[meteorite-list] Geophysics, meteorites, and Electron microscopy-QUESTION

From: Shawn Alan <photophlow_at_meteoritecentral.com>
Date: Wed, 7 Sep 2011 15:47:52 -0700 (PDT)
Message-ID: <1315435672.91147.YahooMailClassic_at_web160116.mail.bf1.yahoo.com>

Hello Carl and Listers

Great post on scanning electron microscope (SEM) process, now does this process also ID the whole classification of the meteorite which is used for classifying meteorite for the Meteoritcal Bulletin database? I know alot of school are discontinuing classifying meteorites is UNM also doing the same?

Question if someone wanted this service to be done on a meteorite, how much would it cost, cause these days money talks and helps everyone out when it comes to classifying meteorites or confirming that the meteorite is the meteorite suggested to be. Also can this process determine the difference between Ensisheim (LL6) and Saint-S?verin (LL6) by the cosmic ray exposure or terrestrial age. These two meteorites look identical and some can fake it. Does SEM also cover that test or is that a different test? Lastly how long does it take for you to classify a new meteorite from start to finish if its a stony meteorite?


Shawn Alan
IMCA 1633
eBaystore
http://shop.ebay.com/photophlow/m.html




[meteorite-list] Geophysics, meteorites, and Electron microscopyCarl Agee agee at unm.edu
Tue Sep 6 12:27:18 EDT 2011


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A scanning electron microscope (SEM) is great for high magnification
images that also contain information about the chemical composition of
the different minerals in meteorites. SEM is also a quick way to do a
qualitative analysis of a sample, say for example, detecting nickel in
iron meteorites with energy dispersive spectroscopy (EDS).

My instrument of choice for definitive ID of stony meteorites is the
electron microprobe. This also has SEM imaging capability. In less the
hour, on a calibrated electron microprobe, I can make a definitive ID,
although unequilbrated chondrites can take more time to narrow down
the possibilities. Some of the key geochemical quantities that help in
categorizing are, Fe/Mn of olivines and pyroxenes, the fayalite and
ferrosilite content of the olivines and pyroxenes, the
anorthite-albite content of plagioclse, and a few other parameters,
plus the percent mineralogy and other textural characteristics.

So for a simple example lunar olivines usually have higher Fe/Mn than
terrestrial basalt olivines. Check out this page's second figure for
an overview of Fe/Mn versus plagioclase content of planetary basalts:
http://www.imca.cc/mars/martian-meteorites.htm

Carl Agee

-- 
Carl B. Agee 
Director and Curator, Institute of Meteoritics 
Professor, Earth and Planetary Sciences 
MSC03 2050 
University of New Mexico 
Albuquerque NM 87131-1126 
Tel: (505) 750-7172 
Fax: (505) 277-3577 
Email: agee at unm.edu 
http://epswww.unm.edu/iom/pers/agee.html 
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Geophysics, meteorites, and Electron microscopy 
Barb and Jake Baker bakers5acres at frontiernet.net 
Tue Sep 6 10:50:46 EDT 2011 
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________________________________ 
Could someone tell me, in Microscopy 101 language: How is an electron 
microscope used in the study of meteorites? Using electron microscopy - 
what differences are apparent between meteorites and terrestrial rocks? For 
instance what are the microscopy differences between lunar basalt and 
terrestrial basalt? 
Thanks 
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Received on Wed 07 Sep 2011 06:47:52 PM PDT