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Kent10
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Best Etched Meteorites?
      #6066694 - 09/06/13 06:55 PM Attachment (14 downloads)

I have been looking at etched meteorites and was wondering if there is a consensus on the favorite markings or is it completely a personal thing.

For example I really like this one MUONIONALUSTA

Also, I have noticed that some MUONIONALUSTA look better than others. Is it the way the etching is done or is it just that some rocks look better than others. Or is it the lighting in these 2 examples. Thanks, Kent


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Kent10
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Re: Best Etched Meteorites? new [Re: Kent10]
      #6066696 - 09/06/13 06:55 PM Attachment (11 downloads)

2nd one

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Kent10
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Re: Best Etched Meteorites? new [Re: Kent10]
      #6067536 - 09/07/13 10:28 AM Attachment (10 downloads)

Another I like

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Kent10
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Re: Best Etched Meteorites? new [Re: Kent10]
      #6067557 - 09/07/13 10:41 AM

I have been doing more reading and it seems many like the Gibeon (the one above) and the MUONIONALUSTA just like I do. It seems the Gibeon is more stable and less likely to rust than the MUONIONALUSTA. Is the MUONIONALUSTA a real problem? And is the Gibeon problem free or just less likely to rust? Is it the most stable iron?

Thanks.


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Kent10
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Re: Best Etched Meteorites? new [Re: Kent10]
      #6067576 - 09/07/13 10:49 AM

Info I found on etching techniques

Meteorites can be etched in many different ways, some produce lighter etches and some produce darker etches. Generally the darker an etch the less details are visible. Some etchants produce fast results within few minutes, but may burn the surface of a meteorite and cause a somewhat blurry appearance. We have etched many meteorites over the years, in our opinion a lighter but detail- rich etch is preferable over a darker one. Additionally we use a very slow etching technique which brings out much more contrast between the different shades of gray present in a Widmannstätten- pattern, however, instead of a couple of minutes this process lasts up to 1 hour. For us well worth the effort.

http://midnightsunmeteorites.com/en/why-buy-from-us.html


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Kent10
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Re: Best Etched Meteorites? new [Re: Kent10]
      #6067743 - 09/07/13 12:37 PM Attachment (9 downloads)

Initially I didn't particularly like the Taza but I do now. This is my sample. The markings are quite visible in this pic but normally it is difficult to see them. The surface is very reflective. I am wondering if a coating of plastic or something was put on it. Should I be able to feel the grooves of the markings.

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Glassthrower
Vendor - Galactic Stone & Ironworks
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Re: Best Etched Meteorites? new [Re: Kent10]
      #6069233 - 09/08/13 10:32 AM

The two major methods of etching are - nitol and ferric chloride. Nitol is the preferred method, but it is more expensive to purchase and requires more careful handling. Because of this, some preparers will use ferric chloride, which is readily available as a circuit board etchant at places like Radio Shack. It's cheap. And it produces a distinctive etch that is darker and "bolder" than nitol.

However, ferric chloride introduces chlorine into the meteorite and the result is almost always a boatload of stability issues down the road.

BTW, who are/is "Midnight Sun Meteorites"? Just curious, because I have never heard of them until now.


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Kent10
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Re: Best Etched Meteorites? new [Re: Glassthrower]
      #6069245 - 09/08/13 10:39 AM

Thanks for the info, Mike. I have no idea about "Midnight Sun Meteorites". I was just searching for info on etching and that came up.

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lee14
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Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: Kent10]
      #6069258 - 09/08/13 10:45 AM

Gibeons are certainly a very stable iron, they can generally do without a corrosion inhibiting treatment. Muonionalustas have been subjected to a very different environment, and as a result are more weathered, and have absorbed a greater amount of terrestrial contaminants. While they are both fine octahedrites, there is a significant difference in hardness. Gibeons cut very well, while Muons are much tougher and frequently dull a blade after a single cut.

There are two main components that contribute to the appearance of the etched surface. The type of etchant and its strength (concentration), and the final grade of the abrasive used to finish the surface, produce great variation in the contrast. I prefer nitric acid in methanol for etching, and though some recommend ferric chloride, I decline to introduce any additional source of chlorine into a specimen. The final abrasive grade can vary from around 320 grit to a mirror polished surface. The degree of the final grinding or polishing varies from type to type of iron, I find that 320 - 400 grit is appropriate for Campos, 600 for fine octahedrites like Gibeons or Muons, and a high polish to a mirror-like surface works best for Canyon Diablos.

There are differences between specimens of the same variety as well. Heat and/or shock can seriously affect the underlying crystal structure, which will be very apparent after etching. I once cut up a fist sized Gibeon that showed a typical etch most of the way through, and then came to an area of lesser contrast and diminishing bands, and finally a golf ball sized portion that lacked any Widmanstatten pattern at all. Kind of like a self contained ataxite in an otherwise typical specimen.

You generally won't feel the lines of an etch, the surface is affected only a few molecules deep. That's why the type and angle of the lighting can have such a profound effect on the appearance. Some specimens can benefit from a more aggressive etch process though, and enough kamacite is removed to leave the brighter acid resistant taenite or other bright bands unaffected. This is common in Canyon Diablos which require a longer period in the acid solution

Lee


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Kent10
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Re: Best Etched Meteorites? new [Re: lee14]
      #6069266 - 09/08/13 10:48 AM

This is all very interesting for me, Lee. Thanks for explaining all this.

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Glassthrower
Vendor - Galactic Stone & Ironworks
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Reged: 04/07/05

Loc: Oort Cloud 9
Re: Best Etched Meteorites? new [Re: Kent10]
      #6069532 - 09/08/13 01:37 PM

Quote:


Thanks for the info, Mike. I have no idea about "Midnight Sun Meteorites". I was just searching for info on etching and that came up.





I'm glad you mentioned them, because I am always on the lookout for new dealers. This particular dealer is a mystery to me. There is no clue to their identity on their website and their domain name has privacy cloaking. Now the detective work begins in earnest.


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Glassthrower
Vendor - Galactic Stone & Ironworks
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Re: Best Etched Meteorites? new [Re: Glassthrower]
      #6069535 - 09/08/13 01:38 PM

Thanks for the info Lee. If I ever have questions about iron prep, you are on my list of experts.

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lintonius
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Reged: 12/13/05

Loc: south-central Utah
Re: Best Etched Meteorites? new [Re: lee14]
      #6069689 - 09/08/13 02:59 PM Attachment (9 downloads)

I have a few etched Gibeon slices and they vary in appearance. I wonder if Lee, Mike or anyone can tell which technique was used. I have only etched a couple times and I used ferric chloride. It was easy and I got pretty good results. I wish the whole slice looked as good as the part slices, which I'll show first.
Linton

99.0g part slice...


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lintonius
sage


Reged: 12/13/05

Loc: south-central Utah
Re: Best Etched Meteorites? new [Re: lintonius]
      #6069697 - 09/08/13 03:02 PM Attachment (8 downloads)

136.1g part slice...

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lintonius
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Reged: 12/13/05

Loc: south-central Utah
Re: Best Etched Meteorites? new [Re: lintonius]
      #6069712 - 09/08/13 03:08 PM Attachment (11 downloads)

Now compare that with this 778.0g whole slice...
I'm thinking about re-etching this on myself, but I'd hate end up with a worse result. Perhaps I should try it on the back. Any thoughts?


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lee14
super member


Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: lintonius]
      #6069717 - 09/08/13 03:09 PM

Glad to be of service Kent. You ask insightful questions and your photography is superb!

Lee


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Kent10
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Re: Best Etched Meteorites? new [Re: lee14]
      #6069727 - 09/08/13 03:14 PM

Thanks Lee. I do like photography and own some good equipment but these are pics from the advertisements when I bought them. I think the photo does make a huge difference though. Some represent the meteorite very well perhaps making a piece look better than it really is while others it is difficult to know what it will look like when you receive it. There was one that looked totally different when I got it. I liked it more actually. I tried to take some pics of it myself but I will need to get the tripod out sometime to really do it justice.

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lee14
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Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: lee14]
      #6069774 - 09/08/13 03:39 PM

Lintonius; nice Gibeons slices. I can't tell from looking whether ferric chloride or nitol was used. Ferric chloride leaves a higher contrast etch, but individual stones vary in etch appearance, so only a side by side comparison would help. Gibeons tend to have a very tight surface and lack any significant amount of chlorides to begin with, so the ferric chloride method is probably safer here than with the more corrosion prone varities like Campo, Dronino, Nantan, and Muonionalusta. Still, I would personally avoid it, I have a deep seated fear of chlorine contamination.

The way ferric chloride works is a bit indirect. Through a couple of reactions, HCl (hydrochloric acid) is produced, and that is what does the actual etching. It works more rapidly than nitol and produces a darker, deeper etch. Although I've never tried it, I suspect diluting the ferric chloride solution with distilled water would slow the etching process and give you a little more control.

For a discussion of etching techniques, you may consult appendix D of 'The Cambridge Encylopedia of Meteorites' (Norton) or 'The Meteorite and Tektite Collector's Handbook', (Bagnall; Wilmann-Bell).

Lee


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Kent10
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Re: Best Etched Meteorites? new [Re: lee14]
      #6069793 - 09/08/13 03:50 PM

I also found this interesting to read

http://www.nuggetshooter.ipbhost.com/index.php?showtopic=7933


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lee14
super member


Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: lee14]
      #6069810 - 09/08/13 03:58 PM Attachment (5 downloads)

Ah Kent, I think those Muon slices are probably from the same ebay dealer you referenced previously. I agree with you about the difficulty of imaging a reflective metallic surface, it's a real challenge to get it to actually look 'metallic' and not simply varying shades of gray. Hoping to avoid any vendor issues here I'll simply say I sell on ebay as well and try to use a range of photos that represents a specimen from it's optimal appearance to a more 'casual' average contrast shot. I've got a great camera, but getting a true metallic sheen to show well is still a crapshoot for me. This is a 132 gram Muonionalusta that I had recently.

Edited by lee14 (09/08/13 04:01 PM)


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lee14
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Re: Best Etched Meteorites? new [Re: lee14]
      #6069825 - 09/08/13 04:07 PM Attachment (6 downloads)

and the reverse...

Edited by lee14 (09/08/13 04:10 PM)


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lee14
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Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: lee14]
      #6069852 - 09/08/13 04:23 PM Attachment (6 downloads)

This is a 43 gram Canyon Diablo showing some of that metallic sheen that's so elusive to capture.

Lee

Edited by lee14 (09/08/13 04:26 PM)


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Kent10
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Re: Best Etched Meteorites? new [Re: lee14]
      #6069866 - 09/08/13 04:32 PM

Those are great photos Lee and really show the etch well. Yes that 1st slice in this thread is from jlacroix1 on ebay. The 2nd one is just a picture I found somewhere online for comparison purposes. The 3rd one is a Gibeon from jlacroix1 that I ended up buying. It was not inexpensive but half the price of a Muonionalusta that I was considering. The one at the top of this thread I think was $719 but it was a thick end cut 820 grams.

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lee14
super member


Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: lintonius]
      #6069881 - 09/08/13 04:39 PM

Lintonius- If you want to attempt to re-etch only one face, you can protect the other side with blue painters tape. Butt the seams tightly rather than overlapping, and press the tape firmly onto the surface making sure it's securely adhered at the edges. Sand the surface with 600 grit wet/dry automotive type sandpaper, keeping all the lines straight in one orientation only. The paper fills up quickly, so keep fresh abrasive on the surface. You're trying for a uniform hazy polish. The concentration of your etchant should be such that it takes a couple of minutes for the process to complete, any quicker and it's difficult to control resulting in too dark an etch.

Lee


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Kent10
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Re: Best Etched Meteorites? new [Re: lee14]
      #6069895 - 09/08/13 04:46 PM

Lee--I thought those pics looked familiar and I recalled that I had seen them on ebay. I found your page again and you have some very nice ones. I'll have to keep an eye out. I feel like I am reaching my limit right now though. I have bought more than I thought I would and am really caught up in this. This Canyon Diablo looks interesting with the black marks in it, different than most I think. I like it.

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lee14
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Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: lee14]
      #6069908 - 09/08/13 04:52 PM

Kent- I've never bought any etched material from lacroix, just whole Campos, but it looks like very nice work. At around a dollar a gram it would be very difficult to do better. He's apparently buying an enormous amount of material and getting a nice low starting price. Ten years ago whole Gibeons and Muons could be had for less than 20 cents a gram, and that's not very likely these days. The export of Gibeons has been illegal for a number of years, and that's contributed quite a bit to the desireability of Muons.

Lee


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lee14
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Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: lee14]
      #6069945 - 09/08/13 05:12 PM

I must apologize for my inadequate photographic skills Kent. What appear as black marks are in fact highly reflective and silver colored. They either reflect all the light right back, or in another direction entirely, thus appearing dark. There are a few at the top of the specimen that look silver, the rest are mirror-like as well from the proper angle. Canyon Diablos are a really unique variety to deal with. The appearance can vary from a medium octahedrite (although it's classified as coarse) to an almost featureless gray matte surface after etching. The main mass suffered some really extreme shocking around impact, and this tends to mute or even eliminate the Widmanstatten pattern. In addition there can be a fair amount of carbon in Diablos, often presenting as graphite nodules, which are very desireable to collectors. There can also be an amount of microscopic diamond in the material, either already present before impact, or the formation was exacerbated from the carbon under extreme pressure at impact. These are the most difficult irons I've ever tried to cut, and the only ones that absolutely require a diamond blade.

Lee


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lee14
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Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: lee14]
      #6069956 - 09/08/13 05:22 PM Attachment (7 downloads)

This is an unetched 42 gram Canyon Diablo, I left it at a high polish because I just liked the look. There are a couple of bands near the upper edge; if it was etched, these would remain bright.

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lee14
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Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: lee14]
      #6069968 - 09/08/13 05:31 PM Attachment (7 downloads)

And finally, a 161 gram Canyon Diablo that looks more like a medium octahedrite. The interesting feature of this one though is how impact stress caused the crystal plates to warp and curve, resulting in a really unique Widmanstatten pattern.

Lee

Edited by lee14 (09/08/13 05:33 PM)


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Kent10
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Reged: 05/08/12

Re: Best Etched Meteorites? new [Re: lee14]
      #6070004 - 09/08/13 05:56 PM

Lee--I think your photography is beautiful and I remembered looking at your pieces. It must be difficult to get a picture of just the way it looks in person. I really like that high polish one too. The cracks add to the features. I also like that cubed one you have for sale.

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lee14
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Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: Kent10]
      #6070019 - 09/08/13 06:07 PM Attachment (6 downloads)

Thanks Kent. As when imaging more conventional subjects, I take a lot of exposures and dump most of them. It's certainly an easier task with digital imaging than with film. Just one more pic for now, a 31 gram Mundrabilla. A really unique etch, and a very hard stone. You can see a bit of the crust, it too has a nice reddish patina and is a very stable variety. Seemingly hard to come by these days, their export (Austalia) has been prohibited as well. Lee

Edited by lee14 (09/08/13 06:15 PM)


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Kent10
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Re: Best Etched Meteorites? new [Re: lee14]
      #6070025 - 09/08/13 06:13 PM Attachment (5 downloads)

Oh wow. I like that one. I didn't know they were hard to get. It looks like I have one coming from Germany any day now.

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Kent10
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Re: Best Etched Meteorites? new [Re: Kent10]
      #6070026 - 09/08/13 06:14 PM Attachment (5 downloads)

Other side

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Kent10
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Re: Best Etched Meteorites? new [Re: Kent10]
      #6070036 - 09/08/13 06:19 PM

Ooops. That is a corner Campo del Cielo of yours that I was looking at. Not a cube. There is a difference.

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lee14
super member


Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: Kent10]
      #6070038 - 09/08/13 06:20 PM

Nice! This is another variety that seems to etch best after bringing the surface to a high polish. There are a number of very good German dealers. One I like alot is Gipometeorites (ebay).

Lee


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Kent10
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Re: Best Etched Meteorites? new [Re: lee14]
      #6070074 - 09/08/13 06:46 PM

Lee-- I just bought that corner piece. I really need to be done buying soon . I did tell my wife I was buying several meteorites and she thought I was spending thousands so I do feel better because actually it is just 100's but I think must be going over 1000 easily by now. It is fascinating though.

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Kent10
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Re: Best Etched Meteorites? new [Re: Kent10]
      #6070076 - 09/08/13 06:47 PM

I'll have lots of ebay bucks soon so I'll be able to get a small one for free

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Kent10
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Reged: 05/08/12

Re: Best Etched Meteorites? new [Re: Kent10]
      #6070082 - 09/08/13 06:51 PM

I remember looking at Gipometeorites. He does have some nice slices. I bought some from mirko66 and donnersteine.

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lee14
super member


Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: Kent10]
      #6070222 - 09/08/13 08:41 PM

Yes, Gipometeorites has developed some good sources for his NWA material. I know him personally, although we haven't corresponded in a while. A really nice guy though. Mirko66 I'm familiar with, I think I may have bought from him in the past. Donnersteine is unfamiliar.

Lee


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Kent10
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Re: Best Etched Meteorites? new [Re: lee14]
      #6070235 - 09/08/13 08:53 PM

Donnersteine seems to specialize in GEBEL KAMIL

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lintonius
sage


Reged: 12/13/05

Loc: south-central Utah
Re: Best Etched Meteorites? new [Re: lee14]
      #6070359 - 09/08/13 10:19 PM

Quote:

Lintonius; nice Gibeons slices. I can't tell from looking whether ferric chloride or nitol was used. Ferric chloride leaves a higher contrast etch, but individual stones vary in etch appearance, so only a side by side comparison would help. Gibeons tend to have a very tight surface and lack any significant amount of chlorides to begin with, so the ferric chloride method is probably safer here than with the more corrosion prone varities like Campo, Dronino, Nantan, and Muonionalusta. Still, I would personally avoid it, I have a deep seated fear of chlorine contamination.

The way ferric chloride works is a bit indirect. Through a couple of reactions, HCl (hydrochloric acid) is produced, and that is what does the actual etching. It works more rapidly than nitol and produces a darker, deeper etch. Although I've never tried it, I suspect diluting the ferric chloride solution with distilled water would slow the etching process and give you a little more control.

For a discussion of etching techniques, you may consult appendix D of 'The Cambridge Encylopedia of Meteorites' (Norton) or 'The Meteorite and Tektite Collector's Handbook', (Bagnall; Wilmann-Bell).

Lee




Thank you, Lee. Former Michael Casper pieces.
Interesting info too, though I should do some more homework before making any decisions.
I should start by pulling out Norton's CEofM.
Linton


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lintonius
sage


Reged: 12/13/05

Loc: south-central Utah
Re: Best Etched Meteorites? new [Re: lee14]
      #6070381 - 09/08/13 10:34 PM

Quote:

Lintonius- If you want to attempt to re-etch only one face, you can protect the other side with blue painters tape. Butt the seams tightly rather than overlapping, and press the tape firmly onto the surface making sure it's securely adhered at the edges. Sand the surface with 600 grit wet/dry automotive type sandpaper, keeping all the lines straight in one orientation only. The paper fills up quickly, so keep fresh abrasive on the surface. You're trying for a uniform hazy polish. The concentration of your etchant should be such that it takes a couple of minutes for the process to complete, any quicker and it's difficult to control resulting in too dark an etch.

Lee




Yeah Lee. I might try the back first, so I don't lose the etch I already have. I used a random-orbital sander on prior etchings (long-time woodworker;^). I take it you don't recommend that?
Linton


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lee14
super member


Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: lintonius]
      #6071310 - 09/09/13 01:15 PM

I've actually considered a random-orbital sander (long time woodworker as well), but never actually tried it. I suspect that even the very fine swirls it leaves might be visible in the final etch. I suggested sanding in one direction because the alignment of the crystal plates, especially with fine and medium octahedrites, helps to disguise the visibility of the sanding marks. I finish my pieces first on a stationary belt sander to produce a flat surface, through the sequence of grits, and do the final sanding with a cloth wheel and 'dry' abrasives. Two reasons for this; grit for grit the wheel abrasives do a finer job and leave less distinct lines, and, the cloth wheel will compensate for any surface irregularities and yield a more uniform finish. Of course the foam plate on a random orbital sander might do that as well. I would certainly be interested to hear what kind of results you get.

I got my first large Campos from Michael Casper, a great person to do business with, and a fascinating individual in person.

Lee


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Kent10
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Reged: 05/08/12

Re: Best Etched Meteorites? new [Re: lee14]
      #6079737 - 09/14/13 01:58 AM

Hi Lee:
Does your method of etching give the etch more of a matte look rather than a shiny look. Or is that the difference in types of irons. I really like the look of your Campo del Cielos which don't reflect so much light. Both the Gibeon and Taza etchings I have are quite reflective as if there is a protective coat of something on there. I don't like these as much.


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lee14
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Reged: 12/19/09

Re: Best Etched Meteorites? new [Re: Kent10]
      #6080695 - 09/14/13 04:15 PM

As to any difference between nitol and ferric chloride, I can't say, I've never tried the latter. There may be minor differences between types, but I suspect how the surface is finished prior to etching is more a factor for determining reflectivity. Most of mine are finely ground to 600 grit, so the surface has a matte appearance even before etching. I used to polish everything to a mirror finish, but found it generally unnecessary. The contrast seemed better without polishing, so I left out that step since it's a pretty lengthy process anyway.

Not to say you can't get good results etching a mirrored surface. Since the acid dissolves only the kamacite and leaves the taenite unaffected, that portion ought to remain quite reflective. Some species require a fully polished surface to show a good etch, such as Canyon Diablo and Mundrabilla. Etching these after only a 600 grit finish leaves a muted pattern with poor contrast in my experience.

Some folks do coat their pieces with lacquer or polyurethane. Those should appear uniformly shiney regardless of the viewing angle. Close inspection should reveal if you've got a coated piece. If there is a sprayed on coating, you will be able to slightly dent it with a gently applied fingernail without causing any damage.

Lee


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Re: Best Etched Meteorites? new [Re: lee14]
      #6080700 - 09/14/13 04:18 PM

Thanks Lee. Your etching is really beautiful and I can't stop looking at that piece.

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Re: Best Etched Meteorites? new [Re: Kent10]
      #6081901 - 09/15/13 11:37 AM

I contacted the seller of my Taza and he said there is a clear coating on it. He says he also coats all his irons with Def clear coat. I sure would like to see my Taza without the coating. I guess it must protect it but it is so reflective I don't think it looks as good as it might.

I wonder if Def is a brand or type of clear coat.


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Re: Best Etched Meteorites? new [Re: Kent10]
      #6082409 - 09/15/13 04:51 PM

I also contacted the seller of my Gibeon and he also coats his irons. "We use a protective coating to protect our meteorites from corrosion. It is a meteorite top coat developed and sold by a company called paleo bond." It is not as reflective as my Taza though. The Taza looks "plasticy."

I just received a 2nd e-mail from the Gibeon seller. "Yes that one had a protective coating put on it called vpci 286 meteorite top coat."


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Re: Best Etched Meteorites? new [Re: Kent10]
      #6082464 - 09/15/13 05:19 PM Attachment (10 downloads)

I can't believe I just got myself another Taza. I am just disappointed with the plastic one that I have and it is hard to look at. I found this one and immediately liked it. I hope it is not coated the same. Pictures look great I think and it has an inclusion!

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Re: Best Etched Meteorites? new [Re: Kent10]
      #6083028 - 09/15/13 11:22 PM

I like the Tazas, I think I'll have to keep an eye out for a whole one.

I'm a bit familiar with Paleo Bond through their literature, but have no direct experience with the products. I believe they're highly thought of though.

I came to use gun oil as a protectant after reading an article by Allen Langheinrich (Lang's Fossils and Meteorites) on the care and preparation of irons. It appears in the August 1997 issue of Meteorite!, which I'm pretty sure is out of print.

The use of a clear coating is nice because it enables frequent handling of a specimen. I'm not sure how they hold up over time, I'd certainly be glad to hear from anyone who's had a similarly prepared slice for a number of years. I did at one time coat my pieces, but found even the tiniest bit of trapped moisture became problematic over time, compromising the coating and accelerating corrosion at that point. I like gun oil because it penetrates into any microscopic fissures, and is easily reapplied if necessary. I have quite a few pieces treated with G-96 oil, slices and whole specimens that have remained corrosion free for years, and that is in a fairly humid environment.

Lee

Edited by lee14 (09/15/13 11:24 PM)


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Re: Best Etched Meteorites? new [Re: lee14]
      #6083033 - 09/15/13 11:27 PM

I believe def clear coat is simply automotive lacquer without pigment.

Lee


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Re: Best Etched Meteorites? new [Re: lee14]
      #6083034 - 09/15/13 11:28 PM

Yes an advantage of these coatings is that it will protect nicely but if it compromises the look... In my 1st Taza I can actually see scratch marks made in the coating and it is so reflective. I don't mind the Gibeon one. It still looks quite nice but I would sure like to see it without the coating. I also like the gun oil method Perhaps when my irons start rusting or looking not so good I will have wished I had them all coated

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Re: Best Etched Meteorites? new [Re: Kent10]
      #6083488 - 09/16/13 09:22 AM

That Taza certainly has a lot going on. The inclusion is either troilite or graphite, can't be sure from a pic. The underlying Widmanstatten pattern is quite muted, but attractive. Those needle-like forms are really spectacular, and probably schreibersite, Mike would probably have a better estimation. Then there are a couple of more amorphous metallic formations at 5 o'clock from the troilite. These look just like those one often sees in Canyon Diablos. I'd say this material underwent some serious shocking.

Lee


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Re: Best Etched Meteorites? new [Re: lee14]
      #6083496 - 09/16/13 09:25 AM Attachment (7 downloads)

I like it and I hope it looks as good in person. Here is the reverse side and a close up of the inclusion.

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Re: Best Etched Meteorites? new [Re: Kent10]
      #6083497 - 09/16/13 09:26 AM Attachment (14 downloads)

Close up

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Re: Best Etched Meteorites? new [Re: Kent10]
      #6083499 - 09/16/13 09:27 AM Attachment (7 downloads)

Other side close up

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Re: Best Etched Meteorites? new [Re: Kent10]
      #6083915 - 09/16/13 01:00 PM

I'm going to say troilite rather than graphite. It has the brownish tinge characteristic of troilite (iron sulfide) rather than the grayer look of graphite. What I especially like about this one is the metal crystals arranged around the perimeter. Really nice!

Lee


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Re: Best Etched Meteorites? new [Re: lee14]
      #6084347 - 09/16/13 05:13 PM

That is an awesome Taza. The inclusion is surely graphite, but it appears to have a ring of schriebersite around it. I'm not familiar with the chemical makeup of Taza in particular, but when one sees graphite inclusions like this in an iron meteorite, there is often a ring of schriebersite around them.

Let me preface my next statement - I am not skilled with iron meteorites and I am not particularly knowledgeable about them because I don't collect them and rarely sell them. It's not a knock on irons, it's a restraint I put on myself because the high expense and learning curve of prepping and curating irons.

Also, I live in Florida, which presents a constant battle with humidity to keep my specimens from degrading while in my possession. Plus, as Lee will attest to, irons are rough on the saw, blades, and equipment. But, I have picked up some knowledge of curating iron meteorites from Pat Mulvany. Some of his knowledge rubbed off on me via osmosis over the years. I do know that coatings are generally harmful to most meteorites - in terms of contamination and loss of scientific study value. However, many irons desperately need to be saved from oxidation, so using chemical or oil treatments and coatings is a necessary evil with irons. The only big exception to this is uncut irons that have a stable, protective shale rind around the unoxidized core. Those can last almost indefinitely in a stable state if they are properly stored and handled.

Best regards,

MikeG


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Re: Best Etched Meteorites? new [Re: Glassthrower]
      #6084475 - 09/16/13 06:26 PM

Is it the ring of schriebersite that leads you to the conclusion that the inclusion is graphite? I've never worked with a Taza, but the only place I've seen graphite inclusions are Canyon Diablos. The only non-intrusive test I know to differentiate between the two is that troilite tends to stain the surface if one is slow to halt the etching process. If you've got a visual method of telling whether an inclusion is graphite or troilite, please fill me in!

Lee


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Re: Best Etched Meteorites? new [Re: lee14]
      #6088641 - 09/18/13 06:51 PM

Quote:


Is it the ring of schriebersite that leads you to the conclusion that the inclusion is graphite? I've never worked with a Taza, but the only place I've seen graphite inclusions are Canyon Diablos. The only non-intrusive test I know to differentiate between the two is that troilite tends to stain the surface if one is slow to halt the etching process. If you've got a visual method of telling whether an inclusion is graphite or troilite, please fill me in!





No, the ring of schriebersite is just coincidental - you see similar rings around various inclusions, clasts, or even around armored chondrules in some stony types.

I am guessing this is schriebersite, but I am not sure. The schriebersite would be the innermost ring around the inclusion, and the lamellae radiating outward from it are probably the usual taenite or kamacite.

As for the inclusion, graphite is my guess, but I am not 100% certain - I probably sounded more certain at first, but after studying the photos more closely in Photoshop, I am not sure now - it could be graphite or troilite. I am still leaning towards graphite because of the color and apparent texture in the photo. The majority of easily-identifiable troilite I have seen has a brassy hue to it. But, troilite doesn't have to be brassy - it can appear greyish or it can have the same hue/color as the other metal in a given meteorite.

In general, most graphite inclusions are a bit darker in appearance than this one. And, as far as I know, graphite is not common in Taza (NWA 859). So I could be very wrong on this. A hardness test on the inclusion might narrow down the possibilities - graphite is softer than troilite, unless it is so highly shocked that the graphite has become hardened.

I would try scratching the surface of the inclusion and find out what the hardness is. Graphite is 1.5 on the MOHS scale, so you should be able to scratch it with your fingernail. If you can't scratch it easily, then it's likely not graphite - unless it is highly shocked.

Best regards,

MikeG


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Re: Best Etched Meteorites? new [Re: Glassthrower]
      #6089564 - 09/19/13 09:07 AM

It occurred to me a streak test might be informative, but they seem to be fairly close in appearance, graphite leaving a black, and troilite grayish-black. Streak combined with hardness tests should give a pretty good level of certainty, but I think qualitative analysis would be the only completely accurate determination. Thanks Mike!

Lee


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Re: Best Etched Meteorites? new [Re: lee14]
      #6089977 - 09/19/13 01:26 PM Attachment (9 downloads)

This is definitely a graphite inclusion, in a Canyon Diablo. The overall pic is poor, but I tried to make the appearance of the inclusion as faithful as possible to the actual color seen in daylight. It's gray, not a hint of brown. For what it's worth...

Lee


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Re: Best Etched Meteorites? new [Re: lee14]
      #6102683 - 09/26/13 04:59 PM

I received the Taza today. It is just unbelievably beautiful. And there is no contest when compared to my 1st one with the coating on it. The new one sparkles. So glad I got it!

I wish it was easier to tell from pictures what these irons will look like when you get them. Some are bright and when changing angles in the light different spots light up. But then I have others that are dull looking and in light it is difficult to get the same effect. Best to buy in person I suppose if at all possible.


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