[meteorite-list] Analysis Wanted

[Randy Korotev]

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@frontiernet.net/>www.bakers5acres at frontiernet.net

Thanks, Jake
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