4.4 billion-year-old crystal is oldest confirmed piece of Earth
cnn.comI just search a bit about Jack Hills. http://en.wikipedia.org/wiki/Jack_Hills The last modified was last December. The actual paper http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo20... was received last July but published on Fed 23, 2014. So it took a while to confirm and accept by the reviewers using the new technique.
And Jack Hills seems to have caught a lot of attention as early as 2006. http://earthobservatory.nasa.gov/Features/Zircon/ and in this article, 4.4B crystal was mentioned. So the actual paper we are reading today is really about using the new technique to confirm the age of the crystal.
"Among the first important discoveries, says Watson, came out in 2001."
Just think about an art from 10, 50, 100, 1000, 5000 and 10,000 years ago. Then think about this 4.4B years ago. It isn't mind-blown; it's scary to think about time. It takes millions of years for rocks to crush into each other and make a planet. What is it like to see things from 4.4B ago? Then think about the galaxy out there. People, the universe is an awesome and scary place.
Here is another article with an image explaining the idea of 4.4B with a personal phone interview from the primary investigator.
http://www.smh.com.au/technology/sci-tech/gem-found-on-austr...
Correct, this paper demonstrated that the Pb doesn't move around too far that it would invalidate the previous measurements. This was done using atom probe tomography.
Source: I know John and also do atom probe work.
Also, It was accepted at the end of last year and took a bit to publish, not unusual.
On a side note, JV is one of the most universally respected scientists I've seen. (JV --> John Valley, for various reasons everyone at Wisconsin calls him "JV".)
He's an absolutely huge name in the field, and actually treats his students/postdocs very well. He expects a lot in return, but he really does look out for people.
The almost incomprehensible age of the Earth was famously summarized thus:
“The reſult, therefore, of our preſent enquiry is, that we find no veſtige of a beginning,–no proſpect of an end.”
— Theory of the Earth, James Hutton, 1788
On a ſide note, we ſhould bring back the long S.
Yea, and alſo þe þorn! More seriously; it’s a text from 1788 – I’d think I was allowed to keep its spelling and not translate or transliterate when I’m actually quoting it verbatim.
It’s fine, I understood what you were up to. In earnest, though, I’d rather see thorn and eth come back than long S.
yes, that was annoying
Dumb question, would finding this just be pot luck, or did they have an idea of what they were looking at before they decided to subject it to the battery of tests?
Zircons are industrially useful as the primary ore for zirconium metal. If you keep it reasonably cool, like under red hot, it makes a great nuclear fuel rod protective cladding, assuming you refine out the hafnium which does little good in a fuel rod. Its also good for high temp ceramics, although too expensive for your fireplace, probably. If you get the metal red hot and dip it in water it does a fair impersonation of sodium being dumped in water at room temp. Unfortunately, recently, an extremely large demonstration of this effect was performed in Japan with predictable outcome.
Anyway there's lots of profit involved, leading to lots of geological research, leading to interesting discoveries.
Actually, there's a lot of research on zircons because they're useful for other research.
There are cases ("heavy mineral sands") where zircon is used as an ore, but essentially none of the research on zircons has anything to do with this.
Zircons have a number of nice properties:
1) They contain trace amounts of uranium and (initially) no trace amounts of lead. This allows them to be dated through U/Pb dating, which is relatively precise and is still accurate over _very_ long timescales.
2) They can undergo heating to very high temperatures without allowing lead to escape from the crystal lattice, resulting in the date being "reset". This allows dating of the original zircon grain even after the rock hosting it has gone metamorphism.
3) They're very durable physically and chemically. For this reason, they show up in sedimentary rocks and preserve a record of what was being eroded to produce the sedimentary rocks in question. Even when the sedimentary rocks have been changed into metamorphic rocks, the zircons are often preserved.
4) They're not very rare. Zircon isn't "main" rock forming mineral, but it's a not-too-uncommon accessory mineral in many igneous rocks (mostly in felsic magmas). Because zircons are so durable, they show up in sedimentary and metamorphic rocks sourced from the original igneous rock.
All of these reasons is why you'll see a lot of dating of zircons. They're somewhat common, durable, easy to date, and yield accurate results.
This leads to a lot of uses that you might not think of at first.
For example, if you want to know where (geographically) a given sedimentary rock was sourced from (i.e. what was eroded to form it), the most accurate way is to use the "age spectra" of the zircons within it. You basically disaggregate the rock, sort out the zircons (they're very dense), and date every single grain of zircon (and sometimes many zones on every grain). You take the distribution of ages that you get and compare it to the know ages of large igneous bodies that were likely to be exposed and eroding at the time. By matching the distributions (i.e. mixing models, etc), you can get an estimate of where sediment was being sourced from.
This may sound esoteric, but it's very useful for things like oil exploration.
I imagine they would have some idea of the age of the rock layer the crystal was found in and thus be able to approximate the age of the crystal before more advanced aging techniques become involved.
See my edit https://news.ycombinator.com/item?id=7299294
It has been found a long time ago on Jack Hills. But you are right, somehow, someone, a long time ago, walked on Jack Hills and found a crystal pretty old and started calling for interest.
It seems like it's a pretty small crystal (largest dimension is about the width of 4 human hairs - if I understand correctly). I'm curious as to how they actually found it...
Basically, they took chunks of what they already knew was a very old (~3.6 billion years old) rock, ground them up, separated out the zircon grains, and dated many (100's to 1000's) of individual zircon grains.
It would probably have been found by someone looking for the ages of rocks. In which case: probably sifted out of buckets of earth, looking for signs of extreme age. Seems like it's from a known-interesting area, which would attract that kind of crowd.
Isn't everything on the earth this old? The dirt in our backyard has been around for 4.4 billion years too. Or is it that this crystal hasn't been changed in that long?
It solidified from the melt 4.4 billion years ago and hasn't remelted since.
Or otherwise changed. Metamorphism doesn't involve melting.
When you put it that way, everything in the universe is the same age.
That's where I was going. What do they mean by age?
Although one could argue that the speed things travel through the universe alters their age, but from when the Earth materialized, it shouldn't change much from particle to particle.
If you're arguing for "oldest living thing" I do get it.
The dirt in your back yard hasn't been around for 4.4b years. Topsoil (decayed organic material and newly eroded rocks mostly) is usually pretty 'young' on geological timescales.
Not in that form, but the vast majority of the matter certainly has been part of the Earth for that long.
By the same definition, I'm not 40 years old either, because practically no part of me is left since I was born.
Right, but at least we can say you're a relatively old "living" creature where age is a more relevant number. (I'm getting up there in "relatively old" years too.)
We get new material thrown on us by space every day.
breaking news: scientist claims to have found quarks which existed since the big bang.
In reference to the comments on this article, it really is quite a sad day when creationism is reduced to the single "6500 years" theory by those who beg for people to have a more comprehensive approach to the subject (Read: those on the "side of science".)
It's somewhat of a double-standard critique.
Can we all agree that there are a massive number of views on this, and the range between the views is quite a bit closer to continuous than absolute?
For instance, there are those of us creationists who believe in the story of creation as somewhat allegorical, a cultural way of explaining a complex series of events that originated from an intelligent design, possibly including a singularity, evolution, and whatever else might be considered the "anti-creationist" view.
Isn't everything on Earth as old? It's all the same material that was there when the Earth formed, except for a few meteoroids that dropped on it later during its lifetime.
The same atoms, but in different combinations and configurations. What's newsworthy here is that this chunk of atoms has been in the same configuration for 4.4 billion years, and that the configuration can tell us something about the history of earth.
Atoms are actually of potentially different ages, but I'll get back to that. The important thing here is that it's a chunk of mineral, an arrangement of atoms, that can be confirmed to be 4.4 billion years old. There are atoms on Earth that are actually much older, as old as the Universe in fact. But there are atoms that are much younger too. For example, most commercial Helium comes from oil wells, where the alpha particles released by radioactive decay in rocks forms Helium and is trapped underground. This Helium is only a few million years old.
According to BBS Earth Biography series, half of all the water in the world came from a comet colliding to earth some 4 billion years ago.
The article does not seem to touch upon the possibility that the crystal was of extra-terrestrial origin.
At that time, I think the distinction is a little more fuzzy. The entire planet was of extraterrestrial origin.
The CNN article doesn't but it's a detrital zircon. It essentially has to be of terrestrial origin.
In other words, the zircon grain was found in what was at one point a sedimentary rock (now metamorphosed).
It formed in an igneous rock, was eroded, transported, deposited, lithified, buried, heated up, converted to a metamorphic rock, and then exhumed (actually all of this multiple times).
The zircon survived through all of that. (Which is why there's so much interest in making sure that the U/Pb ratio hasn't been altered by all of the rounds of deformation.)
However, extraterrestrial zircons have been found, and date back even farther.
This is the oldest piece of anything found that we know with reasonable certainty had to come from Earth.