symbol, and unit, of wealth, and it has maintained this allure through time and around the globe. Several millennia after the Egyptian pharaohs and their tombs of gold, the Aztec Empire's gold riches were plundered by the Conquistadors who sought the valuable metal for their own. Later still, workers flocked to Western coast of the United States to take part in the California "gold rush", seeking their own fortunes, according to National Geographic. Therefore gold has driven humans to diplomacy, mass migrations, and even acts of genocide. Without this metal, our history would be quite different.

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Gold also plays a strong role in Australian history. In the late 19th century, so many flocked to the country to take part in its booming gold rush that the population of Australia tripled. Owing to its pervasive deposits, the country is still mined for the metal today, according to the Australian government. However, one company, named Evolution Mining, found a different treasure in their hunt for gold. When drilling into the Australian outback’s surface in search of gold deposits, the miners instead unearthed sheets of stone that resembled "shatter cones," which form on the outer rims of impact craters. They followed this finding with advanced mapping techniques that allowed the team to confirm the uncovering of a 5km wide meteorite crater, a finding even more rare than a lode of gold, according to Forbes.

Additional resources

• The Elements Book: A Visual Encyclopedia of the Periodic Table
• The Ages of Gold
• Seven Elements That Have Changed The World: Iron, Carbon, Gold, Silver, Uranium, Titanium, Silicon