Who Is Actually Stealing the Iron from Our Earth’s Crust? Scientists Found the Culprit

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It took scientists years to learn who is the culprit behind the loss of our Earth’s iron in the crust. This week, scientists published their answer in the journal Science Advances, revealing who’s behind the iron depletion.

The previous belief was that the iron missing from the surface of the Earth’s crust was because a mineral inside the earth – magnetite, and volcanoes had something to do with it. The magnetite would absorb iron from the magma inside the volcanoes and then it would result in a crust low in iron. But new research found a different culprit.

It Was Not Magnetite After All

Petrologists Cin-Ty Lee, Ming Tang, Monica Erdman and Graham Eldridge of the Rice University in Texas found out that the real thief is garnet, not magnetite. Their study points out that if magnetite would have been the culprit, it should be more abundant in the continental crust. Lee explained:

“I think people haven’t thought much about garnet, possibly because it doesn’t show up very much and magnetite shows up in a lot of samples.”
The study found out that a garnet that is rich in iron – also known as Almandine is the one abundant in the thick crust of the Earth. Almandine forms with the help of high temperature and high pressure, deep in the continental crust. Researchers analyzed rocks formed at tens of kilometers depth (called xenoliths) which got scattered when volcanoes erupted. They found out that the stones contained a high amount of garnet.

Scientists also tracked the rocks from the GEOROC database at the Max Planck Institute to see if other rocks from different volcanic eruptions contained the same concentration of garnet. Their suspicions turned out to be out true.

Checking the Recently Available Global Database

Tang explained they will need to do more research, on a global scale:

“There is a relationship between iron depletion and the garnet fractionation signatures, which means magmas that fractionate more garnet are more depleted in iron. This is born out in the global record, but the evidence is something that wouldn’t be obvious from looking at just one or two cases. It’s the kind of thing that requires a global database, and those have only recently become available.”

Now that they all know that Almandine is the real culprit, scientists will be able to begin other studies to have a better understanding of the subject.

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Andre Blair s is the lead editor for Advocator.ca. He holds a B.A. in Psychology from the University of Toronto, and a Master of Science in Public Health (M.S.P.H.) from the School of Public Health, Department of Health Administration, at the University of North Carolina at Chapel Hill. Andre specializes in environmental health, but writes on a variety of issues.


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