Adventures in Science

Posts tagged ‘meteorite identification’

Is this rock from outer space?

We have had this rock for three to four years.

Here you can see our rock sticking to a powerful rare earth magnet that we have on the fridge.

We found this rock with a metal detector in our neighborhood in suburban Chicago about three or four years ago. We have been having fun arguing over whether it is a meteorite ever since.                                                   

Fortunately for us, a new T.V. series called Meteorite Men started on the Science Channel a year and a half ago. The show follows two meteorite hunters, Geoff Notkin and Steve Arnold, as they go on expeditions to suspected or known meteorite impact sites. The show is always an adventure with Geoff and Steve suffering freezing cold, deadly heat, threat of rattlesnakes or unexploded bombs on a military base as seen in a recent episode.

The Meteorite Men designed many pieces of their equipment themselves. They invented a way to make giant metal detectors to drag behind their truck or ATV to cover more ground. They have rare earth magnets attached to sticks that attract small meteorites or fragments. In a recent episode, Orange County Choppers constructed the ultimate meteorite hunting ATV for the Meteorite Men complete with GPS, winch, laptop clamps, metal detectors and many more features. Sweeeet!

Here’s an excerpt from that episode with the bike!

Let’s not forget the science. The show is all about looking for rocks from outer space that have fallen to Earth. The Meteorite Men have been studying space rocks for years and are really good at spotting meteorites but sometimes—like our rock attached to the fridge– they are just not sure and they consult an expert meteorite scientist to identify a find. The expert carefully follows a series of steps and performs tests on the rock. If the rock fails the tests—it is not a meteorite.

We contacted the Meteorite Men a few months ago about our possible meteorite. We asked them for a series of tests that we could perform at home to test our rock. They told us that everything we need to know about meteorite identification is on their web site here:

So we followed the link and started to read and check out our rock.


“Attraction to a magnet.”  

As you can see from the picture of our rock it can be suspended above the ground with a rare earth magnet. However!  It falls off very easily. Hmm.

“Weight. Meteorites are dense; they will feel heavier than Earth rocks.”

Our rock only feels slightly heavier than a normal rock. Not sure.

“Fusion crust. Recently fallen meteorites will exhibit fusion crust. This is a thin black rind, sometimes shiny, sometimes matte black, which is acquired during burning in the atmosphere. A freshly fallen stone meteorite will look much like a charcoal briquette.  Even stone meteorites that have been on the Earth for a long time usually retain some fusion crust and almost always appear much darker than ordinary rocks.”

Our rock does not appear to have a fusion crust.

“Surface features. Meteorites, especially irons, often acquire “regmaglypts” (thumbprints) caused when their surface melts during flight. Stone meteorites sometimes display regmaglypts too, but they are not as well defined as in irons. Meteorites, particularly irons, may also show angular features such as points and ridges, and also flowlines which are caused by melting.”

Our rock doesn’t look like it has any flowlines. It has some jagged areas, but that could be from regular breakage. Our rock doesn’t have regmaglypts. This doesn’t look good for our rock, does it?

“Metallic flakes. Nearly all stone meteorites contain small, bright metallic flakes. These are tiny pieces of extra-terrestrial iron and nickel. You can usually see them after slicing off a small piece, or removing a corner with a bench grinder.”

We didn’t do this test because we don’t have a bench grinder.

Chondrules. Small, colorful, grain like spheres which occur in most stone meteorites, hence the name of these meteorites—chondrites.  Chondrites are the most common type of meteorite. Chondrules are not found in earth rocks.”

Our rock has a grainy texture on the surface, but we think we would need to cut it open to know for sure if the grains were chondrules. We haven’t done that because we don’t have a bench grinder.

Rust or patina. Meteorites which have been on the Earth for a long time will likely start to rust, or – in dry desert environments – acquire a “patina” caused by oxidation. The natural patina of irons is often yellow/ochre, red, or orange.

Yes. Our rock has a slight ochre patina. We washed most of it off when we wet the rock to see the surface grain.

TESTS-How to determine if you have a genuine meteorite

“Visual Inspection. Does your rock exhibit any of the characteristics discussed above?”

Our rock is magnetic, slightly heavier than usual, has small grains, and an ochre patina. It does not have a fusion crust, regmaglypts, or flowlines. We don’t see any shiny metal flakes on the surface and don’t have a bench grinder to look inside for metal flakes.

“The Magnet Test. Please remember, a meteorite will stick easily to a good magnet. If your rock does not adhere to a powerful magnet you almost certainly do not have a meteorite. There are many Earth rocks that also stick to magnets, so if your specimen adheres to a magnet it is not automatically a meteorite, but it’s a step in the right direction.”

Our rock can be suspended by a magnet, but it falls off easily.

“The Streak Test. Iron oxides like hematite and magnetite are the Earth rocks most frequently mistaken for meteorites. They are moderately heavy (not nearly as heavy as iron meteorites) and appear metallic in composition.   Some specimens will stick to a magnet. If you think you have an iron meteorite, here’s an easy test you can perform at home: Take your rock sample and scrape it against the coarse (unglazed) face of a white bathroom tile, just like you were drawing on a blackboard with a piece of chalk. If your rock leaves a reddish or rust-colored streak on the tile it is likely hematite. If it leaves a dark gray streak it is likely magnetite. This test only works on iron meteorites (not stones). A genuine iron meteorite will typically leave NO STREAK, or possibly a grayish mark. Please note that the streak test only work on iron meteorites.”

We drew on a white bathroom tile with some force with our rock and got a very faint gray line.

“The Nickel Test. Most meteorites contain a significant percentage of nickel and iron. Naturally occurring Earth rocks do not, so if your specimen tests positive for nickel it may be a meteorite. Kits that test for nickel can be purchased via the internet, or you can take your rock to a lab that assays (tests) for various mineral components.”

 We haven’t done this test yet. We need to order a kit.

Here is a video showing more tips on how to identify a possible meteorite via the Meteorite Times Magazine.

“…but the cold hard truth, is less than one percent, one percent! is actually going to be a meteorite.”

At this point, we still don’t know for sure if we have a meteorite or a meteor-wrong.  It is most likely that we have an Earth rock, perhaps a piece of magnetite, and didn’t do the scratch test correctly. In the near future we will do the nickel test and then the Window Test as described in the video above. If we are still uncertain, then we will send our rock to a meteorite expert for a definite answer.