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Author Topic: How can I tell if an iron-rich meteorite is real?  (Read 17307 times)

Offline RD

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Re: How can I tell if an iron-rich meteorite is real?
« Reply #25 on: 20/04/2013 12:47:08 »
Professional opinion ,
J.B - University of Texas 1971, Geology

real



The picture shows a poorly treated meteorite.  The saw used to cut it introduced  unwanted artifacts and failed to produce the Widmanstätten pattern that is shown as tapered dull bodies.

Q. What is the  concrete-grey layer between the rusty-outer and the shiny-interior ?
A. Clue in the question : concrete, ( they should have added something to the concrete to make that rusty-coloured too , although even then the crust/rind is too thick for an iron meteorite  ).     


  Take a trip to a rock shop, look at saws.  Then to nearest university geology dept. Let them keep a piece and you'll be pleased

Skinner also submitted the low-resolution image below which is allegedly a second cut of the same "find"  ...



It's an artifact : the painted-on tiger-stripes are a poor imitation of the Widmanstätten pattern : the markings predominantly run in one direction and there are only two shades of grey, whereas the real Widmanstätten pattern does not predominantly run in one direction, has more than two shades of grey, and exclusively consists of ruler-straight lines.

Professional opinion ,
J.B - University of Texas 1971, Geology

The production of fake meteorites and fake fossils as boomed since the advent of t'internet (ebay) : over time they've got better at faking them.
« Last Edit: 20/04/2013 14:12:19 by RD »
 

Offline JimBob

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Re: How can I tell if an iron-rich meteorite is real?
« Reply #26 on: 20/04/2013 22:44:27 »
grey outer layer is called an ablation rind
« Last Edit: 20/04/2013 22:49:12 by JimBob »
 

Offline RD

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Re: How can I tell if an iron-rich meteorite is real?
« Reply #27 on: 20/04/2013 23:52:05 »
grey outer layer is called an ablation rind

Stony meteorites can have a thick crust like an over-baked loaf ...


http://curator.jsc.nasa.gov/antmet/amn/amnfeb95/petdes.htm

but not the iron ones as iron has a lower melting point than stone so the outer layer
of an iron meteorite melts-off rather than accumulating a thick crust. 

Skinners creation is an contradictory composite ...
It is iron but has it has a thick crust like a stony meteorite.
It has a thick crust and yet something resembling the Widmanstätten pattern is visible on the outer surface.
Photos "mmm-1.jpg" and "m-2.jpg" shows a couple of chondrule-like bumps on the surface,
and yet the section does not show the inclusion of any chondrules : just 100% shiny metal.
It lacks regmaglypts , true of some stony meteorites, but is allegedly an iron meteorite which should have many regmaglypts.

[ We're in danger of giving Skinner tips on how to create a better fake ]
« Last Edit: 21/04/2013 07:52:52 by RD »
 

Offline Bored chemist

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Re: How can I tell if an iron-rich meteorite is real?
« Reply #28 on: 21/04/2013 10:21:36 »
I think the best advice so far was to take it to the local university's geology department. If they think it looks plausible then you can trade an analysis of it for a slice of it and sell the rest with the university report as "provenance".
They will have the enormous advantage of seeing the real thing, rather than pictures.

The marks on the surface might be a crude attempt at mimicry, or it may have been hit by a plough a few times over the years.

Since the surfaces we see are not ground, polished and etched, it's likely that any features are cutting marks and "rust". As far as I can tell they are useless in terms of proving or disproving the object's identity as a meteorite.
 

Offline JimBob

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Re: How can I tell if an iron-rich meteorite is real?
« Reply #29 on: 21/04/2013 23:31:45 »
This is posted as ''... iron-rich meteorite"  not iron meteorite.

Does it matter if I have done the same with other samples when, and since, I was in university?
« Last Edit: 21/04/2013 23:33:36 by JimBob »
 

Offline CliffordK

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Re: How can I tell if an iron-rich meteorite is real?
« Reply #30 on: 22/04/2013 08:58:39 »
This is posted as ''... iron-rich meteorite"  not iron meteorite.

The metallic color, and blue/yellow/brown colors in the cut piece, rust on the outside, and reportedly a magnet strongly sticks to it, all indicates that it is likely mostly iron.

There are a few inclusions or impurities visible in the photos of the slices.

Anyway, I don't think one can judge the authenticity of the sample without better preparation of the slices, and a better history of how, where, and when the piece was found.
 

Offline jutas

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Re: How can I tell if an iron-rich meteorite is real?
« Reply #31 on: 20/11/2013 00:25:15 »
Howdy,
As a meteorite collector of ~15 years, hunter, etc., I thought I might make an account to chime in. 

The pictured specimen does not appear to be an iron meteorite.  Folks on here made some fair points, but most arguments were somewhat misguided, and I would like to take the opportunity to clarify some things.

1) Most (not all) iron meteorites display a Thomson structure when etched with acid.  A fine example of this is Santiago Papasquiero; a granular ungrouped iron:

newbielink:http://www.lpi.usra.edu/meteor/index.php?code=23169 [nonactive]

That said, the vast majority of iron meteorites will not look like this when etched.  Most (but not all) display a Thomson structure (several links in previous messages).  Fine, call it a Widmanstatten pattern if you want, but Widmanstatten's not the one who discovered it. 

And, I must add; most mad-made iron etches to show a similar granular pattern.  It's the very rare meteorite -- but very common man-made relic -- that exhibits a pattern like the one shown in the images. 

2) Why are you people drawing lines along saw marks in the cut face of the object in question?  And why are you drawing on chisel marks on the outside of it?  Comparing the exposed structure of an Antarctic iron that has been ice-blasted for hundreds of thousands of years to the shaley exterior of an American iron that wouldn't weather like that is not productive.  One *almost never* sees the internal structure clearly exposed on the outside of a meteorite. 

3) You can clearly see a rusty rind of at least several mm on the exterior of the specimen in question.  That means you *could not* have any fusion crust left; you can be pretty sure of that.  If you've lost ~a centimeter of material, how would the ~1-2mm thick fusion crust still be preserved on the surface?  It's impossible. 

What happens when you take a piece of iron (meteorite or not) and let it sit outside?  It rusts.  Oxide is not fusion crust by default.  The obvious lack of flow lines and scaly nature of the surface tells us that this object is not covered by a fusion crust. 

4) The iron's actual texture.  It is granular and semi-porous.  I know of a few granular iron meteorites (see link above for an example).  I also know of a few irons that have similar patchy dark inclusions/areas:

newbielink:http://www.lpi.usra.edu/meteor/get_original_photo.php?recno=5641164 [nonactive]

That said, I do not know of any iron meteorites (out of the currently known ~1,100) that have both a granular structure *and* odd black inclusions as can be seen in your specimen. 

It could be a meteorite; I would get it tested.  But I would not bet on it.  People have made a lot of weird meteorite look-alikes in the past few hundred years.  Trust me; you see things like this all the time.  Occasionally, they're meteorites.  But, *almost* never when they look like that on the inside.

Send the end to UCLA.  Dr. Wasson would give it a thorough look for free.  Analysis costs 20 grams or 20%, whichever is less.  Though for larger specimens, he usually asks for a bit more for UCLA's collection.  The analysis costs UCLA ~$600-800 per iron, so it's fair.
 

Offline jutas

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Re: How can I tell if an iron-rich meteorite is real?
« Reply #32 on: 20/11/2013 00:37:52 »
Oh -- and a few more things I noticed. 

Small irons often don't display any regmaglypts. 

Irons do indeed form fusion crust:

A cute small oriented iron:

newbielink:http://www.meteorite.com/wp-content/uploads/2013/08/flow-lines.jpg [nonactive]

An example showing how the fusion crust can be removed in a desert environment via sand-blasting:

newbielink:http://www.meteorite-recon.com/img_inventar/Ziz%20Eisenmeteoriten%20NWA%20854%20.jpg [nonactive]

The reddish coloration is exposed metallic iron covered with a *very* thin layer of oxide.  The grey areas preserved mostly in the bottoms of the thumb-prints are the remaining fusion crust.  Not much fusion crust left on this one, though its surface has lost nearly no material to oxidation.  The Sahara's great for keeping meteorites fresh. 

Most irons like this one below don't have fusion crust; just an external layer of oxide:

newbielink:http://upload.wikimedia.org/wikipedia/commons/0/09/Barringer_Iron_Meteorite.JPG [nonactive]
 

Offline Ophiolite

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Re: How can I tell if an iron-rich meteorite is real?
« Reply #33 on: 20/11/2013 11:29:01 »
I've read this thread with interest and wish to thank jutas for a well-informed opinion.
 

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Re: How can I tell if an iron-rich meteorite is real?
« Reply #33 on: 20/11/2013 11:29:01 »

 

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