[meteorite-list] Analysis Wanted

From: Randy Korotev <korotev_at_meteoritecentral.com>
Date: Tue, 10 Jul 2007 14:29:25 -0500
Message-ID: <200707101929.l6AJT3r25358_at_levee.wustl.edu>

Jake:

If you want a chemical analysis, as opposed to a
petrographic or isotopic analysis, I have been
sending people who contact me with meteorwrongs to Actlabs:

http://www.actlabs.com/home.htm

Have Actlabs do analysis code 4-litho:

http://www.actlabs.com/gg_rock_litho_usa.htm

That service costs $60/sample but there's an
extra charge of $16 for pulverizing the sample
(if you haven't done it). They request 5 grams
of material because it takes a lot of material to
do LOI (loss on ignition), which is a measure of
how much water and CO2 are driven off when the
sample is heated to a high temperature. LOI
isn't needed for meteorite identification, but it
is still useful because when LOI is high, the
sample is probably NOT a meteorite. Actlabs can
do the 4-litho analysis on as little as 0.2 g of
material if you request "no LOI."

Over the past 2 years, I've recieved 37 Actlabs
reports. In each case I've been able to say to
the finder with 99+% certainty (my opinion!)
"This rock does not have the composition of any
known type of meteorite but the composition is
consistent with some kinds terrestrial
rocks." Then I point them toward my page of
meteorite and meteorwrong compositions so they can check themselves:

http://meteorites.wustl.edu/metcomp/index.htm

As I say on that page (big cop-out), I can state
to my satisfaction that a rock is not a meteorite
based on the Actlabs report, but if it's a
terrestrial rock, I can't identify the actual
rock type from the chemical analysis.

If the rock IS a meteorite, it is also true that
the Actlabs report itself would probably not be
sufficient to identify the meteorite
type. Meteorite identification is done mainly by
petrography, and I don't know any place in the U.
S. that routinely does that (well) on a fee basis
for unsolicited samples. (Someone correct me if
I'm wrong.) On the basis of just the chemical
composition, I think that I could not
unambiguously tell an L from an LL chondrite, but
I could tell a lunar meteorite from an
eucrite. With the chemical composition in hand,
it will be a lot easier to get a real meteorite
petrographer to look at your rock. Meteorite typing requires petrography.

I have no personal stake in Actlabs, but the
owner and I have met because we both do neutron
activation analysis. Actlabs does it cheaper and
faster and also uses other techniques to get the
concentrations of 55 chemical
elements. Unfortunately, the 4-litho suite does
not include any PGE (platinum group elements)
except nickel. That's a non-issue when it's a
terrestrial rock, but if the rock is some kind of
chondrite, it's nice to have Ir, Au, etc. For extra $, Actlabs will do PGEs.

Randy Korotev



At 13:04 07-07-07 Saturday, you wrote:
I am looking for a reputable lab that will
analyze an observed and recovered fall. I would
consider paying for analysis if it?s not too
expensive. I need the recommendation for a lab
that will do a complete analysis.

I got ripped off by one lab that did no more than
a visual and magnetic exam and don?t want that to happen again.

I?ve tried several universities but because it is
very low iron and does not pass the metallic and
?magnet? test they by-pass it. It is stony,
loaded with chondrules, has a grey fusion crust,
when sliced the edges along the fusion crust show
a greater density than the interior, it is
extremely dense ? a small football (American not
soccer) sized piece weighs 19 pounds, there are
metallic inclusions and a small circular magnet
will roll slowly toward the specimen.

You can contact me off list and I?ll send
pictures.
<http://www.bakers5acres at frontiernet.net/>www.bakers5acres at frontiernet.net

Thanks, Jake
__



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Received on Tue 10 Jul 2007 03:29:25 PM PDT