We have, over the years, been sent many rocks and photographs
of rocks that finders suspect to be meteorites. Some of them
we have examined up close, and a few we have analyzed for mineralogy
or chemical
composition. For most, however, we have only seen photographs.
It is impossible to identify a meteorite from a photograph. Often,
however, we can say “This is almost certainly not a meteorite”
by looking at a photograph. Unfortunately, we usually cannot say with
much certainty what kind of rock it actually is by looking at a photograph.
The tongue-in-cheek term for a rock that is not a meteorite is a meteorwrong.
We present here a collection of photographs that people have
sent us, posted on the Internet and called to our attention, or that we
have taken ourselves of rocks that people have sent or brought to us.
For most of them we can say “This is almost certainly not a meteorite.”
For a few, we’re not sure. For each photo, we provide a short
explanation of why we think it is not a meteorite. We might
be wrong. To make it more interesting, we include a few photos of real
meteorites for comparison.
Notice: We reserve the right to include here (1) photos
that you send us, (2) photos that we take ourselves of rocks that you
send us, or (3) photos that you call to our attention that are posted
on the Internet if you ask our opinion about whether we think the rock
or photo is that of a meteorite. This is a university; we learn
from each other.
Click on a thumbnail photo below to see a specific photo. To
see the whole collection in order, just keep clicking on the next
link.
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Some considerations: Most
(~99%) meteorites found by amateurs are ordinary
chondrites, irons, and stony irons because (1) these are the
most common kinds of meteorites that fall from the sky and (2) such
meteorites are often easy to spot because they look different from
“ordinary” rocks, even to an amateur. For example,
most chondrites and all irons and stony irons contain iron metal
and are, therefore, magnetic - they will
attract a compass needle. They are also a bit denser
(heavier for their size) than most terrestrial (Earth) rocks.
About 3% of stony meteorites are achondrites
such as howardites, eucrites, diogenites, aubrites, ureilites,
lunar
meteorites, and martian meteorites. Most achondrites contain little
or no metal (<1%) and are not
magnetic. All strongly resemble Earth rocks.
Put another way, many kinds of earth rocks “look like”
the rarest meteorites. If an achondrite does not have a fusion
crust (because it’s worn off or it’s a piece from
the interior of a large meteorite), it is impossible to recognize
it as a meteorite without doing expensive and time-consuming chemical,
isotopic, and mineralogical analyses. All the martian meteorites,
for example, are rock types that are common on earth (basalts,
peridotites,
pyroxenites, dunites).
Many of the people who have sent us rocks
and photos have done so because of our web site on lunar
meteorites. Thus, many of the photos in the collection
above really don’t look anything like “normal”
meteorites. A few resemble lunar meteorites. Again,
however, many terrestrial rocks, particularly sedimentary
rocks and some volcaniclastic rocks, superficially “look like”
the brecciated lunar
meteorites.
Your chance of finding a real meteorite is very low. For example,
there have been only about 22 found
in Missouri and 9 found
in Illinois in the past 200 years.
Less than 1 in 1000 of all known meteorites are from the Moon
(same
for
Mars). Thus,
your chance of finding a rare type of meteorite is extremely
low.
Bottom Line:
If you have a rock that has no fusion crust and it looks like
a
terrestrial
rock,
it
is almost certainly not a meteorite. Meteorite dealers and scientists
aren’t going to be interested in examining, studying,
or analyzing it.
Other Meteorwrong
and Meteorite Identification Sites
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Many thanks to Bob Osburn, Karla Kuebler,
Ryan Zeigler, Bob Dymek, Brad Jolliff, and Elton
for examining or analyzing many of the the rocks and photos depicted here.
This web site has been featured in the following media
Yahoo! Picks - 3 November 2005
Science NetWatch- 9 December 2005
Washington
University News & Information - February 2, 2006
Popular Science FYI, April, 2006 (p. 90)
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