I found a meteorite! (Probably not)
Near midnight on Thursday, March 27, 2003, as I was preparing for bed, I noticed a bright flash outside. I did not think more about it at the time, but in the morning I learned it was a small asteroid, weighing between 900–7000 kilograms (1900–15,000 lbs.), that had burst overhead (a bolide) producing the bright light. I also learned that the bolide had exploded above Park Forest, Illinois, about 30 miles south of Chicago; people in this area had not only saw flash but they heard explosions. Even more exciting, hundreds of pieces of the asteroid had survived their entry into the atmosphere, scattering meteorites over a large area. Big pieces, weighing as much as 2.5 kg (5.5 lbs.) crashed through roofs. Almost immediately, meteorite scientists (meteoricists, not meteorologists) from the Field Museum and the University of Chicago collected or obtained as much as possible, hoping to obtain pristine material. But they were joined by a horde of amateur and commercial meteor collectors and dealers looking to find and purchase as much as they could. According to the Chicago Tribune (March 26, 2004), pieces were selling for as much as $20 a gram (about $550 an ounce). Some large pieces were selling for tens of thousands of dollars. One that crashed through the roof of a home sold at auction in 2009 for more than $50,000.
Just like some fossils, meteorites not only have scientific, but also monetary value. And like fossils, there are many other objects that look like meteorites, but are not. And, just like paleontologists, meteoricists and geologists are often brought objects by a member of the public who are certain they have found a meteorite. Unfortunately, the things that are not meteorites (called with tongue-in-cheek “meteorwrongs”) far outnumber those that are actually are. And not everyone is happy to hear that piece of slag they brought in is not worth thousands of dollars. So as a service to the public and to my geologist and meteoricist colleagues, I want to present a quick guide to separating the meteorites from the meteorwrongs.
1. This is a great opportunity to learn about meteorites, other extraterrestrial objects, and geology. Do some background reading on asteroids, meteors, meteorites, and the various kinds of rocks that occur naturally on Earth. Your public library should have some basic books on these subjects, written at a variety of levels. You may see your rock or something very much like it. Pay special attention to the sections on how asteroids form and what happens when they enter our atmosphere. If you prefer looking online, high-quality websites include: Some Meteorite Information from Washington University in St. Louis (this is a great website!), this one from NASA; and from National Geographic (we will return to the first of these in a moment).
2. This is also a good time to visit your local natural history museum. They may have examples of meteorites on display. If you have a local rock shop, they may also help in identification.
3. Investigate the geology of your area. Every state has a geological survey that has made maps and published descriptions of local regions. Knowing what terrestrial rocks are present yours was found will help constrain the identification. For example, your area may be underlain by ancient basalts, an igneous rock that might easily fool you.
4. You might also want to spend some time learning something about the human history of the place where your rock came from. Was there ever an iron foundry or other factory there? Industrial slag is commonly confused with meteorites.
5. If you are still convinced that you have a meteorite, now is the time to check if you have a meteorwrong instead. Look at the photos on this page: https://sites.wustl.edu/meteoritesite/identification/ and click through the link to familiarize yourself with what are and are not meteorites. And read this: https://sites.wustl.edu/meteoritesite/items/some-meteorite-realities/ Then go through the flow chart here: https://sites.wustl.edu/meteoritesite/items/self-test-check-list/. And finally this: What to do if you think you found a meteorite. Like I said, this is a great website!
6. To repeat some of the information on the website:
a. Carefully record where the specimen came from. Include as detailed a geographic description as possible, at least to the level of county or nearest town. This allows a geologist to determine what bedrock is present in the area. It is also proper collection practice; a specimen of unknown geographic origin (“provenance”) is virtually useless.
b. Write a description where the specimen was found. Did you inherit it? Was it loose in a stream bed? Hammered out of a rock formation? Picked out of road gravel? In the middle of a cornfield? It is important to know if the specimen can be directly associated with the bedrock in the area. If possible, photograph the site.
c. Take sharp photographs of the specimen with different lighting and orientations; they should fill the frame. Natural light is best. If possible, take close-ups. Always include a clear scale.
d. Then, and only then, reach out to a professional for their opinion (but make sure you do the steps in [5] first!).
A few more things. Don’t expect an immediate response to an email or letter. Although interacting with the public is integral to what we do, most scientists have full time jobs, with many demands on their time. For the same reason, do not show up unannounced. Send an email first, with the information discussed above. What led you to think it is a meteorite? If the specimen is of interest, you will be invited to make an appointment.
Be prepared to hear that you’ve found something common, that it’s not a meteorite at all, or that it’s not even a natural rock. And please don’t start an argument over this; you asked for a professional opinion, and you received it. If you don’t agree, then feel free to ask elsewhere.
Ethically, a professional will not make an appraisal of monetary value. On the other hand, there is chance that the specimen is of scientific interest. In that case, you may be asked to consider donating the meteorite to a museum collection. If it is really unusual, it may become the subject of a scientific paper!
My new book, Explorers of Deep Time: Paleontologists and the History of Life, can be ordered from Columbia University Press.
