Diamonds are one of the hardest and most valuable natural materials on Earth, prized for their beauty and industrial uses. Scientists have discovered that diamonds form under immense pressure and heat inside the Earth, primarily in rocks called metamorphic rocks. EclogiteOne question researchers are still investigating is how diamonds break down in the layers beneath the Earth's crust, the so-called “diamond layer.” Mantle, before reaching the surface.
Some researchers believe that rocks called igneous rocks Kimberlite The main culprit in destroying diamonds is kimberlite. Kimberlite is a dark-colored, porphyritic intrusive igneous rock that contains diamonds. Diamonds are stable at high pressures, but at high temperatures they break down or turn into graphite. Because kimberlite forms from extremely hot magma, scientists initially thought that the intense heat of the kimberlite magma destroyed some of the diamonds on their way to the surface. Kimberlite is also rich in a gas called argon. Volatile substancesVolatile substances may also react with diamonds, degrading them.
To study diamonds, scientists typically separate them from the rocks in which they are found. Researchers from South Africa, Germany and Canada have employed a new strategy to study diamonds without extracting them first. They used this method to look at how diamonds within eclogites in the West Kaapvaal Craton of South Africa and the Zimbabwe Craton formed.
Previous researchers had studied diamonds by trapping them in their native rocks, potentially damaging the diamonds in the process. But these scientists used X-ray-based techniques, Computed tomography scan Or they use CT scans to peer inside rocks without breaking them. Just like doctors use CT scans to look for fractures in the human body, these geologists used CT scans to see diamonds in rocks.
The researchers CT-scanned 24 South African eclogite specimens. They used a computer program to stitch together the individual CT scans to create detailed, three-dimensional images of the rock's interior before cutting it and extracting the diamonds. These images are like intricate maps that show the shape and location of the diamonds inside the rock, the researchers explained.
The researchers found that most of the diamonds in these rocks were single grains or crystalline clumps. The diamond crystals were shaped like eight-sided octahedrons covered with characteristic “steps.” They found that the step faces had sharp crystal structures and showed no evidence of fracture, as the crystal structures were still intact.
“However, some diamonds were also found to be rounded and partially destroyed, with their crystal structure broken. Groups of round diamonds within eclogites typically form in lines, which is consistent with changes caused by diamond-forming fluids. These fluid-based reactions occurred deep within the Earth during the diamond-forming process, not when the diamonds were transported to the surface with the kimberlite, the researchers explained.
The researchers analyzed the CT images and showed that some of the eclogite diamonds had been destroyed by a process called remelting or dissolution. absorptionThey explained that changes in the temperature, pressure, or composition of the magma could have caused the diamonds to be absorbed into the magma, and they suggested that this absorption occurred before the diamonds reached the surface, as opposed to the destruction that is presumed to occur within the kimberlite as it is transported to the surface.
The researchers concluded that more diamonds are being destroyed by absorption into the mantle than scientists had previously realized. However, they acknowledged that their interpretation was based on a selection of rocks from a limited geographic region. They suggested that future researchers apply their new CT scanning method to diamonds from around the world to see if this absorption process is widespread.
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Source: sciworthy.com
