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Meteorites to Avoid

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#1 Kent10

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Posted 27 August 2013 - 01:59 PM

Hi All:

This is my first post on the Space Rocks forum.

The other day my daughter was asking if I would ever buy a meteorite. I was looking on Astromart at that moment and one popped up for a very reasonable price so I bought it. This got me really interested in meteorites so I did a little reading and got excited and bought a few more :grin:

I didn't really know if I paid too much for them but I did some comparison shopping so I don't think I paid way too much if I did. But I liked the looks of these even though I either knew nothing or very little about the history. I was buying to get started.

Anyway, I did some more reading and found out how you have to take care of the iron ones and that they might rust. OK, I thought, that would be a shame for them to rust so I thought I could take care of them and at least I live in a dry climate.

Then my latest acquisition was a small Admire Pallasite. I thought my daughter will really like this one.

I have since read that some of these are not very stable. I have read different opinions, however. So I am wondering if anyone has more information on these. Are they unstable or does it depend on something. How long might they last?

I have enclosed some pics of ones that I have bought. I bought mainly on aesthetics rather than knowing much about them. But now I want to learn more! Lots of fun but I hope I don't spend too much :( What do you think of my starter collection? Are there any others to avoid that might be rusters or not stable? Thanks very much, Kent

Here is the first one that got me started.

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#2 Kent10

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Posted 27 August 2013 - 02:00 PM

Here is the Admire Pallasite

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#3 Kent10

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Posted 27 August 2013 - 02:01 PM

3

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#4 Kent10

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Posted 27 August 2013 - 02:02 PM

4

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#5 Kent10

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Posted 27 August 2013 - 02:02 PM

4 reverse

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#6 Kent10

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Posted 27 August 2013 - 02:03 PM

5

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#7 Kent10

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Posted 27 August 2013 - 02:05 PM

5 reverse

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#8 Kent10

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Posted 27 August 2013 - 02:05 PM

6

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#9 Kent10

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Posted 27 August 2013 - 02:07 PM

7

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#10 Kent10

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Posted 27 August 2013 - 02:08 PM

7 reverse

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#11 Kent10

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Posted 27 August 2013 - 02:08 PM

8

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#12 Kent10

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Posted 27 August 2013 - 02:09 PM

9

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#13 Kent10

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Posted 27 August 2013 - 02:10 PM

10

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#14 Kent10

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Posted 27 August 2013 - 02:10 PM

10 reverse

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#15 lintonius

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Posted 27 August 2013 - 02:58 PM

Looks like you're off to a good start, Kent! Several nice specimens there... some that I recognize. I bought my first meteorites on Astromart, too... in 2005, I think. Prior to that, I had no idea one purchase their own space rock, to have and to hold. So I bought 3, thinking that would be he end of it. Ha! I have hundreds now, and need to scale back quite a bit!
Get a copy of Richard Norton's Rocks from Space to start learning more about them. And have fun! But be aware... they're addicting!
Linton

#16 Kent10

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Posted 27 August 2013 - 03:03 PM

Thanks Linton. And thanks for the book recommendation. I was thinking a book would be a good idea. I can't believe how sudden all of this was though. Just because my daughter was talking about it. I just received the small one #3. I knew it would be small at .5 grams but wow it really is small. I need a magnifying glass to really appreciate it.

#17 lintonius

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Posted 27 August 2013 - 03:53 PM

I knew it would be small at .5 grams but wow it really is small. I need a magnifying glass to really appreciate it.


Yeah, a magnifying glass is a must, even for larger specimens.
But a stereo-microscope will be on your list before long! <g>
Linton

#18 Kent10

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Posted 27 August 2013 - 04:01 PM

Ah a microscope. That reminds me. I do have a very good one that hasn't been used for years. It belonged to my dad who is now retired. I may have to get it out sometime. Under the light that .5 gram "stone" really has some nice features. It glitters. Thanks.

#19 Glassthrower

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Posted 28 August 2013 - 02:31 PM

Hi Kent,

Welcome to Space Rocks. And welcome to a new lifelong obsession. Meteorites are like potato chips..... Just ask my poor wife. ;)

You don't need to "avoid" certain meteorites because of rusting issues - instead, just avoid paying too much for them.

The majority of stability issues (rust, lawrencite, etc) are not caused by some inherent problem with the meteorite itself. Most instability is avoidable and occurs during poor preparation work where corners are cut to save time and money. Properly prepared, there really is no such thing as an "unstable" meteorite.

Nantan, Campo, and Admire are 3 good examples of meteorites with a bum rap as being instable. And yes, there are tons of examples of rusting Nantans on the market that look horrible. But, when properly prepared, it can be just as stable as any other iron meteorite.

Irons are much more problematic than stones and stony-irons tend to be a mixed bag. And oddly, some of the biggest and most well-known dealers on the planet do not properly prepare their specimens. I can't and won't name names here, but don't assume that a specimen you get from any famous dealer is stable - quite the contrary sometimes.

Over time, you'll get a good feel for who the dealers are who do the proper prep work without cutting corners. Word of mouth is a good place to start, as is a search engine.

If you have any questions, feel free to shoot me a private message - I can be much more candid in private, because I am a vendor and can't say certain things in the open forums. :)

Best regards and clear skies,

MikeG

#20 Kent10

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Posted 28 August 2013 - 03:20 PM

Thanks Mike. Very informative. I had this picture in my mind of my Admire piece falling apart. I guess that could be quite some time if it ever happens. I hope mine was well-prepared but I may never know unless it starts falling apart.

Thanks again, Kent

#21 Glassthrower

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Posted 28 August 2013 - 07:58 PM

The main source of contamination during prep work is chlorine from tap water. Many cutters use tap water to save time and money. One should only use distilled water to cut meteorites. Why so many people ignore that is beyond me, because distilled water is cheap.

The second main source of instability is insufficient drying after the prep work. Once a meteorite is cut and/or polished, it should be baked in a hot oven for several hours to purge remnant moisture.

Failure to observe those two simple rules results in many unstable pieces and disappointed collectors.

There is little way to tell if a specimen is unstable unless it is already showing signs of rusting. Over time, you will see which specimens are stable because the unstable ones will start to bloom little rust spots or weep a reddish-brown liquid.

Stones are much less problematic. Ideally, your irons and stony-irons should be handled only rarely and wiped clean with an oily cloth after handling. Store or display the specimen in a climate-controlled area in an airtight container that has dessicant inside it to absorb ambient moisture. This will retard any stability issues, but will not fix them.

Best regards,

MikeG

#22 Kent10

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Posted 28 August 2013 - 08:37 PM

Thanks for the advice Mike. I did buy the Rocks from Space book so I will learn more soon. Is the "oily" cloth something special. I couldn't find many references to this specifically and none for sale. Thanks.

#23 Michael Rapp

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Posted 29 August 2013 - 03:12 PM

Mike, would it be a good idea to bake any meteorite one acquires in an oven as a precaution, or it is useless as any damage from remaining moisture would have already been done?

#24 Glassthrower

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Posted 29 August 2013 - 04:43 PM

Hi Michael,

Good question. In my experience, it's not really needed if the specimen appears stable and doesn't exhibit any outward signs of rust or lawrencite disease.

Stones are a special case. For the most part, they are very stable for collectors. They will rot if left exposed for prolonged periods in the field, exposed to the elements. But, in the average collector's air-conditioned environs, they hold up very well or indefinitely.

However, a few stones are known to be problematic. I didn't mention them earlier because the original post was about irons, but I should list them now. Also, the main culprit that afflicts stony meteorites is "lawrencite disease".

Ghubara - this one can be a prolific ruster and is prone to lawrencite. Why? Honestly, nobody has studied it and nobody can say for sure. I think it's a combination of long-term exposure to irregular rains on the semi-arid Omani plateau, and improper handling/storage/preparation in subsequent possession of hunters, middle men, and dealers.

Ghubara (and some others) may develop little reddish or brownish spots that look like common rust. In fact, it is a reddish fluid that is the result of a chemical chain reaction in the meteorite itself. It will soon weep more and more. You can wipe it down, clean it with a stiff brush, and bake it in an oven. And it will help the appearance, but the lawrencite disease is still lurking hidden in the matrix of the meteorite. It will continue to "bloom" these little beads of rusty liquid and the specimen will actually start to break down and become more friable. Slices may break or pieces will break off. Brecciated meteorites with this affliction can actually fall apart over time.

The cause of this is the introduction of molecular chlorine into the matrix of the meteorite. This is due to terrestrial contamination in the vast majority of cases. For example, using tap water as a coolant during cutting will introduce chlorine into the meteorite. No matter how well you dry the specimen afterwards, the chlorine will remain - it will react and bond with some of the material in the meteorite. These reactions produce a variety of effects, but the most noticeable is the weeping of reddish fluid.

This can be completely avoided by using distilled water during cutting and polishing. Baking them in the oven afterwards is a good "double-whammy" to prevent stability issues in prepared specimens.

Any dealers reading this who do not use distilled water and baking, please take notice now. The most important step in any prep is the saw coolant and distilled water is essential to avoid contamination of any kind. (lawrencite or otherwise)

Back to the point of the original post, no, you don't need to bake your meteorites. But, if they exhibit signs of problems, then you might want to consider it. If you stick to oven temps of about ~225F to ~240F, and don't bake for more than ~16-20 hours, then you cannot hurt a specimen by doing this.

Be careful baking etched irons - high temps and prolonged baking can damage the appearance of the Widmanstatten pattern and may require the meteorite to be re-etched.

Best regards,

MikeG

PS - that's the short answer. :lol:

#25 Glassthrower

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Posted 29 August 2013 - 04:45 PM

Almost forgot, more stony meteorites known to have issues - Saratov and SAU 001. Some NWA desert meteorites also.






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