[meteorite-list] Popular Site Sheds Light on Meteorites
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Feb 2 17:11:50 2006
Popular site sheds light on meteorites
Do two meteorwrongs make one meteorite?
By Tony Fitzpatrick
Washington University in St. Louis
February 2, 2006
The mysterious orb you find in your backyard that wasn't
there just the day before has to be a meteorite, right?
Wrong. Overwhelmingly the chances are it's a meteorwrong, says Randy
Korotev, Ph.D., research associate professor of earth and planetary
sciences in Arts & Sciences at Washington University in St. Louis. He
says that 998 out of 1,000 meteorites are from asteroids, one out of
1,000 is from the Moon, and one out of 1,000 is from Mars. Of the
hundreds of meteorites that have been found in the United States, none
has been a lunar meteorite, and only one has been a Mars meteorite.
Korotev is a geochemist whose specialty is analyzing the chemistry of
Moon rocks, whether they have been gathered from the Apollo missions or
collected as meteorites from Antarctica or north Africa or other areas
of the world. In recent years, he's become the go-to guy for anybody -
researcher, amateur or professional meteorite collector - who thinks he
might have discovered a lunar meteorite because of a Web site he started
about 10 years ago that deals in great detail with lunar meteorites
Randy Korotev, research associate professor of earth and planetary
science, examines fragments of the Sikhote-Alin iron meteorite that fell
in Siberia in 1947. The sample is the real McCoy, but Korotev regularly
receives samples from meteorite enthusiasts that are wrong McKongs.
Mistakenly identifed meteorites have the quaint moniker of meteorwrongs.
Korotev intended for the site to serve his colleagues and the interested
public, and it is as good an educational site on the topic to be found
anywhere. With the advent of very intelligent search engines, an
aggressive, though little known profession of meteorite dealers - a
lunar meteorite retails from $1,000 a gram to $40,000 a gram - and
hobbyists, Korotev's site began drawing questions from the public about
the veracity of their findings. Some people make appointments to see him
and other Washington University geologist colleagues, but the vast
majority e-mail pictures of their findings to get their answers. While
he didn't keep count of all the contacts he received in the early years,
last year alone he received 900 meteorite queries.
"I felt obliged to answer people's questions and in the process of doing
so, found that I was saying the same thing over and over again," Korotev
explained. "Now, I like to build Web sites and I like photography, so I
came up with the idea of a Web site that could explain both verbally and
visually that your sample is not a meteorite because. . . There are
scores of reasons."
More lucrative than baseball card collecting
"A Photo Gallery of Meteorwrongs"
showcases more than 100 objects misidentified as meteorites. Click on
the photo and a caption comes up alongside the object explaining why the
rocks probably are not meteorites and suggesting what it most likely is
and why. The site provides criteria for recognizing space objects. For
instance, freshly fallen meteorites will have a fusion crust, a glassy
coating that forms on the object during descent. Meteorites also usually
are not angular because during their descent protuberances tend to be
ablated away coming through the atmosphere.
Korotev said there is a growing body of meteorite collectors who, like
stamp or baseball card collectors, are seeking samples of every known
lunar or Martian meteorite documented - that's only between 35 and 40
lunar meteorites. Also, people seek meteorite samples for novelties.
"I've had two young men tell me they want some grams of a lunar
meteorite for their fiance's engagement ring," he said. "My reaction is:
Lunar meteorites are not that attractive, get her a diamond. Besides
they were formed on a planet that doesn't have water, which means that
they're unstable in water, and that's not the sort of thing you want to
put in a ring if your fiance ever wants to wash her hands."
Korotev said that lunar rocks are depleted in volatile elements and
compared to Earth rocks they are low in sodium, potassium, and rubidium,
though high in chromium. There are about 12 different chemical
signatures that indicate a lunar source. Martian meteorites share some
of the same features as lunar ones, except that Martian meteorites are
never rich in feldspar, like most lunar meteorites.
Often, Korotev and his colleagues can do simple, quick tests to
determine if a rock has meteorite potential. If a rock has layers,
strike it - to have layers, gravity is needed. If the rock has low
density, it can't be a meteorite, and he can determine this with a quick
Still, people want him to confirm that what they have is a meteorite.
"I've heard this over and over again," Korotev said. "'I heard a thump
and went outside and found this rock that wasn't here yesterday.' I
can't help noticing that every single rock that people show me or send
me a picture of that 'wasn't here yesterday' is just about the size of a
hardball. More than likely, it was chucked into the yard by some
Korotev said the public can purchase very small samples of legitimate
lunar or Martian meteorites on E-Bay. Big samples of "regular" '
asteroidal - meteorites also can be purchased, and there are museums,
and dealers who can confirm or deny meteorite designation, and a
laboratory in northern Arizona that, for a fee, will do a complete
petrographic - analysis of thin sections of the sample under a
microscope - analysis of rock samples to determine if they are
meteorites. He has the site up to help people and to engage them in
science, and he gets a wide range of responses.
"I had a fellow ask: Do two meteorwrongs make a meteorite?" he said.
"I've had wonderful conversations with schoolchildren in the Phillipines
and housewives in Scotland, but there are some people who are so
convinced that they have a meteorite that they end up not liking me. I
have a place on the site that suggests that before sending to me, read
some of the responses I've gotten from people who don't accept our
conclusions. There are some pretty outspoken people who think that I'm
an idiot. The truth is, it appears human nature just doesn't like to
accept the easy explanation."
Received on Thu 02 Feb 2006 05:10:10 PM PST