Identifying Meteorites: Differentiating Between Extraterrestrial and Earth Rocks

[1oldman2]

While visiting Wyoming recently I was shown a "rock" that several people have said is a meteorite. My question is how does one identify a meteorite compared to an Earth rock. (Hoping you can help me out here Dave) I have included several photos and I can say it definitely shows signs of high heat and while its not magnetic like "load stone" a compass passed over it will swing the needle around. Any opinions would be greatly appreciated, thanks.

 

[ProfuselyQuarky]

Meteorites have certain properties that nearly all of them share. For example, most meteorites are natural magnets. Also, meteorites (especially the ones with a high % of iron) tend to melt as they fly towards Earth. Once they land, they leave these distinct marks (I believe they’re called regmaglipts** or something like that). A meteorite’s composition includes iron and stone (mostly stone). So, people can also do composition, streak, and density tests. If all these points hit the correct mark (which I’m not aware of; it depends probably), the chances of your rock being a meteorite is pretty good, I suppose.

There are probably more definite tests that I don’t know of so let’s wait for someone else to answer.

**EDIT: Just looked it up. The correct spelling is regmaglypts

 

[ProfuselyQuarky]

The rock in the photo appears looks awfully smooth, though. A meteorite usually looks like this:

Maybe there are different types . . .

 

[1oldman2]

The rock in the photo appears looks awfully smooth, though. I meteorite usually looks like this:
View attachment 99863

Yes, that is how I picture an average meteorite. Have you looked over Daves meteorite section? it seems looks alone aren't much of a qualifier as they have a great variety of appearances. This is complicated by the diverse geology in the area the "rock" was found, let me know your take on things as this thread progresses. Here is Daves site, take a look, pretty cool stuff.
http://www.sydneystormcity.com/

 

[ProfuselyQuarky]

Yes, that is how I picture an average meteorite. Have you looked over Daves meteorite section? it seems looks alone aren't much of a qualifier as they have a great variety of appearances. This is complicated by the diverse geology in the area the "rock" was found, let me know your take on things as this thread progresses. Here is Daves site, take a look, pretty cool stuff.
http://www.sydneystormcity.com/

Yes, I've looked at it before! Isn't it great? Perhaps @davenn would be better to answer the question.

To me, rocks are rocks. And I'd probably be the one fooled if I saw iron pyrite and say that it's gold :P

 

[256bits]

"Shows signs of high heat"
Weathering can give a shiny look to a rock and peculiar features.
My first guess is that it is an iron oxide nodule.

 

[1oldman2]

"Shows signs of high heat"
Weathering can give a shiny look to a rock and peculiar features.
My first guess is that it is an iron oxide nodule.

Thanks, I appreciate the input. Whatever the thing is it has had an interesting existence.

 

[ProfuselyQuarky]

My first guess is that it is an iron oxide nodule.

In other words, not a meteorite after all?

 

[1oldman2]

In other words, not a meteorite after all?

A very distinct probability considering how rare those buggers are, This is the best place I could think of for answers so naturally here I am asking.
(by the way a little less than two hours until Russia launches from their new facility)

 

[256bits]

Thanks, I appreciate the input. Whatever the thing is it has had an interesting existence.

If rocks could only speak. the tales they could tell.

I gave only a first guess as a nay. Doesn't prove anything.
If I had it in my hand that is what would come to mind in the Sherlock Holmes process of elimination and what remains, even if extradinary ( meterorite, since they are rare compared to other rocks ) has to be the truth. One should consider the nays, along with the yays, just to be fair to the rock.

In other words, not a meteorite after all?

Never really said that - appearance can be deceiving one way or the other.
As you stated there are tests to do along the way to identification.

 

[Vanadium 50]

My question is how does one identify a meteorite compared to an Earth rock.

Most identified meteorites are from Antarctica. It's not that more fall there - it's that if you find a rock on top of three miles of ice, chances are it came from the sky.

 

[1oldman2]

Most identified meteorites are from Antarctica. It's not that more fall there - it's that if you find a rock on top of three miles of ice, chances are it came from the sky.

That is what I understand also, very long odds of this being a meteorite but it is a peculiar piece of rock, somewhere between igneous and metamorphic. If it turned out to be a real meteorite it would probably be considered a relatively large one.

 

[davenn]

While visiting Wyoming recently I was shown a "rock" that several people have said is a meteorite. My question is how does one identify a meteorite compared to an Earth rock. (Hoping you can help me out here Dave) I have included several photos and I can say it definitely shows signs of high heat and while its not magnetic like "load stone" a compass passed over it will swing the needle around. Any opinions would be greatly appreciated, thanks. View attachment 99862

hmmm a little tricky

channelled streaks like that are not uncommon in meteorites. I am not going to say "definitely is or isn't

the closest similar I could find is this meteorite sample ...

There is a possibility that it is an iron nodule and I am leaning a little more in that direction

Dave

 

[1oldman2]

There is a possibility that it is an iron nodule and I am leaning a little more in that direction

Thanks, could you tell me what tests, chemical analysis or whatever that would be used to determine its true nature ? The area of central Wyoming (near Thermopolis) where it was found is a real "geological jigsaw puzzle" so that's not much of a clue, however odds favor nodule over meteorite.
Cheers and thanks again.

 

[Hoophy]

From what I hear if you scratch a meteorite candidate with a white bathroom ceramic tile and it leaves grey or brown streaks on the rough side (the side of the tile that should face the wall/floor) it is some sort of iron ore. If it leaves no streak it may be a meteorite. This test of course only works if the candidate is in fact magnetic. I heard this from an acquaintance and it may be entirely false. I would assume that you would need to perform a multitude of different tests to be sure. Do you have personal access to the specimen?

 

[davenn]

From what I hear if you scratch a meteorite candidate with a white bathroom ceramic tile and it leaves grey or brown streaks on the rough side (the side of the tile that should face the wall/floor) it is some sort of iron ore. If it leaves no streak it may be a meteorite.

not a good test as many meteorites are of nickel / iron composition and are magnetic as well ( or at least attracted to a magnet)

The area of central Wyoming (near Thermopolis) where it was found is a real "geological jigsaw puzzle" so that's not much of a clue, however odds favor nodule over meteorite.

I don't know the geology of that area ... if it has any significant sedimentary deposits related to it, mudstones, clays etc
Then iron nodules can be readily found in suchD

 

[1oldman2]

if it has any significant sedimentary deposits related to it, mudstones, clays etc

http://wsgs.wyo.gov/

http://www.space.com/33037-king-tut-blade-made-of-meteorite.html

 

[ebos]

I would check the geology of the area it was found to confirm or not if it was an iron nodule. However, I'm voting for the meteorite. Looks like whatever was in those channels may have melted out on the way down. Of course, what do I know. Get it checked at the nearest university.

 

[davenn]

I would check the geology of the area it was found to confirm or not if it was an iron nodule.

yes, that's what I already commented on

I don't know the geology of that area ... if it has any significant sedimentary deposits related to it, mudstones, clays etc
Then iron nodules can be readily found in such

and going by what I found in the link posted

http://wsgs.wyo.gov/

it gives good credence to an iron nodule because of the number of large sedimentary basins
in the region
without knowing more about the types of sediments, I cannot comment further to if they would support iron nodule formation

Looks like whatever was in those channels may have melted out on the way down.

that is a possibility and one I also commented on much earlier in the thread

but it is also possible that they are fractures caused by the formation of the nodules in the ground ...
eg .. freeze/thaw fractures caused by moisture within the nodule
Dave

 

[1oldman2]

I'm hoping to get an analysis arranged for some point in July until then it's just a "weird looking rock", I will definitely post the results when I get it figured out. In reading up on meteorites, I understand that the ratios of Iron to nickle (as well as other elements) is a determining factor in whether or not the sample is "extra-terrestrial" however I couldn't find any practical way to visually make an identification without lab testing samples.
The area the "rock" was found is a conglomeration of just about every geological feature that can be imagined, including plenty of sedimentary and Tertiary fill, not to mention the "worlds largest hot spring". Thanks and I'll keep in touch with the results when I get them.

 

[Ophiolite]

My initial reaction was iron nodule. On reflection I was still thinking iron nodule. After looking on line for nodule images I remained 95% in favour of it being an iron nodule. This site is an especially useful one: http://meteorites.wustl.edu/id/concretions.htm

 

[1oldman2]

http://meteorites.wustl.edu/id/concretions.htm

Thanks for the link, interesting reading, I've been looking for a site such as this.

 

[Fervent Freyja]

Accidental or intended byproduct from an asphalt plant? I'd take it to one of those and ask them! If it were a sample they made in their lab, then the grooves could indicate it had been tested by a machine, which is a requirement before paving any street. I imagine those samples would be just as crudely put together in the same shape. Just a thought, since they are so very similar.

Refined asphalt/bitumen

 

[davenn]

Accidental or intended byproduct from an asphalt plant? I'd take it to one of those and ask them! If it were a sample they made in their lab, then the grooves could indicate it had been tested by a machine, which is a requirement before paving any street. I imagine those samples would be just as crudely put together in the same shape. Just a thought, since they are so very similar.

I have no idea why you posted this and what it has to do with iron nodules or meteorites ??
it's just side tracking away from the topicDave

 

[1oldman2]

Useful info here!
http://meteorites.wustl.edu/what_to_do.htm
http://meteorites.wustl.edu/id/regmaglypts.htm
http://meteorites.wustl.edu/realities.htm

 

[1oldman2]

I love flowcharts, (especially useful ones) From the site mentioned in previous post.

 

[Hoophy]

"Meteorite Or Meteorwrong?" :D

 

[Fervent Freyja]

I have no idea why you posted this and what it has to do with iron nodules or meteorites ??
it's just side tracking away from the topicDave

Oh, I wasn't aware that Old Man had gotten results back confirming it actually is a meteorite or iron nodule or that you have taken over his thread and reestablished the topic.

I made a decent attempt to fully answer his post to the best of my ability at the time (although I'm now on the fence). He made it clear that any opinions were welcome and so far hasn't discounted peoples efforts to answer the thread (like you just did to mine).

 

[davenn]

I love flowcharts, (especially useful ones) From the site mentioned in previous post.

View attachment 102235

of course this chart doesn't include stony meteorites, which are very common

 

[1oldman2]

of course this chart doesn't include stony meteorites, which are very common

I hadn't noticed the "stony meteorite" being omitted, I was to busy looking at what was there to notice what wasn't.
As an update I haven't positively ID'd the rock yet, as it's still at a relatives house in Wyoming and while a "picture may say a thousand words" the testing will wait a bit while I save up the cash for it. Thanks for the input and I'll keep you posted on the results when I get some news. I do plan on submitting photos to the individual mentioned in the flowchart.

 

[256bits]

of course this chart doesn't include stony meteorites, which are very common

I interpret the flowchart as,
Stoney would be on the left hand side, and middle.

If the density is greater than other general rocks, it is probably contains iron, but not noticibly magnetic like an iron meterorite, so not a meterorite.
If a crust and lighter colour, it may be a stony or carbonaceous meteorite.

Top and to the right is iron meterite, which should surely be magnetic.

Of course, density, colour, etc is relative, as is the classification "stony".

 

[davenn]

If the density is greater than other general rocks, it is probably contains iron, but not noticibly magnetic like an iron meterorite, so not a meteorite.

don't forget the relatively common stony-irons

there's 3 main classes
stones, stony-irons and ironsalso just noticed a big mistake in there, see the circled part

DOH ... if some one saw it fall, then it has to be a meteorite !
D

 

[256bits]

don't forget the relatively common stony-irons

Which is somewhere in the middle section, in that mix of lefts, rights, and downs.
He is kinda loose with his boxes and yes's and no's.
There are two boxes asking if it is heavier than other rocks, and dark crust.
I suppose the chart is meant to eliminate rather than confirm identification.

DOH ... if some one saw it fall, then it has to be a meteorite !

I think he is trying to weed out someone 100% thinking a stone that hit the roof of the house has to be a meteorite. Could have been the neighborhood kids throwing rocks. I bet he gets people thinking it must be a meteorite if a rock rolls up to their feet while walking near a cliff face.

 

[davenn]

I suppose the chart is meant to eliminate rather than confirm identification.

almost seems that way huh

I think he is trying to weed out someone 100% thinking a stone that hit the roof of the house has to be a meteorite. Could have been the neighborhood kids throwing rocks. I bet he gets people thinking it must be a meteorite if a rock rolls up to their feet while walking near a cliff face.

hmmmmmmmmmmmmmmmmmm maybe ... but the normal definition of seeing it fall is seeing the flash in the sky

 

[256bits]

hmmmmmmmmmmmmmmmmmm maybe ... but the normal definition of seeing it fall is seeing the flash in the sky

Too far away to run to keep up with it to see it hit the ground. Superman maybe.

 

[davenn]

Too far away to run to keep up with it to see it hit the ground. Superman maybe.

many many meteorites are recovered after seeing the fall ( the flash across the sky)
I even have 2 friends here in Australia that make major efforts to get a bearing on the fall direction
etc so they can work out the approx. location of the fall then go and see if they can find anything

tis something guys do all over the world

 

[1oldman2]

many many meteorites are recovered after seeing the fall ( the flash across the sky)
I even have 2 friends here in Australia that make major efforts to get a bearing on the fall direction
etc so they can work out the approx. location of the fall then go and see if they can find anything

tis something guys do all over the world

Howdy, I read recently about some guys making a great find at Lake Eyre not long ago using that method, What luck!

 

[1oldman2]

From the site I got the flowchart from.

 

[davenn]

"True lies" ... wasn't that an Arnie movie ?? hahahaha

 

[256bits]

this is worth mentioning,

A statistical study of the rates of meteorite falls (5) suggests approximately 17 meteorites >0.1 kilograms (0.22 pounds) in size fall in Arizona, or an area of equal size, each year. Two to three of these samples weigh >1 kilograms (2.2 pounds) and are about the size of your fist. A meteorite weighing >10 kilograms (22 pounds) falls every 2 to 3 years. Thus, from the turn of the century, approximately 240 meteorites >1 kilograms in size are believed to have fallen in Arizona. Since Father Kino first arrived in the Tucson area (1687), approximately 790 meteorites >1 kilograms in size are believed to have fallen in Arizona. Of this large number of meteorites, only 32 have been recovered, and only 1 of these (the Holbrook http://www.lpi.usra.edu/science/kring/epo_web/meteorites/falls.htmlmeteorite ) was observed to fall (2).

which is the ,
http://www.lpi.usra.edu/
( Lunar and Planet Institute, Houston, Tx )

By Arizona, they mean any surface area the size of Arizona.
Going by that, generally, 1 out of every 32 meteorites collected have been falls.
And as mentioned, luck is part of being at the right place at the right time.

Tracking the meteor path( fireball ) across the sky can give an indication of where it originated in the solar system.

 

[256bits]

Oh, I wasn't aware that Old Man had gotten results back confirming it actually is a meteorite or iron nodule or that you have taken over his thread and reestablished the topic.

I made a decent attempt to fully answer his post to the best of my ability at the time (although I'm now on the fence). He made it clear that any opinions were welcome and so far hasn't discounted peoples efforts to answer the thread (like you just did to mine).

I can well imagine that people find a rock, note its odd shape, texture, look and feel, and conclude it has to have come from no where else than from space.

 

[davenn]

I can well imagine that people find a rock, note its odd shape, texture, look and feel, and conclude it has to have come from no where else than from space.

uh huh
I regularly get people coming to me with rocks and asking if they are a meteorites

 

[1oldman2]

I can well imagine that people find a rock, note its odd shape, texture, look and feel, and conclude it has to have come from no where else than from space.

Hi, Odds are extremely good (Astronomically actually) that the rock I opened the thread with will check out to be an iron nodule, I look at it as lottery winning odds, however as they say "someones got to win" so its worth checking out. I guess in the long run (very long run) its true all rocks as well as the rest of Earths elements do actually come from space, all I'm sure of at the moment is its definitely not a piece of bitumen.
An interesting look at reported meteorite finds in the US http://meteorites.wustl.edu/numbers_by_state.htm
Cheers all.

 

[1oldman2]

uh huh
I regularly get people coming to me with rocks and asking if they are a meteorites

Just curious, have any of the rocks people have brought you turned out to be meteorites?

 

[davenn]

Just curious, have any of the rocks people have brought you turned out to be meteorites?

no from memory, there was only one that looked remotely like a meteorite once I finally saw it "in the flesh" but wasnt
the others were easily dismissedDave

 

[Idaho Astro]

If it is, indeed, iron, then the streak test (rubbing it on unglazed porcelain, like the underside of a toilet lid or the back of a porcelain tile) is a pretty strong indicator. If it's terrestrial iron, it will either leave a dark gray streak (magnetite) or a blood red streak (hematite). A meteorite should leave no streak at all (as long as you are rubbing a clean part of it, not any rust that may have formed on the surface after it sat on the ground for years/centuries). So, file a clean spot first, then do your streak.

 

[JoeBrown]

I found something very similar softball sized parts were magnetic and weighed over 3700 grams and took it to the local college geology department and was told by the professor hey wasn't sure but thought it was banded iron. I still think I'll get a second opinion but your pic looks very much like what I found.