Meteorite Identification Page
6 )Is the rock magnetic and when a magnet is suspended on a string and brought near to it, is it attracted?
Nearly all meteorites have iron-nickel and some are completely iron-nickel. Except for the very rare iron free meteorites, almost all meteorites will mutually be attracted to, or by a magnet. But not all magnets are like, as today's "supermagnets" will attract almost any rock that has even a small amount of iron minerals. Iron is one of the most common terrestrial elements. Therefore in testing rocks that are suspected to be meteoric, it is suggested that a standard iron magnet as opposed to a "rare earth" magnet be used. A positive magnetic result alone does not indicate a meteorite, but when correlated with other critera narrows the possibility of the sample being or not being a meteorite.
7 )Did you actually see the rock hit the ground?
Often I receive rocks that the finder swears they saw strike the ground. The finders are adamant that the fireball plunged to the ground.
"I saw a meteor flaming all the way to the ground last night and when I went out to look for it, I found this in the spot where it hit" they often say.
A fireball (bolide) was observed, but if anyone saw it burning all the way to the ground (horizon) it was actually many, many hundreds of miles away. The terminus of such events occurs between 15 to 20 miles above the earth, and at that point the "burning" phase often ends with huge explosion, or simply fades out. But if it hit burning all the way to the ground an explosion akin to that of an atomic bomb would surely be the result. The amount of kinetic energy in meteoroid traveling at 7 to 30 or more miles per second is enormous, and fortunately our planet's thick blanket of air protects its surface (and us) from constant bombardment. If this were not so then even a small pea sized rock or chunk of iron hitting the ground at 30 miles per second would explode with the force of a 500 lb bomb and create a crater yards in diameter. Our world would look like the moon if it were not for our atmosphere burning these cosmic interlopers up.
But such events do occur.
For if a large enough object enters the atmosphere, and then reaches the ground with even a fraction of its cosmic velocity, cratering can be extensive. The Sikhote Alin event in the former USSR on Feb 12, 1947 was the last such recorded cratering event.
Fortunately, crater forming events are rare in terms of the scale of human history, and most meteorites that fall to earth simply plunge to the earth's surface innocuously. Freshly fallen specimens are usually found beneath the track of observed fireballs, or directly under the point over the ground where the fireball terminated.
Freshly fallen meteorites, whether small or large will show (unless fragmented) some amount of fusion crust. This crust is usually dark gray to black, but in some instances such as in the rare Cumberland Falls Meteorite, Norton County Meteorite, and the Pena Blanca Springs Meteorite (observed falls) fusion crust can look like a thin tan to dark brown varnish.
Fusion crust is one of the primary characteristics that one looks for in the process of meteorite identification. Except for very weathered specimens most will have a fusion crust or traces of it, and learning to identify it is important in sorting out meteorites from "meteorwrongs"
Often after a fireball event people are excited enough to go out and look for meteorites, and previously fallen ones not related to the event that sparked one to search are sometimes found. Thus it pays to search after a major fireball sighting.
So, if your rock meets most if not all of these meteorite identification points, then there is a fair chance that it is genuine. You should then send it, or at least a grape to walnut sized piece of it (20 - 30 grams) to a university that specializes in meteorites or to an authority, such as myself.
I offer meteorite identification services at no cost, other than a small sample. Should your rock prove to be a meteorite, then I will evaluate it and give you an idea as to what it is worth.
However, should you submit a sample, include with it a clearly written e-mail address or a stamped-self-addressed-envelope so that I can return a reply. And PLEASE, DO NOT SEND ANY ROCK SAMPLES REGISTERED OR CERTIFIED ! I will not receive these, and they will be sent back unopened. If you wish to have a test sample returned please include sufficient postage for me to do so. Also, should you send e-mail photo attachments of your specimen please insure that the files are in JPEG format and no larger than 75K in size.
American Meteorite Survey
P. O. Box 1003
Flagstaff, AZ 86002
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