[meteorite-list] Meteorite Yields Carbon Crystals Harder Than Diamond

[Steve Dunklee]

I may be wrong but seems to me the pressures of entering the atmosphere did not create the diamonds unless they were in the crust. A supernova on the other hand is a more likely source of them.
cheers
Steve

--- On Thu, 2/4/10, STARSANDSCOPES at aol.com <STARSANDSCOPES at aol.com> wrote:

> From: STARSANDSCOPES at aol.com <STARSANDSCOPES at aol.com>
> Subject: Re: [meteorite-list] Meteorite Yields Carbon Crystals Harder Than Diamond
> To: meteorite-list at meteoritecentral.com
> Date: Thursday, February 4, 2010, 2:24 AM
> 
> Hi list,  This is off topic (sort of)  to 
> this very interesting post but 
> it 
> does mention graphite and 
> diamonds.   
> 
> I have shared this observation before and every  time
> I have mentioned it  
> I 
> have been taken wrong!  Has any else  noticed how
> the graphite inclusions  
> in the fossil EL3, NWA 2828, 2965,  Al Haggounia 001
> etc. fool an 
> electronic  
> diamond tester?
> 
> Now  this is the part I have been taken wrong on, I'm
> not  saying I have  
> found testable size diamonds but rather the graphite will
> set off  an  
> electronic diamond tester!  Those testers operate on
> thermal   
> conductivity.  
> 
> I can take my optical scopes to 2000X but that is 
> no  help in this stuff.
> 
> I have tried similar inclusions in other 
> meteorites  and nothing.  Is the 
> inclusion made of nano diamonds  or just a
> material  that is as thermally 
> conductive as  diamonds?   Which ever,
> it is  interesting!
> 
> Tom  Phillips
> 
> In a message dated 2/3/2010 6:23:57 P.M. Mountain Standard
> Time,  baalke
> @zagami.jpl.nasa.gov  writes:
> 
> http://www.physorg.com/news184402061.html 
>    
> 
> Meteorite yields carbon crystals harder than diamond
> by Lin  Edwards
> physorg.com
> February 3, 2010 
> 
> (PhysOrg.com) -- Two new  types of ultra-hard carbon
> crystals have been
> found by researchers  investigating the ureilite class
> Haverö meteorite
> that crashed to Earth in  Finland in 1971. Ureilite
> meteorites are
> carbon-rich and known to contain  graphite and
> diamonds.
> 
> The super-hard diamonds were created when graphite  in
> the meteorite
> experienced the intense heat and pressure of entering
> the  Earth's 
> atmosphere and crashing into the ground. The graphite
> layers would  
> have been heated and shocked enough to create bonds between
> them, in  
> much the same way as humans manufacture
> diamonds.
> 
> The new carbon  crystals were too small to test for
> precise hardness but
> they are known to be  harder than normal diamonds
> because the researchers
> found them by using a  diamond paste to polish a slice
> of the meteorite.
> The crystals were raised  more than 10 µm above the
> polished surface,
> which meant they were harder than  the diamonds in the
> polishing paste.
> The researchers had seen carbon crystals  that
> resisted the diamond
> polishing in one direction before, but the new 
> crystals were unaffected
> when polished in every direction.
> 
> The  scientists then used an array of mineralogical
> instruments,
> including  microscopy, spectroscopy and
> energy-dispersive X-rays among
> others, to study  the structure of the crystals. This
> allowed them to
> identify them as  representing two new carbon
> polymorphs or diamond
> polytypes.
> 
> One is an  ultra-hard rhombohedral carbon polymorph
> similar to diamond,
> while the other  is a 21R diamond polytype ultra-hard
> diamond. The
> existence of ultra-hard  diamonds had been predicted
> decades ago, but
> they have never before been  found in nature. The
> novel form consists of
> fused graphite sheets similar to  artificial diamond.
> 
> Professor Tristan Ferroir, leader of the research 
> team from the
> Université de Lyon in France, said the discovery was 
> accidental, but
> they had thought an examination of the meteorite would
> "lead  to new
> findings on the carbon system."
> 
> Professor Ferroir said there is  currently no way to
> compare the
> structure of the new crystals to boron  nitride and
> lonsdaleite, the 
> artificially manufactured ultra-hard diamonds,  but
> the findings help 
> scientists gain a better understanding of carbon 
> polymorphs and give 
> them new materials to investigate and perhaps 
> synthesize. They also 
> show the carbon system is more complex than
> previously  thought.
> 
> The findings on the new diamond were published in the
> Earth  and
> Planetary Science Letters journal on February 15.
> 
> More  information:*  http://dx.doi.org/10.1016/j.epsl.2009.12.015
> ______________________________________________
> Visit  the Archives at  
> http://www.meteoritecentral.com/mailing-list-archives.html
> Meteorite-list  mailing  list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list   
> ______________________________________________
> Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>