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Re: Suggestions for cleaning an Allende meteorite

Hi Bill,

As another teacher, I would like to ask a couple of questions.  First, are
the students really going to handle the specimen?  If so, and the reason
for using it is to "hold bits of outerspace," I would suggest a small iron
such as Odessa, Canon Diablo, Sikhote-Alin, or Mundrabilla.  For other
reasons thought, the Allende is a good choice because of its pedigree.  It
is a fall, a rare class of C chondrite, it is abundantly available because
of the unusually large size of the fall, it is the most studied meteorite
ever, it contains material older than the earth, inclusions within it
closely matche the composition of our sun, it's fall produced the largest
strewnfield in the world, and it is pictured in the Sept. 86 National
Geographic and the April, 1981 issue of National History. Unfortunately, it
is not a durable meteorite.

As for the dirt, you could carefully pick off pieces with a pin-tip.  If
the specimen is quite dirty, it may be a fairly recent find.  Therefor, you
might want to leave some of the dirt on the specimen.  Why?  Well because
it will more closely show what an actual field-found meteorite looks like.
I showed a group of students several meteorite slices once, and a comment
one student offered sticks in my mind.  She said, "I never knew meteorites
were so flat!"  If all the student ever sees are a cleaned and polished
specimens, than that is what they expect to see in nature.  However,
Allende is quite terrestrial-looking anyway.  The dirt can also give clues
as to where it fell.  When meteorites are brought to light by the finder,
the dirt is noted by the researcher.  There have been forgeries where
people claimed the specimen was a new find, but the soil profile on (or in
cracks in) the meteorite did not match the location the finder claimed.
Some meteorites, such as Millbillillie are known for their stained
appearance from the soil they sat on.  This is also science.  Sometimes,
our haste to pretty-up the specimen removes some of it's study value (such
as with painted invertebrate fossils).

What is the size of the investment?  A 15 gram specimen of Allende
(especially a dirty one) should cost about $70-$120 (depending on the
condition and features such as crust, etc.).  If you are paying more, you
might want to look around a little more.

I hope this helped.  Please ask if you have other teaching questions.  I
will be presenting a lecture on Meteorites (including the Allende)  at the
National Science Teacher Association's National Convention in New Orleans
on Friday, April 4.  Any chance you can make it?

Sincerely,

Martin Horejsi
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