[meteorite-list] Nickel free metal in Meteorites

From: cdtucson at cox.net <*cdtucson_at_meteoritecentral.com*> Date: Fri, 26 Mar 2010 15:23:12 -0400 Message-ID: <20100326152312.O0BN6.47392.imail_at_fed1rmwml4201> · cdtucson_at_meteoritecentral.com

--
Carl or Debbie Esparza
Meteoritemax
---- Alan Rubin <aerubin at ucla.edu> wrote: 
> Low-Ni or Ni-free iron doesn't occur just in some chondrules.  It is also 
> found in impact-melt-rock clasts in ordinary chondrites and at the edges of 
> olivine grains in ureilites.  
SO, THIS MAY EXPLAIN THE KALAHARI FIND OF THIS NICKEL FREE IRON? AND YOUR INPUT IS HIGHLY APPRECIATED HERE. 
These rocks have experienced localized in situ 
> reduction of FeO to metallic Fe as Jeff has pointed out.  But let's look at 
> the context, these low-Ni metallic iron grains are situated within mafic 
> silicate grains that have lots of SiO2, MgO and (away from the reduced 
> metal) FeO.  They are formed in the solid state.  A large iron meteorite 
> isn't situated within a mass of mafic silicate.  You could argue that it 
> broke off, but this also wouldn't work.  Diffusion of oxygen out of the iron 
> mass would probably take longer than the age of the solar system.  
ARE WE TALKING 13 BILLION YEARS HERE (BIG BANG) ? OR 4.6 BILLION?
WHY COULD THIS NOT HAVE OCCURRED AT THE TIME OF BIG BANG .THIS WAS VERY HOT AND QUICK? 
In 
> addition, iron meteorite falls typically contain at least a few inclusions 
> of troilite, schreibersite, cohenite, graphite, etc. that would not form by 
> reduction of FeO.  
RESPECTFULLY, EXACTLY MY POINT. HOW WOULD WE EVER KNOW IF THESE THINGS ARE IN A ROCK THAT WE DISMISS BECAUSE IT HAS NO NICKEL? SEEMS TO ME THERE SHOULD BE A BETTER WAY.
So, I'm afraid that I don't believe that we're missing 
> real meteorites by categorizing Ni-free iron masses as meteor-wrongs.
JUST ASKING. I JUST DON'T GET HOW NICKEL IN AN IRON CAN BE 3 TO 60 PERCENT AND NOT ZERO PERCENT? ESPECIALLY NOW THAT WE KNOW ZERO PERCENT  DOES EXIST IN SPACE. SOMETHING DIFFERENT MIGHT BE GOING ON? 
THANK YOU AGAIN FOR YOUR HELP.
CARL
> Alan
> 
> 
> ----- Original Message ----- 
> From: <cdtucson at cox.net>
> To: "Jeff Grossman" <jgrossman at usgs.gov>; "meteoritelist" 
> <meteorite-list at meteoritecentral.com>
> Sent: Friday, March 26, 2010 11:06 AM
> Subject: Re: [meteorite-list] Nickel free metal in Meteorites
> 
> 
> > Jeff,
> > Thank you for your well explained points.
> > As I have said many times before, you would make an excellent teacher as 
> > your answers always stimulate more thoughts.
> > On that note. you acknowledge that nickel free metal does exist but, from 
> > reduced metal and is very small. With all due respect.
> > Isn't size a relative thing?
> > I mean looking at things on our scale the size of Nickel free metal in 
> > chondrules is small. So, doesn't this means it could be bigger?
> > Look no farther than our own planet. We are way different than other 
> > planets.
> > I have been told by Scientists that the earth is so diverse that it makes 
> > identification of meteorites difficult. This because Earth can and does 
> > have so many different types of rocks. And this is just one planet.
> > So, going back to scale. What if this Reducing of Fe O that turns it into 
> > nickel free iron happens to be really big? Say the scale more like Artares 
> > which makes Earth look like a grain of sand?
> > Based on our current method of weeding out meteorwrongs we may never know 
> > if really big reduction occurs because as part of the weeding process we 
> > eliminate all metal objects that do not contain nickel. And this reduction 
> > process as you say is a known fact.
> > I see more abstracts based on theory than on nickel free iron facts.
> > Another size scale dilemma is also acknowledged in meteorites. They say 
> > ( tongue in cheek) this is either a very large inclusion and the rest of 
> > the meteorite is missing. Or this is the whole thing. This is the case 
> > with irons. Sometimes the iron is nearly pure and other times it is mixed 
> > with silicates as in meso's. But again the point is that these small bits 
> > of nickel free iron could be big but we will never know.
> > It seems to me if we paid more attention to morphology and find location 
> > and less on nickel content (as a must) that we would discover an iron 
> > without nickel. Maybe not as big as Hoba but not as small as what was 
> > found in HAH 237 CBb either. I believe this nickel free iron was also 
> > found in one of the Kalahari Lunar's. Is that from a chondrule also?
> > This particular meteorite HAH 237 is the one they used recently to reset 
> > the date of our solar system but not important enough to open our eyes to 
> > the lack of nickel in bigger meteorites.
> > I don't get it?
> > I understand there is always a story. "This thing fell through the roof" 
> > Okay, does it look man made? Does it have serial numbers on it? Is it 
> > identifiable as an object of any kind like a piece of a tree shredder 
> > blade? If these answers are no then maybe just maybe it did fall from the 
> > sky? (NJ meteorite).
> > In this example it was determined to be possible space junk and yet nobody 
> > bothered to show which space object it could have come from. This object 
> > would have had a significant amount of not only monetary value but 
> > scientific as well. What was this stainless steel chunk of metal doing up 
> > in space?
> > Why would NASA have misplaced such a strange piece of stainless steel? The 
> > science was dropped but, it came from somewhere. We may never know from 
> > where though. We dropped the ball on NJ and we may be dropping balls every 
> > day from a lack of nickel. Heaven forbid we find the first large nickel 
> > free iron! Obviously it would be rare but, there are known ungrouped irons 
> > that are equally rare.
> > Just another question.
> > Carl
> >
> >
> > --
> > Carl or Debbie Esparza
> > Meteoritemax
> >
> >
> > ---- Jeff Grossman <jgrossman at usgs.gov> wrote:
> >> Ni-free metal occurs within chondrules that have experienced reduction
> >> during melting.  These chondrules were originally mostly free of metal
> >> and therefore free of Ni, but contained oxidized iron (FeO) in the
> >> silicate minerals.  During reduction, the FeO was converted into Fe
> >> metal (if the reducing agent was H2, then you'd also make H2O; if it was
> >> C then you'd make CO/CO2).  The pure Fe metal that is made can manifest
> >> itself as "dusty metal" grains within olivine crystals, or sometimes can
> >> coalesce into larger Fe metal particles in the chondrule.
> >>
> >> The thing about this is, it is a local effect within a few chondrules.
> >> Most of the metal in the chondrite is still Ni-bearing.  There is no
> >> easy way to make large masses of this pure Fe metal, such as would form
> >> iron meteorites, because any process that would segregate metal, would
> >> segregate all of it, not just these strange particles.
> >>
> >> Jeff
> >>
> >> On 2010-03-25 5:59 PM, cdtucson at cox.net wrote:
> >> > List,
> >> > During recent research into CBb chondrites I stumbled upon an article 
> >> > from 2007 with references from Rubin  that shows an image of a CC 
> >> > chondrite with nickel free metal.
> >> > How is this possible?
> >> > In past conversations with Scientists when I have asked why do iron 
> >> > meteorites always have to have nickel. The typical response is that 
> >> > they not only have to have nickel but, it has to have a few percent of 
> >> > nickel and not just PPM's of it. In explanation of this as I recall, 
> >> > I've always been told the reason  that meteoritic iron always has to 
> >> > have Nickel is because in nature there is no way to separate the two 
> >> > elements.
> >> > If that is true then how is it that in this case we do in fact have 
> >> > meteoritic metal without nickel? somehow they got separated.
> >> > Unless this analysis is wrong does this not teach us that yes in fact 
> >> > there can and does exist meteoritic iron devoid of nickel. And 
> >> > therefore there not only could be Iron meteorites without nickel 
> >> > but,this ups the odds that there in fact are meteorites without nickel.
> >> > Please see attached abstract. Back scattered images Figure 2 at the 
> >> > fifth page from the top of the article. It says;
> >> > "D. Close up of a CC Chondrule texture. Radiating unidentified minerals 
> >> > and Nickel free metal (met) are set up in a silica-rich matrix."
> >> >
> >> > http://www2.mnhn.fr/hdt205/leme/doc/2007%20Gounelle%20et%20al.%20EPSL.pdf
> >> >
> >> > Thanks Carl
> >> >
> >> > --
> >> > Carl or Debbie Esparza
> >> > Meteoritemax
> >> > ______________________________________________
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> >> >
> >> >
> >>
> >>
> >> -- 
> >> Dr. Jeffrey N. Grossman       phone: (703) 648-6184
> >> US Geological Survey          fax:   (703) 648-6383
> >> 954 National Center
> >> Reston, VA 20192, USA
> >>
> >>
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