[meteorite-list] black diamonds from Canyon Diablo

[STARSANDSCOPES at aol.com]

Hi Laurence,  Great paper!  Thanks for  sharing.

I had a related observation that I thought you might be able to  shed some 
light on.

The EL3 Enstatite NWA 2965 (and a whole lot more  names/numbers) has small 
graphite inclusions.  I notice them most in the  "Blue Phase".  I have found 
that these inclusions fool an electronic  diamond tester.  Other meteorite 
graphite does not (At least what I have  tried).

The grains are to small for me to resolve on my optical  microscope, even 
at a magnification of 1800X.

Is this likely just a fluke  of the testing (Thermal conductivity), or are 
there likely to be micro diamonds  in the material at a level sufficient to 
fool the tester?

The inclusions  are soft and can be easily gouged out with a metal tool.

Thanks,   Tom Phillips


In a message dated 5/2/2009 3:53:06 P.M. Mountain  Daylight Time, 
lgarvie at cox.net writes:
For those who are interested, my  colleague and I recently worked on  
the black diamonds from the Canyon  Diablo meteorite. The abstract can  
be downloaded   at

www.lpi.usra.edu/meetings/lpsc2009/pdf/1346.pdf

In summary,  they are not pure diamond but a combination of diamond,  
lonsdaleite  (hexagonal diamond), and graphite. We also found areas  
that were  neither diamond or  lonsdaleite.



Laurence

-----------------------------------------------------------
Laurence  A.J. Garvie
Collections Manager
Center for Meteorite Studies
School of  Earth and Space Exploration
Arizona State University
Tempe
AZ  85287-1404
USA

phone: 480 965 3361
fax: 480 965 8102
email:  lgarvie at asu.edu

Weblinks:
School of Earth and Space Exploration:   http://sese.asu.edu/
Center for Meteorite Studies:  http://meteorites.asu.edu/

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