[meteorite-list] "How Do You Know It's A Meteorite"?

[Greg Redfern]

Hello All,

   My answer is very simple - "we don't know until a reputable lab says
so". 

If the questioner has need for further response I am glad to do so by
using some of the techniques described by our esteemed colleagues on
this list. If the individual(s) is rational and not in a lather about
how it is a meteorite regardless and the wealth and fame that is to
follow, this works pretty well.

All the best.

Greg Redfern
NASA JPL Solar System Ambassador
http://www2.jpl.nasa.gov/ambassador/index.html
WHAT'S UP?: THE SPACE PLACE
http://www.wtopnews.com/?sid=600113&nid=421


-----Original Message-----
From: meteorite-list-bounces at meteoritecentral.com
[mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of AL
Mitterling
Sent: Monday, April 07, 2008 3:08 PM
To: meteorite-list at meteoritecentral.com
Cc: Thomas Webb
Subject: Re: [meteorite-list] "How Do You Know It's A Meteorite"?

Hi Thomas,

A response you could give in a friendly way is, why is it that you don't

think it is a meteorite? Then go on with many of the tests that show 
that it is, (because they probably won't truly know what a meteorite 
is), tests positive for nickel (certain classes), has fusion or 
weathered fusion crust, has metal in it (again most classes and most 
specimens found), is irregular in shape, has rounded edges from ablation

through the atmosphere, looks different from the local rocks, interiors 
are gray to dark brown in color, should or may attract a magnet, are 
usually heavier than terrestrial rock (some basalts are about as heavy 
as chondrites, tend to oxidize if they have been exposed to weather for 
very long, usually don't have bubble like cavities (only rare 
specimens), on a grounded edge will sometimes show little round 
spheroids called chondrules (if an ordinary chondrite or carbonaceous), 
meet most of the criteria above but not necessarily all of it.

Such a question is a common laymen's question and it is a good one but 
they are questioning how you know. We know because we have had much more

experience with specimens and identifying them. The average person 
doesn't know because they are not yet educated on how to know. Showing 
many examples of meteorites (I keep it basic because you can confuse 
them with too much variety) and showing them examples of most common 
meteorwrongs is a good start with helping them to know the difference. 
I've found that it takes a lot of practice (months or even a year or 
more) before someone new can begin to identify specimens and you always 
have to keep your eyes open for something totally off the wall that may 
be new!! I.D. comes with some responsibility. If in question send a 
small sample off to a qualified lab that will get back to you when they 
are done. Best!

--AL Mitterling

Thomas Webb wrote:

>Dear List Member,
>I would like to hear your most convincing response to
>the layman's question, "How do you know it's a
>meteorite"?
>My best,
>Thomas
>  
>
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