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, [email protected] <[email protected]> wrote: > From: [email protected] <[email protected]> > Subject: Re: [meteorite-list] Meteorite Yields Carbon Crystals Harder Than > Diamond > To: [email protected] > 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 > [email protected] > http://six.pairlist.net/mailman/listinfo/meteorite-list > ______________________________________________ > Visit the Archives at > http://www.meteoritecentral.com/mailing-list-archives.html > Meteorite-list mailing list > [email protected] > http://six.pairlist.net/mailman/listinfo/meteorite-list > ______________________________________________ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list [email protected] http://six.pairlist.net/mailman/listinfo/meteorite-list
