Dear Tom, The reason is rather simple: nickel test is only applicable to iron meteorites. For stony meteorites - about 90% of all meteorites - it would not give clear doubtless results and it even would contaminate the meteorite. In case of iron meteorites, the easiest way to identify the cosmic origin is to etch a blank surface using nitric or hydrochloric acid to see if a Widmanstätten pattern is present. Often - especially in case of medium and coarse octahedrites - one can even see this structure on a cut, untreated surface, because of different mechanical properties of contained kamacite and plessite/taenite. In the rare case, that no Widmanstätten pattern is existant (ataxites or hexahedrites), the nickel test would indeed help to disciminate the cosmic from a terrestrial origin.
Best regards, Jorn Koblitz > -----Ursprüngliche Nachricht----- > Von: Thomas Kingery [mailto:[EMAIL PROTECTED] > Gesendet: Mittwoch, 12. Mai 2004 14:57 > An: [EMAIL PROTECTED] > Betreff: [meteorite-list] Classification > > > I am curious why I have never seen anyone mention that they > at least did > a nickel test on an unclassified meteorite they are selling. I realize > this does not prove it to be a meteorite but does increase the > possibility. > Here in Texas there are a few ranchers and others that state > they found > what they believe to be a meteorite but have never nickel > tested or sent > off to be analyzed > > Tom Kingery > Llano,TX > > ______________________________________________ > Meteorite-list mailing list > [EMAIL PROTECTED] > http://six.pairlist.net/mailman/listinfo/meteorite-list > ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://six.pairlist.net/mailman/listinfo/meteorite-list
