Wednesday, January 7, 2015

Philosophy Wire: Bridgmanite. Naming things. Emptying the mantle.

Philosophy Wire by Spiros Kakos [2015-01-07]: A team of geologists in the U.S. has finally found an analyzable sample of the most abundant mineral in the world allowing them to give it a name: bridgmanite. In their paper published in the journal Science, the team describes how they were able to analyze a sample of the mineral in a meteorite. Thomas Sharp of Arizona State University offers an analysis of the research in the same journal issue.

Earth scientists have known about the mineral (which is made up of high density magnesium iron silicate) for quite some time, it makes up approximately 70 percent of the Earth's lower mantle which amounts to 38 percent of the Earth's total volume. But it doesn't exist on the planet anywhere else, at least not in samples that have been found. Prior to now, it was referred to as perovskite because according to rules set down by the International Mineralogical Association, a mineral cannot be given a formal name until a specimen has been found that can be examined first hand. The new name is in honor of Percy Bridgman, a pioneer in the use of high pressure experiments to better understand how many geological formations come about.

Because it's not possible to dig down to the lower mantle to obtain a sample of the mineral, scientists have had to look to other sources. Prior research had suggested that it could likely come into existence when two celestial bodies collide—the shock waves could provide the enormous pressure needed. During such a collision, which would involve damage to both colliders, pieces would undoubtedly be flung to the far reaches of space, some of which could make their way to us in the form of a meteorite. In this latest effort, the researchers looked at a likely candidate, a meteorite that had fallen to Earth in Australia in 1879.

The scientists finally analyze the sample in a way that confirmed the mineral was in fact, perovskite.
The researchers noted that the sample has more sodium and ferric acid than had been expected—and their finding is expected to aid in future geological research efforts, and might even hold clues about what goes on when celestial bodies collide, which in turn could offer more insight into the formation of the universe. [1]

We want to name things.
But in order to do that, we must first know them.
But we cannot know them unless we name them.

Name things and you will destroy them.

The mantle is full of something.
But not that thing you think.
Bridgmanite no longer is.
It is in the books now.
The mantle is empty...

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