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 <azizhab...@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 Widmanstätten" 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> > > > > ______________________________________________ > Visit the Archives at > http://www.meteoritecentral.com/mailing-list-archives.html > Meteorite-list mailing list > Meteorite-list@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@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list