Diamonds are not just a woman's best friend. They are also geologists' best friends. These gems sometimes contain incredibly rare or invisible elements that reveal the deepest secrets buried in the bowels of our Earth. Analyzing such finds, scientists were able to guess what is underground and even revealed some facts from the history of our Earth. On rare occasions, diamonds come from space.
10. Ringwoodite
Scientists believe there is an ocean inside the Earth's mantle. This ocean is located inside a green mineral called ringwoodite, deposits of which exist only between the lower mantle and the transition zone inside the Earth, which is 515 kilometers thick. The transition zone is located between the upper and lower mantle.
Ringwoodite cannot be found on the surface of the earth because it can only be obtained under the insanely high pressure that is deep underground. Scientists reached it several times, but each time the mineral changed its shape in the absence of massive underground pressure. However, geochemist Graham Pearson succeeded in obtaining ringwoodite in its natural form.
Ringwoodite was trapped inside a diamond found in a mine in Juina, Brazil. Pearson and his colleagues have suggested that the mineral rose to the surface during the earthquake. Pearson made the discovery by accident. He was trying to date the diamond when he discovered it contained ringwoodite.
Promotional video:
9. Perovskite calcium silicate
Paradoxically, silicate perovskite is a rare mineral, although it is the most abundant mineral on Earth. Scientists believe that 38 percent of the Earth's volume consists of silicate perovskite. However, it is so rarely found that the first sample came from a meteorite believed to have split off from another planet. We cannot get to silicate perovskite on earth because it is only found inside the earth's mantle.
That changed, however, when scientists discovered a stable sample of the mineral inside a diamond, just 1 kilometer underground at the Cullinan diamond mine in South Africa. It turned out to be calcium silicate perovskite (CaSiO3), believed to be the fourth most abundant mineral on Earth.
Interestingly, the diamond that contained the sample is one of the rarest diamonds on Earth. It can be found about 700 kilometers underground, where the pressure is 240,000 times that of the surface. Scientists believe that a sample of calcium silicate perovskite was trapped inside the diamond as it formed.
8. Ice
As we mentioned earlier, scientists have put forward the assumption that there is an ocean inside the Earth's mantle. Scientists believe that this ocean was formed when water from the oceans of the planet went underground along with parts of the earth's crust.
Scientists know that the earth's crust is still sinking into the mantle. But they cannot determine how long it has been doing, and how large the underground ocean is. As far as we know, it may not even exist. However, recent discoveries suggest that it does exist.
In March 2018, it became known that scientists had discovered ice samples "hidden" in diamonds that formed in the Earth's mantle. They believe that the ice was created from water "pulled" into the mantle. This discovery becomes more interesting when we realize that it is very hot inside the Earth, and ice does not form in a hot environment.
Scientists call this ice VII, and it only forms at a depth of 610 to 800 kilometers underground, where pressures exceed 24 Gigapascals. So far, three ice-VII samples have been found in diamonds: two of them were found in mines in South Africa and the third in a mine in China.
7. Liquid metals
All large diamonds ever found were formed deep within the mantle at depths between 322-805 kilometers. These diamonds sometimes contain impurities that are actually metals present inside the Earth's mantle. Scientists often study these diamonds to get an idea of what is in the mantle.
After analyzing 53 of these diamonds, scientists found that the Earth's mantle contains a lot of iron and nickel, as well as traces of methane, hydrogen and garnet. Interestingly, they found no trace of oxygen. This contradicts the assumption that there is a large amount of oxygen inside the mantle.
6. Harzburgite inclusions
You have probably never heard of harzburgite inclusions, a type of rock. It is a subcategory of peridotite rocks, which are the most abundant rocks found in the Earth's mantle. Due to their abundance in the mantle, scientists often date diamonds based on the harzburgite inclusions they contain.
Several researchers at the Vrije University of Amsterdam have made an interesting discovery by dating 26 diamonds containing harzburgite inclusions. Nine of these diamonds were formed about three billion years ago, when a large continent split into smaller continents, causing a massive rise in temperature deep underground.
The researchers found that 10 of the diamonds were only 1.1 billion years old, which is very small on the Earth's scale. In fact, it was the first time scientists have found diamonds that are a billion years old. These gemstones are typically several billion years old because the Earth was extremely hot at the time. And one billion years ago, the planet was too cold for diamonds to form.
However, scientists believe that the required temperature was provided by a powerful volcanic eruption that occurred in the territory of modern Zimbabwe. Their discovery allows a new look at the technology of diamond mining, since in promising mines, developers often check the age of harzburgite inclusions.
5. Boron molecule
Typically, carat weight is one of the factors that determine the value of a diamond. The higher the carat weight, the higher the price, and vice versa. However, the color of the diamond (which is due to the presence of other minerals) also affects the price. The more rare it is, the higher the price. Blue diamonds are the second rarest diamonds and they are quite expensive. (Red diamonds are the rarest).
In 2016, a 24.18-carat Cullinan Dream blue diamond was auctioned for $ 23 million. Blue diamonds are rare because they are the deepest diamonds. They form deep within the lower mantle between 410-660 kilometers underground. By comparison, ordinary diamonds form between 150-200 kilometers underground.
The color of blue diamonds is due to the boron they contain, which is rarely found underground. Most of the world's boron reserves are found on the surface in the Earth's oceanic crust. So how did boron end up in the lower mantle and even inside the deepest and second largest diamond in the world?
Scientists are unsure, but they speculate that boron enters the ground when a denser tectonic plate falls down and sinks under a less dense tectonic plate. Then boron from a dense tectonic plate falls underground along with methane, hydrogen and ocean water.
4. Kyanite
Although rare, sometimes other gemstones such as ruby or kyanite are found in diamonds. We have already mentioned that diamonds are blue when they contain boron, but they can also be blue because there is kyanite inside.
Kyanite can also be gray, green, orange, white, yellow, or even colorless. Blue kyanite is the most valuable, although white kyanite is less common. Fraudulent sellers sometimes pass off blue kyanite as a more expensive sapphire.
3. Mutated carbon atoms
Pure carbon comes in three main forms: diamond, graphite, and buckminsterfullerene. However, scientists have discovered two other forms that contain mutated forms of carbon, making them harder than diamond. Interestingly, scientists predicted the existence of these crystals long before their existence was confirmed.
Superhard crystals were not found on Earth. Instead, they were contained in the Ureilite-class Havero meteorite that fell in Finland in 1971. Meteorites of this type often contain graphite and diamonds.
Scientists believe the superhard crystals were originally graphite, which heated up when the meteorite entered the Earth's atmosphere. This triggered a chemical reaction that caused the carbon atoms to mutate, creating a superhard crystal.
Unfortunately, scientists were unable to determine the hardness of the crystals because they were too small. However, they were harder than diamond because they could not be polished with diamond grit.
2. Carbon-12
In 1983, at Jack Hills in Western Australia, researchers from Curtin University discovered 22 diamonds inside several zirconia crystals. Research into diamonds has shown that they are composed of carbon-12 (aka light carbon). The find was surprising because diamonds, which contain huge amounts of carbon-12, are only formed when there are living organisms around.
Scientists have found that diamonds formed 4.2 billion years ago, and zirconium - 4.4 billion years ago. Scientists have always believed that the first single-celled organism appeared 3.5 billion years ago. However, diamonds have proven that unicellular organisms probably existed during the Gadean eon, 700 million years earlier.
At that time, the Earth was a terrible place to live, even for the tiniest organisms. It was very hot on the planet. Instead of water, the ocean was filled with ultra-high pressure magma. Scientists suspect that if carbon-12 was created by living organisms, then it could be brought to Earth by meteorites.
1. Ferropericlase
It is rare to find diamonds that have formed very deep in the Earth's mantle. However, researchers at the Gemological Institute of America believe they may have found several of these minerals. These diamonds contain ferropericlase, which is found deep within the Earth's mantle.
Ferropericlase-containing diamonds are easily recognizable because they are iridescent. They change color depending on the angle at which they are viewed and the angle of incidence of light - as happens with a soap bubble. No one knows why ferropericlase diamonds behave this way, but one of the possible reasons is the presence of magnesioferrite in them.
However, not all diamonds containing ferropericlase are capable of sparkling in different colors. Some are just translucent brown. In addition, the presence of ferropericlase is not sufficient evidence that the diamond was formed in the mantle. These diamonds can also form high above the mantle where quartz is scarce.