Meteorite Monday: The Chondrule Controversy

The rounded objects in the Grassland chondrite are chondrules (image from Wikipedia).

The rounded objects in the Grassland chondrite are chondrules (image from Wikipedia).

One of the more heavily  debated topics within the field of meteoritics is the origin of chondrules. These are the small, spherical silicate inclusions from where we derive the technical name for the most common type of meteorites, the chondrites. With few exceptions, chondrules are found in all chondrite groups in varying quantities. Sometimes we’ll see chondrites that are nearly 70% chondrules and in other cases, we’ll see chondrites, such the Ivuna, that contain no chondrules. In the simplest of terms, chondrules are composed of olivine and/or pyroxene, occasionally glass and a smattering of feldspar. In not so simple terms, chondrules are a hot mess of textures and compositions- messy enough that I’m not going to cover it in this post, but I did delve into it a bit in this older Meteorite Monday post about our enigmatic friends. Continue reading

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Meteorite Monday… er, Tuesday!

Believe it or not, I’ve missed my blog. I’ve missed interacting with my readers and talking about all the cool science occurring in meteoritics and planetary science. A few factors have contributed to my absence from blogging: school/work load, my work in the meteorite lab, and a general burn-out over the course of the academic year. I essentially worked myself into the ground during the Fall and Winter term and the Spring term has been my recovery period. That and it’s difficult to get back into blogging when you’ve been away from it for a period of time. I’m hoping to change that though with more regular posts.

So, as a way of easing back into the blog I thought I’d start with a new Meteorite Monday Tuesday! This time I’m going to talk a bit about a project that has consumed a great deal of my time: the shock dike in my meteorite. And since this is all available in the poster I did for LPSC, I don’t have to worry about revealing information intended for the publication.

Here’s a simple slide of the shock dike that I’ve been working on for the past year or so:

Advection and diffusion in the Buck Mountains 005_003

What you’re looking at is a transmitted light image of the meteorite I’ve been working on. That thick, black structure from the lower right corner to the top left corner is what we’re referring to as a shock dike.  This isn’t something that’s been studied before, so our term isn’t one that’s been utilized in the past. In fact, I ran into some resistance to the term at LPSC because the term dike is traditionally used in a terrestrial setting and not that of an extraterrestrial. What some people forget is that we apply earth based geophysical and geochemical analogs to other bodies in the solar system all the time. It’s that application that allows us to understand the forces that shape the other rocky planets.

Here’s what we know about the formation of shock veins, and by extension, this shock dike. We know they form as a result of a collision in space. The kinetic energy from that collision would become the heat needed to melt a large portion of the rock. That melted rock acts a lot like water- it flows through cracks and exploits areas of weakness within the solid rock structure. That sudden influx of melted rock also drives up the pressure and changes the  minerals it encounters into high pressure polymorphs- or minerals with the same chemical composition, but a more compressed crystal lattice structure.  Such minerals become encased in the rapidly cooled vein and don’t have the chance to change back to their preferred structure. 

What makes the shock dike unique is that it didn’t cool quickly and there are no high-pressure polymorphs. Everything pretty much melted. The heat needed to melt the rock was produced by an impact and sustained through friction as the rock sheared like a strike-slip fault. This sustained heat and mechanical grinding vaporized the less heat tolerant feldspars, and melted pieces of the more heat resistant pyroxenes and olivines. As these minerals broke down they added their chemical components to the melt. This, combined with a relatively long cooling time, caused new minerals to form out of this melt. Such minerals include pyroxenes composed of alternating bands or iron and magnesium and aluminum rich pyroxenes; all indicative of crystals that grew from a melt.

Picture1

This is a false colored back scatter electron image of the shock dike. The salmon colored minerals in the inner dike are olivines and they correspond to the same minerals found in the chondrite host. The false color allows us to determine the chemistry of the minerals we’re looking at.

Now that we’ve got a handle on a the chemistry of our system and how it possibly formed, our next task is to deduce how long it took to cool. We know that it sustained its heat for a time sufficient enough to generate brand new crystals. What we don’t know is how long it took to cool. Something we’re looking at is the high aluminum content in our pyroxenes. The amount we’re dealing with tells us that we had some disequilibrium conditions occurring right as our melted rock solidified. This will be important for telling us the maximum temperature of our melt and the temperature at which it cooled.

Picture2

This is the same false color BSE image, but at a higher magnification. The bright green minerals are our aluminous pyroxenes. The large greyish blue clast in the upper left is a pyroxene clast and the one mineral right above it is a feldspar. The large triangular mineral in the lower left corner is an olivine clast. The bright pink core is unmelted iron rich olivine and the dark pink rims are melted and recrystallized magnesium rich rims. 

This summer I’ll be working to address these issues through the McNair program. This is a research scholarship that will essentially pay me to do full time research this summer and present it at the McNair Symposium. If I’m so inclined (and I am) I can also submit it to the McNair Undergraduate Journal for publication. Then in the Fall I’ll be working with both my advisers on a journal publication about my meteorite. I’m also looking to do a poster for the AGU conference in December. If I’m feeling particularly courageous, maybe an oral presentation, too.

Further goodness I’ve been involved in:

A glimpse into my home away from home, the Cascadia Meteorite Lab.

A couple months ago a student in PSU’s film department, Emily Yurek, decided to do a short documentary on the meteorite lab. In the documentary she interviews Dick Pugh, our awesome out-reach coordinator, where he talks about the lab and why we study meteorites. Don’t tell him I said this, but I have a lot of respect for Dick. He knows a lot about meteorites and is enthusiastic in sharing his knowledge. I was also interviewed and got to talk a bit about the work that I’ve been involved in.

I think the documentary turned out well and I’m grateful to Emily for making the lab a little more visible to the public. My hope is that this video will generate more publicity for our lab, and hopefully, donations. We have over 700 samples to study and not enough monetary resources to do the work. All the work is voluntary and done out of a love for the science of meteoritics. And since we are a publicly funded lab, we’re here to answer the public’s questions about meteorites and even look at rocks if you suspect you might have a meteorite.

Anyways, watch the documentary and, if you feel like chipping in even $5, click here. Every donation goes towards a lab that makes possible original research for undergraduates (such as myself) and graduates alike.

Fireball spotted over Russia

Some pretty stunning footage is coming out of Russia of a possible fireball. I’m saying possible because some news outlets are also claiming that the Russians shot the thing down while in mid-flight. While I don’t doubt that a fireball was spotted over Russian skies, I do doubt the Russians ability to shoot it down. Such a task would require that the Russians knew of its entry well before it entered the earth’s atmosphere and produced an explosion. My feeling is that anything of that size would have been found by more agencies than just the Russian military. I’m gonna follow this pretty closely and see what comes of it all. Until then enjoy the video’s of the fireball and the accompanying explosion.

And the explosion…

 

Phil Plait, the Bad Astronomer, has put up an excellent preliminary article about the Russian fireball.

I’ll continue to add links and updates as they come through. Exciting stuff!

Meteorite Monday: So you think you have a meteorite, part 2.

Part of my responsibilities at the meteorite lab is to handle the e-mails we receive concerning meteorite inquiries. These come in on a nearly daily basis and I can easily receive dozens of requests in a week. I don’t mind answering the e-mails as I consider it an integral part of the outreach that we do as a lab. And if I can teach people about what to look for in a meteorite (or meteorwrong in most cases), then all the better. Generally speaking people are pretty good at following our guidelines for e-mailing us: namely, send us a small amount of high resolution photos. We prefer quality over quantity. As I ranted earlier on Twitter, I occasionally receive e-mails with 25+ photos and it’s a temptation to just delete them and move on.

The sad truth is that the vast majority of people that contact me don’t have meteorites. I would love nothing more than to say “yes you have a meteorite!” to everyone that contacts me. Unfortunately, reality says that earth rocks are far more common than space rocks, but with the added challenge that they all look nearly the same. Take for example this one:

Possible meteorite?

Possible meteorite?

Either it has a fusion crust or it’s a weathering patina. And those indentions are either reglamglypts or weathering features. This is one of the few e-mails I’ve received where I had to stop and examine the picture more closely. Generally speaking I get these sort of pictures:

Definite "meteorwrong"

Definite “meteorwrong”

This rock has a shape that is indicative of being in a fluvial setting. Meteorites are not round and, as a general rule, do not contain vesicles. More importantly, meteorites don’t survive long in a fluvial setting and erode away faster than your typical river sediment.

Some of the worst offenders are slag. This is the byproduct of metal production and is routinely confused for being an iron meteorite. Sometimes slag isn’t even magnetic which just completely rules it out as a meteorite.

A faux-iron meteorite.

A faux-iron meteorite.

My favorite meteorwrongs are scoria. I don’t even need to look at the picture for long to know that it’s not a meteorite.

No. No. and No.

No. No. and No.

Could I be wrong in my visual assessments? Of course. Identifying meteorites via photo alone is like trying to distinguish between chocolate chip cookies and raisin cookies at a distance. It all looks the same until you’ve bitten into it and was sorely disappointed by the presence of raisins instead of chocolate. Yes, I have trust issues from such experiences, but that’s besides the point. I may not know with certainty what type of rock you have, but I know just enough to determine if it’s from space or not. And if I happen to be wrong, then all the better!

*for part 1, click here*

Meteorite Monday: A new edition to my family of space rocks

Today’s Meteorite Monday is a special one to me for two reasons: 1) I get to formally introduce my brand new meteorite and 2) this is the first time I’m updating my blog from WordPress’s mobile app. I love technology!

I posted pictures of my new jewel on Facebook, Twitter and G+ already, but I thought it appropriate to share it on the blog, too. Especially since I haven’t updated in a while.

Here she is, Northwest Africa 7109:

20120917-103258.jpg

This gorgeous specimen was purchased at our fund raiser on Saturday. It was actually bought by a good friend of mine, Dave, and he gave it to me because I was smitten by it when I first saw it. Not only did I get a new meteorite, but the lab got a portion of the sale to apply to our research. So I wanna give a big thanks to Dave for that! Also, big thanks to those that either donated directly to the lab or purchased meteorites. Your contributions are greatly appreciated and further the exciting science we do in our lab.

The particular meteorite I was gifted is an L5. The L refers to a low metal content and the 5 refers to a relatively high degree of thermal metamorphism. In spite of that, some chondrules are still visible. That nice big broken one in the center is a good example. The piece is pretty well weathered as can be seen from it’s rust colored appearance. I believe the dark colored patches are the result of shock blackening, but that’s just a guess.

I fell in love with this sample because it’s a great teaching resource. It contains all the hallmarks of a meteorite: metal flecks, some shock features and, most importantly, chondrules. It’s the type of meteorite that I’m not afraid to break out of it’s case and let people touch and examine. And that’s incredibly important when getting people excited about meteoritics and science in general.

The Cascadia Meteorite Lab Fund Raiser 2012

I talk a lot about my work in the meteorite lab. My time here has taken what could have been a cookie cutter geology undergrad experience and turned into something far more educational and worth while. It would be one the biggest understatements of my life if I said I didn’t feel some sort of connection and debt to the lab.

And it’s for this reason I want to get the word out about our annual fund-raiser. Every year for the past six years, CML has had a get together and fund raiser. The purpose of this event is two-fold: to give donors a chance to see how we utilize their money and to further raise funds for our operations. CML is part of the Portland State geology department, but we are financially independent of the school. We are given space and office equipment, but any funds for thin section production and analytic work (SEM,EMP, etc..) comes out of CML’s own funds. We do have an endowment of sorts, but we’re only able to access the interest generated. It’s enough for a project or two, but not much else. For all other work we have to raise money or apply for grants.

The fund raiser serves as a meet and greet where space science and meteorite enthusiasts can talk with one another and tour our lab. There’s a potluck for food and we also have a silent auction on meteorites. Or if you prefer to not bid on a space rock, you can buy one outright from a couple of the dealers that normally come to the fundraiser. All purchases, regardless if it’s from the silent auction or bought from a dealer, benefit the lab either directly or indirectly.

This year is going to be a little different. Brother Guy Consolmagno, also known as the Vatican Astronomer, will be speaking about the Vatican’s meteorite collection. Some might scratch their heads at the idea of someone being a scientist and working for the Catholic church, but Brother Guy is legitimate. Check out this interview to see what he’s all about.

Brother Guy Consolmagno posing in front of a rather handsome collection of meteorites. (Picture from Wikipedia. Courtesy of Kevin Nickerson)

Here are the details for the event:

  • When- September 15th from 2-6 P.M. Brother Guy’s talk starts around 3 P.M.
  • Where- Cramer Hall at Portland State University. The pot luck will probably occur in the Geology Office in room 17. Look for the trail of space nerds and you’ll be set.
  • Who- Everyone is invited. It doesn’t matter if you’ve donated to the Lab or not.

Something I greatly want to emphasize is that this is a fund-raiser. Even if you can only chip in five or ten bucks to the general CML fund, please do so. Every little bit helps and we’re not looking to get hundreds of dollars out of individuals. Although we certainly won’t say no if someone is feeling extra generous. And if you can’t make it to the event, but would like to donate, this link will take you to this years newsletter. It not only talks about all the awesome work we do, but also has a form with instructions on how to donate to the lab.  You can donate to either the E.F. Lange Endowment or the Cascadia Meteorite Lab Fund. If you do decide to donate, please consider giving to the CML fund as we’ll be able to use all of the donation instead of just the interest generated from it.

For more information about the event visit our website.

When space rocks hit the big time

If you’re like me and involved in planetary sciences or meteorites, or just a space-buff in general, this week must have seen like mana from whatever god you may or not believe in. There were a couple big news items that made this week all the more fun to be involved in space science.

First up: Planetary Resources. In my opinion, this has been the biggest news of the week because of the players involved. When you hear about an asteroid mining company being funded by the tech titans at Google (among other wealthy people) and R&D being headed by engineers from NASA/JPL, you can be sure that Planetary Resources doesn’t plan on being the one-hit wonder of the nascent private space sector.

With that being said, I’m cautiously optimistic that this entire venture will succeed. Do I think they’ll find all this platinum that they’re looking for? Not entirely. When I look at meteorites (which come from asteroids) I don’t do a modal abundance of platinum; I’m looking at iron/nickel abundance. Since they’re not looking at the meteorites themselves, I can only assume that they’re using spectral analysis to determine how much platinum is available in a given asteroid. While this is a fairly useful tool, spectral analysis has a tendency to give false readings based on the degree of space weathering an object has suffered.

Now, with all that being said, I still think it’s a great idea and we’ll hopefully see many technological advances come out of this. And who knows- this sort of venture may lead to other job opportunities for those such as myself that study meteorites, and by extension, the asteroids from which they come.

The second cool piece of news: brand new meteorites from the California fireball from last Sunday!

The new Sutter's Mill Meteorite. Aren't they pretty? (Image from NASA Lunar Science Institute)

I don’t know much about these meteorites yet. However, from the picture I can say that it’s a carbonaceous chondrite with some CAI’s (calcium aluminium inclusions). Those would be the white specks found scattered in the body of the meteorite. Carbonaceous chondrites tend to be on the rare side in our collections, so it’s always nice when we’re able to find more samples to augment our current crop of CC’s. Even more exciting is that these little beauties will possibly tell us more about the origins of solar system than what our collection of meteorites tell us now.

Meteorite Monday: The Holiday Edition

At last nights Skeptics in the Pub a very good friend of mine, Karla, gave me an unexpected gift: a small piece of a pallasite. These meteorites are what I like to call space rock bling and I actually wrote a post about them with the same title. Pallasites are a stony-iron meteorite that have a nickel iron body (or matrix) and are studded with olivine crystals. These meteorites are thought to represent the core/mantle boundary of a differentiated planetesimal that was impacted by another object and broke apart. The iron-nickel matrix is from the core and the olivine crystals are from the mantle. The pieces became incorporated during the impact much in the same way that you work chocolate chips into dough.

This is a piece of the Esquel pallasite from Argentina. It's considered one of the most beautiful due to its large olivine crystals. (Image from Wikipedia)

Mine is labeled as the Bela Pallasite, Russia, but I don’t have much information beyond that. Pallasites discovered in Russia include the Omolon, Pallosovka, and the Krasnojarsk. There was also one found Belarus called the Brahin. I’m not sure which of those mine could be from, but it’s one of the nicest gifts I’ve received in a long time. So, with that I want to say a big thank you to Karla! She made my evening with this piece of cosmic debris and also gave me the inspiration for today’s Meteorite Monday.

My own piece of pallasite! The 2nd piece in the middle has a somewhat visible olivine crystal in it. Bike key for scale.

Meteorite Monday: Space Rocks, an encore edition

I’ve decided to take a quick break from my finals studies and put together a quick Meteorite Monday. This post is one that I wrote back in June 2010 when this blog was hosted on Tumblr. It was my first meteorite themed post and one that I transferred over when I made the leap to WordPress. It’s definitely not my best, but I think it’s interesting to see how my writing has evolved over the past year. While I wouldn’t say my writing is anything special, I do feel like it’s come a long way since then.

Enjoy the repost!

This summer I get to do my very first independent research project. I’ll be helping one of my geology professors finish classifying a meteorite with the use of an electron microprobe. This is my first time doing such a project and as such I have a lot to learn. But that’s the exciting part of doing science: the continual learning process. So, as such I figured it was time for me to learn about meteorites. Or meteors. Or meteoroids. Each name means something different. And according to my instructor, the classification has been changing lately. So, in my efforts to learn the basics about these ancient pieces of space debris, I will be posting what I’ve learned in my blog. To start, those confusing names.

It turns out the terms meteor, meteorite and meteoroide are not interchangeable. They seem to refer to the phases of change space debris goes through as it enters the earth’s atmosphere. This rock can come from the moon, comets, asteroids or even other rocky planets (most notably Alan Hills 84001 from Mars- that deserves a post of it’s own). Some of it can be left over material from the formation of the solar system, almost 4.5 billions years old. While their origins differ they pretty much go through the same process upon encountering the earth’s atmosphere.

The difference between the three names used to be simple. The flash of light produced by the entering debris was a meteor. Any chunks of rock that broke off were the meteoroids. And any piece that didn’t disintegrate in the earth’s atmosphere and made it’s way to the surface was a meteorite.

However, a paper recently published in Meteoritics & Planetary Science by Alan E. Rubin and Jeffrey N. Grossman proposed a complete overhaul of the definitions. They suggest that a meteoroid becomes a “10 micrometer to 1 meter sized natural object traveling through interplanetary space”. A meteorite is a natural object that is larger than 10 micrometers whose parent was any rocky celestial body. The meteorite had to travel under it’s own natural means with enough velocity to escape the gravitational pull of its parent body. It then has to hit something that is larger than itself, natural or artificial, and survive the impact. What is most interesting is that the meteorite doesn’t have to hit a foreign object. If it hits the surface of it’s parent body, it’s still considered a meteorite*.

So, those are the differences between the terms. I think in the next post about meteorites, I’ll cover the classification system. And as a side note, this is my first time writing about anything of this nature. In the very unlikely chance that someone from academia (or anyone at all) reads this, please be kind with criticism. I’ll happily accept feedback if done in a professional manner.