[meteorite-list] golden iron color and Widmanstätten" patterns

From: cdtucson at cox.net <cdtucson_at_meteoritecentral.com>
Date: Thu, 1 Apr 2010 19:43:42 -0400
Message-ID: <20100401194342.W4VIM.313550.imail_at_fed1rmwml33>

Jason,
Nice try but, it seems obvious that you have no idea how classifications work.
If you recall in a recent post by Bernd. It was made perfectly clear that what determines a class has more to do with the O-isotopes than the actual lithology or chemistry of the rock.
Having cleared that up it does leave open the possibility that this is a Winonaite or a meso or pallesite for that matter.
The only way to be sure is to have it classified. And have the O-isotopes checked in order to plot against other meteorites .
But please don't belittle peoples guesses with false facts.
I'm sorry but, it has been established that Winonaites can have very little or a lot of metal and there is no rule that says that the silicates have to be recognized by Jason in order to be there. They may be hiding under the metal. The point is that this has a very unusual look and it helps all of us learn by thinking about it. And it's fun.
I think you saying; [It's a pretty coating of desert varnish on a (probably naturally) sandblasted iron.] is a bit of an oxymoron. How can it have desert varnish if it is wind blown and sand blasted?
Nobody cares who is right here. they are just asking questions and trying to get answers. Your guesses may turn out to be right but, you cannot know that quite yet.
Playing the odds, I like what Bernd thinks.
So, rather than end your opinion with a "conclusion" , why not end it with a question mark like other (nice) people do?
Carl

--
Carl or Debbie Esparza
Meteoritemax
---- Jason Utas <meteoritekid at gmail.com> wrote: 
> Hello All,
> 
> It's a pretty coating of desert varnish on a (probably naturally)
> sandblasted iron.
> 
> A winonaite would look like a stony meteorite.  If it were a
> "metal-rich winonaite," you might as well call it a silicated iron -
> but there are no silicates visible anywhere on its (supposedly wind-)
> polished surface, so it's not a winonaite, that much is obvious.
> The fact that you can see a widmanstatten pattern on the sandblasted
> surface means that we're not looking at a lump of troilite, and the
> suggestion that the coloration could be due to iron sulfide
> is...strange.  Troilite occurs as inclusions within iron meteorites,
> and it's clear that the sandblasted surface exhibits no such
> inclusions.  Don't get me wrong - I see why you might say that, Mike,
> since troilite is a bronze-gold color as well, but...there's none
> there.
> 
> So -
> 
> The coloration is due to a thin layer of desert-varnish-related iron
> oxide that forms on the surface of irons exposed to abrasive desert
> winds (and not your typical temperate or tropical oxidation).
> 
> See here for other examples:
> 
> 
> http://picasaweb.google.com/MeteoriteKid/Irons#5444617684310649778
> 
> 
> http://www.flickr.com/photos/cameteoritefinder/2336572790/
> 
> 
> But note that both of these irons are fresh; where fusion crust has
> spalled off, discolored, wind-polished iron is exposed below the
> surface.
> 
> Many NWA 5549 fragments actually display similar surfaces:
> 
> 
> http://www.encyclopedia-of-meteorites.com/test/49248_8446_2637.jpg
> 
> 
> Aziz's iron looks significantly older, and, as you can see from the
> patches of iron oxide covering lower, protected areas on the polished
> surfaces, it was at one point completely covered in a rind of oxide.
> 
> Again, the complete and utter lack of visible silicate inclusions
> rules out the remotest possibility that it's some sort of a stony iron
> meteorite (with the very vague possibility of its being analogous to
> something like a Brenham or Seymchan pallasite, but those are
> indistinguishable from other iron meteorites, so...it would still be
> an "ordinary" iron).
> 
> Conclusion:
> 
> The once-complete rind of oxide tells us that this is an old iron that
> was at some point buried, or at least was fluvially moved or exposed,
> at which point the upper half of its surface was exposed to arid,
> abrasive conditions.
> 
> It's what appears to be a medium octahedrite from the definition of
> the widmanstatten patter on its surface (large, straight,
> clearly-defined kamacite boundaries rule out coarse or coarsest (see
> Ziz, a coarse octahedrite, for comparison - the grain boundaries are
> visible, but all you see are amorphous-shaped outlines and a general
> orientation due to schreibersite crystals and weathering on a few
> fragments), though this iron could conceivably be a fine octahedrite).
> 
> Regards,
> Jason
> 
> On Thu, Apr 1, 2010 at 2:21 AM, habibi abdelaziz <azizhabibi at yahoo.com> wrote:
> > hey all
> >
> > got some? time now and i? missed meteorite, sorry if i miss any emails or didn't answer;;
> >
> > ok many collectors ask me why? this iron has this golden color,
> > what is the process , that make it looking like that.
> > and why the?Widmanst?tten" patterns is showing on the surface,
> > http://www.flickr.com/photos/azizhabibi/page3/
> > can someone answer please ,as myself i do not know why its golden color,
> > i know i have sold two small cut iron that was looking like gold, i may have photo in my archives.
> >
> > thanks
> > aziz habibi
> >
> > ?habibi aziz
> > box 70 erfoud 52200 morroco
> > phone. 21235576145
> > fax.21235576170</font>
> >
> >
> >
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Received on Thu 01 Apr 2010 07:43:42 PM PDT