As they say, diamonds are forever, and gold is precious. But which of them is less common? And does this rarity have anything to do with the price you see in jewelry stores?
The answer is not as simple as you might think.
Gold and its concentration in the earth's crust
A heavy metal, gold is one of the rarest elements on Earth that was formed by the collision of neutron stars. Then, in the process of the formation of the Earth, the heaviest elements went under the influence of gravity closer to its core. This means that it is very difficult to find large quantities of gold near the Earth's crust. However, it can be found in low concentrations. It is found in a wide variety of rocks in the earth's crust. But in order for a full-fledged deposit to form, gold must have a certain concentration, such that its extraction will be economically justified. The average concentration of gold in the Earth's crust is very, very low, about 4 parts per billion. In order for the concentration to be sufficient for the formation of a deposit and the start of gold mining,it should be about 1250 times higher.
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Diamonds
Diamonds, on the other hand, are a very high pressure, very common element, carbon. In its standard, non-high pressure form, it is known as graphite, which is what pencils are filled with. Compared to gold, the average concentration of carbon in the Earth's crust is about 200 thousand parts per billion. Thus, the rarity of diamonds has nothing to do with their elemental composition. Rather, it is about the natural transformation of carbon into minable diamonds, an incredibly difficult (and rarely successful) process.
The process of making diamonds
Diamonds can only appear in the Earth's mantle (the layer of the Earth located under the crust) and rise to the surface in some way. Or they can be formed by impact with a meteorite, but such diamonds are usually small and not of high value. Diamonds that appear deep in the Earth's mantle can rise upward thanks to magma. Or, they may appear higher due to the slow growth process of the mountains, which pushes them out of the mantle. However, during this slow process, diamonds very often graphitize, that is, they turn back into graphite, on the surface they are no longer precious stones. The formula required to form diamonds depends on several factors such as depth, temperature, and pressure. Carbon is located at a depth of at least 150 kilometers from the Earth's surface, heats up to about 1200 degrees Celsius at a pressure of about five billion pascals, after which it is quickly carried to the Earth's surface, for example, by a volcanic eruption, where it cools down and finally turns into a precious stone. This incredible process makes natural mined diamonds significantly rarer than gold.
What is less common?
However, in its elemental form, gold is considerably rarer than diamonds. Yet carbon is one of the most abundant elements on the planet, especially when compared to heavy metals like gold, and a diamond, simply put, is carbon under incredible pressure. The invention of synthetic diamonds further complicates the matter. Scientists can recreate the specific conditions required to transform graphite into diamonds in the laboratory (without the need for a volcanic eruption), but the same cannot be said for gold (unfortunately alchemy is still a pseudo-science).
Although synthetic diamonds are made from the same substance as natural diamonds, synthetic versions usually sell for 30 percent less on the market because they are not considered to be as valuable. But does the existence of lab-created diamonds make them less rare than you thought? It’s worth starting with the fact that diamonds under a certain size are not worth mining. Who wants to buy a diamond that can only be seen through a magnifying glass? Gold is more common than large diamonds, however diamonds as a class of materials are not rare. They owe some of their reputation to incredible PR.
Author: Marina Ilyushenko