Holding the Oldest

[CMD]

One of the most interesting of collectable rocks are rocks from space. Space Rox. Meteorites. I acquired my first from Robert Haag, the so-called meteorite man, in 1983. Haag is responsible for the modern era development of the hobby. Harvey Nininger was his predecessor, and the real inspiration for modern interest, but it was Haag who set the spark that led to the growth of the hobby.
Through this hobby, one can own pieces of the moon, Mars, the asteroid Vesta, etc. Collectors will tell you, to appreciate your space rocks, it helps to be a chemist. And it helps to be a petrologist. I'm neither, and weak in chemistry to boot. So you just do your best to bring yourself up to speed. The amount of info that can be extracted from these samples from other worlds is amazing, IMHO.
When the solar nebula was condensing into our sun and planets, our solar system, the first matter to form were little sphericules called chondrules:

http://en.m.wikipedia.org/wiki/Chondrule

Here Is a sample of an asteroid. A polished slice. Found in northwest Africa, either Morocco or Algeria. Those little spheres you see packed tightly are a cross sectional view of chondrules. So think of it as looking at the original matter of our solar system. Many of us collect rocks and minerals. The mineral kingdom justifiably famous for beauty. This slice of space rock has an attractiveness all it's own. And a wonder to hold, and behold as it were, an object from a beginning period in our solar family's history. ~4.6 billion years old. It has undergone weathering since arriving on Earth, oxidation evident in the reddened areas of the slice....



The unpolished side:

[Hoss]

Wow great picture and information Charlie thanks for sharing

[Lithophylic]

Question CMD, Several years ago, there was a discovery of a meteorite in Antarctica in which they tentatively identified fossilized bacteria and connected the rock to Mars.  You also mentioned a connection of meteorites here to the moon or mars.  My question is how?  How does one find a piece here and with our limited knowledge of these other bodies connect the two.  Thanks Nice slab.  I would love to see a thin section.  What is the matrix?

[CMD]

In the case of the Martian meteorites, there are several lines of evidence, but the smoking gun, as it were, was matching gases trapped within the meteorites to the composition of the Martian atmosphere. In the case of the lunar meteorites, the matches could be made by comparison to our abundant Apollo lunar samples. A little more detail in the case of the Martian meteorites here:

http://www.imca.cc/mars/martian-meteorites.htm

The Martian meteorites had always been viewed as different, since their absolute age was far younger then the ~4.6 billion years of asteroid samples. Therefore, they had to be samples of a planetary body large enough to have sustained geological processing long after the initial formation of the solar system. Mars had always been a prime candidate for these young samples.
Regarding bacteria in Martian samples, yes I vaguely recall the Antarctica story, and I believe the Mars meteorite called Nakhla, which fell in Egypt in early 1900's, has also had that claim applied to it.  I don't know the current status of any of the claims, but believe they are far from compelling at this point. Our Roger will know should he see this and weigh in here. It's actually been years since I actively collected and I will no doubt be rusty with the science.
Two slices of NWA 482, which samples the dark side of the moon.

http://www.lunarrock.com/history.html

http://www.lpl.arizona.edu/lplc/2002/abstract_volume/daubar.pdf

"The second largest lunar meteorite, Northwest Africa 482 (NWA 482), was recently found in the Sahara. It is also only the second lunar meteorite to be classified as a crystalline impact melt breccia. The rock contains abundant shock-melted glass in the form of several large pockets and veins cutting through the sample. The recrystallized matrix and the clast population are both highly anorthositic, indicating a highlands origin. Clasts include isolated plagioclase crystals and lithic anorthosites, troctolites, and spinel troctolites. KREEP and mare lithologies are both absent, constraining the source area of NWA 482 to a highland terrain with little to no KREEP component, most likely on the far side of the moon."

[painshill]

Nice specimens Charlie.
The Antarctic meteorite alleged to have biological remnant fossils was Allan Hills 84001 but rather than attempt to condense what is a very long story of claim and counter-claim, I’ll just point you to the Wiki summary:

http://en.wikipedia.org/wiki/ALH_84001

The jury’s very much still out on that one but the consensus is for scepticism (and even more so for the claims made for other Martian meteorites).
As for the question about how we know some meteorites are from Mars, it’s amazing how much the petrology and isotopic analysis can tell you. I have a tiny fragment of the Zagami Martian shergottite which has been tracked to a specific crater on Mars and it’s even possible to say which side of the crater it came from.
  Coming back to claims for "oldest"... this is a small slice of the Allende meteorite – a witnessed fall in Chihuahua, Mexico on 8th February 1969 - and is generally regarded as the most studied meteorite we have. It’s a carbonaceous chondrite, of which there are several classes (this one is a CV3) which represent less than 5% of known meteorites. Allende arrived in the stratosphere as a relatively fragile chunk of rock about the size of an automobile and detonated into several thousand fragments before hitting the ground.

You can see chondrules in this slice too, but those white structures with a slightly less regular outline are what are known as CAIs (calcium-aluminium-rich inclusions). Although some chondrules may be as old, these small structures are composed of what is believed to be the first material to solidify in solar nebula. The Solar System itself is around 4.568 billion years old and CAIs date to about 4.567 billion years (about 30 million years older than the Earth itself). Since they formed far away from the Sun, they represent the first material to cool below its solidification point and never came close enough to the Sun subsequently to remelt or mix. In fact they never again got above 200 degrees Celcius (apart from ablation effects on the exterior during atmospheric entry).
The CAIs in Allende were determined to have very unusual isotopic compositions which provide evidence for processes that occurred in other stars before the solar system formed. They contain forms of the elements calcium, barium and neodymium which are believed to have come from a source outside the early clouds of gas and dust that condensed to form our Solar System. They support the theory that shockwaves from a supernova (the death of an unknown but nearby star) may have triggered the formation of our solar system and probably contributed material to it. The presence of the isotope Aluminium 26 enables us to date that supernova event at less than 2 million years before the Solar System formed. In addition, Allende contains isotopic ratios of krypton, xenon, nitrogen and other elements whose forms are unknown anywhere else in our solar system. The nebular disc from which our solar System formed apparently contained “dust” from several nearby nova and supernova events as well as from red giant stars which are evident in Meteorites like Allende as tiny specks known as “presolar grains”.
Carbonaceous meteorites generally also contain a wide array of organic compounds including amino acids. Allende is rather poor in the content of these but the Murchison meteorite from Australia (a CM2) contains about 14,000 orgnanic compounds including 70 amino acids – some of which do not occur on Earth. I have a small piece of that one and make no apologies for the crappo picture because frankly there’s not a lot to see:

[Kyflintguy]

Truly fascinating guys I don't know what half of that means, but my take is old, rare, unearthly rocks from the beginning of everything B) and I think that's amazing! Thanks!
I want one! :whistle:

[chase]

LOL when I was holding the oldest it was this afternoon. and it was in liquid form, and well parts were. and it was a golden moment which went back into the universe. :whistle: Pee Whoohoo  :rolf:  :rolf:
Really neat!

[CMD]

Thanks for the wealth of information, Roger. Did not mean to neglect the CAI's of course, or deny them the status of "oldest".   I visualize chondrules as being original and  "erased" in all but the chondrites. I did mis-speak in calling them "oldest" but I think of the chondrites as "original rock" and "first rock". And in that respect I regard them as "oldest ".  Without a doubt, it is things like CAI's and what they represent that makes meteorite collecting so enjoyable and intellectually rewarding. And exciting to behold! Only recently have I been looking at my collection again. I've been very fortunate in some instances. This Allende for instance. 378 gm individual with fresh crust.

CAI inclusions visible as whitish inclusion on top. I used to describe it as star dust when showing the stone....

Secondary fusion crust. After forming fusion crust, stone fractures further while still in atmospheric flight, still time to begin to form another crusted over surface.


Allende is a special fall. I'm fortunate to own this individual. I would have a very hard time obtaining a specimen like this today. Certainly could not afford it, if I could find one this nice :dry:

[chase]

Really informational Thanks!

[CMD]

Regarding those older then dirt hmy: CAI's that Roger described. Here is another CV3 meteorite in the same Carbonaceous Chondrite group as Allende. In this case, a slice of Vigarano (the V in CV3). The white splotches are the Calcium Aluminum Inclusions that predate our solar system. Vigarano fell in Italy in 1910. The chondrules are also visible in this slice.....

[Kyflintguy]

I've always had a interest in astronomy and space in general.  In grade school I was president of the "Rock Star" club (geology/ astronomy)  very corny I know inch: .... but I was wondering,  I know there was  a danger of hazardous particulates duiring the Apollo program moon rock collecting. Was this just the dust contaminants, or were these elements chemicaly hazardous to your health? Could there be potentially dangerous elements present  in meteorites from outer space? Just curious. ...

[CMD]

Josh, I don't think so, but I'll defer to Roger. He's been involved with meteorites even longer then myself. In the meantime, I found the perfect CAI sample. It's an Allende fragment belonging to my wife, and really shows that early matter. I still think of chondrite meteorites in general as being the oldest rocks I can hold.
The white splotch at the bottom, and others visible as well....

[painshill]

Kyflintguy wrote:

I've always had a interest in astronomy and space in general.  In grade school I was president of the "Rock Star" club (geology/ astronomy)  very corny I know inch: .... but I was wondering,  I know there was  a danger of hazardous particulates duiring the Apollo program moon rock collecting. Was this just the dust contaminants, or were these elements chemicaly hazardous to your health? Could there be potentially dangerous elements present  in meteorites from outer space? Just curious. ...

  There were strict quarantine and decontamination procedures in place for all space missions involving extra-vehicular activity, and especially for the Apollo landings. To a large extent these were designed to counter any public concern and international criticism rather than reflect any expert view that something toxic or infective might be brought to Earth. Those possibilities were regarded as remote. The real concerns about dust related to the effect it might have on the workings of the lunar module and subsequent transfer into the command/service module. NASA underestimated the amount of dust that would accumulate on the suits used by the astronauts who went walkabout and that was compounded by the fact that several of them fell over into the moondust during their excursions. There was enough dust in the atmosphere of the return modules for astronauts to get a “smell” of the moon and several of them likened it to the smell of gunpowder.
Incidentally, there are only two meteorites I know of which had any appreciable radioactivity, but we’re talking levels which are not much above the background levels you might find on Earth and much lower than you might experience if you lived somewhere that sits on granite bedrock – the Edinburgh area of Scotland for example.

[CMD]

Funny, I changed the subject title here from "Beginnings" to "Holding the Oldest" and then proceeded to put chondrules first. Should have left the original subject title since what I was really trying to illustrate was what the oldest rocks you can hold in your hands look like. Carbonaceous Chondrites like the CV3's let you see that earliest of material, the CAI's. And when you are holding a chondrite stone meteorite, I hope it's fair to say you are holding close to the original material of our particular solar system. Close to holding the beginnings? Won't hold any Earth rocks this old....

[lukecreekwalker]

Really interesting.  Josh, I was the leader of the "science club" in 3rd grade and I lugged old Encyclopedia's to school so we could look at pictures of the planets.  I've always liked space as well. 
One Christmas I got a decent telescope and the first time I saw the 4 major moons of Jupiter through them, the nebula in Orion, and Saturn's rings I was amazed.  Still am.  To own a piece of it is very cool.  I especially like the Moon pieces you have.  Thanks for showing and here is a little link to show you how small we are haha

http://www.mandatory.com/2015/02/09/earth-in-true-perspective-shows-us-just-how-insignificant-we-act/