Diamond hauled from deep inside Earth holds never-before-seen mineral | Hacker News Reader

Diamond hauled from deep inside Earth holds never-before-seen mineral

livescience.com

119 pointslxm32 comments

In case you are wondering:

> Named davemaoite after prominent geophysicist Ho-kwang (Dave) Mao, the mineral is the first example of a high-pressure calcium silicate perovskite (CaSiO3) found on Earth.

To add to the tl;dr: the "never-before seen" is long since theoretically known, but davemaoite usually breaks down on its way up to the surface.

The most interesting part or me was that the diamond came from 600km below the earth's surface. Maybe this is common knowledge, not for me. It's pretty cool to think that we have access to such things. If we could dig down that far, would there be an abundance of diamonds?

The article says the diamond formed at that depth, but I assume the rock rose to a higher depth before it was extracted. I believe the deepest depth to which we have drilled is on the order of 10 km.

The Kola borehole, drilled by the Soviets, is the deepest we've ever drilled, at 12.2 km.

To save you a search https://en.m.wikipedia.org/wiki/Kola_Superdeep_Borehole

I've alway wondered why they never went deeper. Turns out the answer is in hindsight obvious, but very unsettling:

> The unexpected decrease in density, the greater porosity, and the unexpectedly high temperatures caused the rock to behave somewhat like a plastic, making drilling nearly impossible.

We could use the unexpectedly high temperatures as a heat source for geothermal energy. Make money selling the energy for ten, twenty years,... until the temperatures fall and the rock becomes rigid. Then drill another kilometer, funded from the geophysical exploration budget.

Temperature too high again? Have a long pause to make a little money from geothermal energy.

Geothermal plants can trigger earthquakes [1], so it's probably unwise to build a lot more geothermal plants to meet global energy needs without addressing that risk first, especially near populated areas.

[1] https://news.stanford.edu/2019/05/23/lessons-south-korea-sol...

My favorite thing about that hole is that we always imagine it to be human-sized or something, but it was as wide as a football or so.

There's an abundance of diamonds right here on the surface (or near it). Diamond supply is artificially constrained.

And we can manufacture them cheaply.

They were transported to the surface with eruptions ten to hundred millions of years ago. Google «Kimberlite».

A few micrometers in size. I dont think in micrometers, so I must convert to a more familiar unit. A few .001mm in size. That's tiny. An average piece of paper is .1mm thick. This is around the size of the thickness of ink on the paper.

30 or so coronaviruses side by side.

How many would fit in a football field?

Like, a grip of library of congresses worth?

A few micrometers is around 1E-4 inches or 3E-6 yards for those of us who think in freedom units (aka real units).

You joke, but this would (perhaps even more absurdly, really) be called a "tenth" by most people who care about imperial units at this scale (as explained in a sibling comment)

This is pretty anti-intellectual isn't it? People, in my opinion rightly, make fun of measures expressed in libraries of congress or Olympic pools or African elephants, and then an article actually uses a normal SI measure and that gets disparaged too? What are authors supposed to do?

There was nothing disparaging about the comment. There is also nothing anti-intellectual about comparing things you don't know to things you do, in order to contextualize information. And he did that by first converting to mm, so did not abandon SI measurements at all. I agree that when we are talking about more common measurements it can be gratuitous or grandstanding, much like talking about things over 1x size in percent, as e.g. 450% bigger, etc. But that is not the case here.

Yeah, for folks with experience in machining (in the US), this is a "tenth" (a pretty fundamental unit in machining is a thousandth of an inch, or a "thou", for very high precision work, that can be divided into "tenths", or ten thousandths of an inch).

A mil, or a thou, really isn't good enough for high precision work. 25.4 microns is a lot. A surface flat to that isn't really that flat. An instrument that measures to that isn't really a very high precision instrument. Microns are a pretty good unit.

EDIT: There's this rule of thumb (I might be getting this slightly wrong) that one in a million accuracy/precision is about what you can expect to achieve without resulting to exotic means (at least order of magnitude). So microns of flatness over a meter e.g. Trying that with imperial units just breaks my mind, what's a million mils. Sure I can calculate that. But it's like a pretty useless measure. So accuracy of one thou over a million mils is sort of weird. (1000 inches which I'd have to translate to some normal unit... 25.4 meters ;) ).

Yeah, that's why tenths (~2.5 microns) are used when thousandths aren't precise enough.

I'm definitely not claiming it's a good, I'm just describing the system I have seen used in the handful of machine shops I've spent time in.

I think YZF just mis-parsed your sentence, and thought you meant a thou is for very high precision work, while you meant that a tenth is for very high precision work.

(That said, I'd add -- measuring to one part in 10^6, for anything except time, is challenging but still very doable; machining to one part in 10^6, for anything beyond very simple shapes, does require pretty exotic methods or very great care, and to verify it you have to measure to one part in 10^7).

Oh, yep, there's an extra comma that makes my comment a bit ambiguous. Alas, it's outside the edit window...

I think "a tenth of the thickness of a human hair" would be an appropriate layman description of the approximate size.

Previous discussion: https://news.ycombinator.com/item?id=29209015

It's always strange to thing of the vast distances we can send things into space compared to our inability to travel extremely short distances beneath our feet.

To be fair, theres a lot more stuff in the way traveling downward

Anyone else have a constant reload of the site no matter what I do it reloads within seconds?

I love this naming convention, I didn’t think that happened anymore.

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