One would naturally think that the most abundant mineral on earth would be heavily studied and documented by this point in human history. However, that couldn’t be further from the truth. In fact, the most abundant mineral on Earth had never even been named. How is this possible? The mineral lies deep within in the Earth’s mantle and scientists had no natural sample in their possession until now.
Oddly enough, the sample was found on a sample of an object not from this Earth. In a study published this week in the journal Science, researchers discuss how they found the elusive, yet abundant, Earth mineral, and what it means for future studies.
According to Space.com, the mineral is a high-density version of magnesium iron silicate. It is the most abundant mineral on Earth, and makes up about 38 percent of the planet’s volume. But it’s only stable at very high pressures and temperatures, so for decades, researchers had only seen lab-generated versions of it meaning that the mineral had to remain nameless as International Mineralogical Association requires a naturally occurring sample for naming.
“Under the heat and pressure found in Earth’s lower mantle, which extends from about 410 to 1,615 miles below the planet’s surface, magnesium silicate can form what is called a perovskite structure, which can be imagined as an array of double pyramids that are joined at their corners. The centers of each pyramid are made of silicon, the apexes and corners are made of oxygen, and magnesium and iron reside in the spaces between each double pyramid. But scientists had not discovered a naturally occurring version of this mineral until now.”
However, the mysterious mineral was found in the Tenham meteorite, a rock that was part of a meteor shower that rained down on Australia on a spring night in 1879. On this meteorite, scientists were able to identify for the first time the mineral now named bridgmanite. The name was an ode to the father of high-pressure experiments, Nobel laureate Percy Bridgman.
Scientists have been searching for a natural sample of bridgmanite for over a decade, but had been accidentally turning the samples into glass by attempting to use electron microscopes for viewing. The electron beams used in the microscope would cause the bridgmanite into glass and it would lose its structure. However, this time scientists used high-energy x-rays to prove its composition.This did not disturb the bridgmanite and scientists were able to get a structural glimpse of Earth’s most abundant mineral for the first time in history.
This is exciting news for geologists, who will now be able to better understand the physical processes at work in the Earth’s mantle. Bridgmanite proves that there is still much to be learned about this planet we call home.