Meteorite Mailing List Highlights

re: Curation of meteorites containing organics

From: Jim Wooddell
To: Meteorite List
Subj: re: Curation of meteorites containing organics
Date: Apr 30 08:20:00 '12

Hi Carl and all! This is an important topic as I think most experience hunters will comply with sound advice. I brought this up because what I am seeing in the field first hand does not appear to be working well at all! Now, it might if the specimen is immediately placed in an additional protective container and not moved or messed with again, but with 90% or more of the finds, that is just not happening. Issues to consider are not only contamination, but the effects any metal has on other metals and metal oxides and sulfides. Just off the top of my head, Galvanic corrosion which occurs immediately upon contact. Then there is the Peltier Effect (thermocouple reaction) and the Thomson effect. Excluding any of the corrosion issues, it is also very much related to handling issues. It is very evident the fragments of this Sutters Mill meteorites can easily crumble. The specimens with complete 100% fusion crust are better protected, but when I was there, only a few had been found at the time. Most were fragments. That known, putting them in aluminum foil DOES NOT help that issue. Instead, I think it makes it worse. I've always followed this which is in our CFR's: (1) Handling requirements. Handling procedures shall ensure that the specimens are properly labeled and handled to minimize the potential for contamination from the point of collection to the point of curation. At a minimum, handling procedures shall include: (I) Handling the samples with clean Teflon or polyethylene coated implements or stainless steel implements (or equivalent); (ii) Double bagging of samples in Teflon or polyethylene (or equivalent) bags; While Teflon bags (PTFE) are likely inert, polyethylene bags should be a good short term field storage. So, as my final comments.... The aluminum foil, as handled in the field, will provide unknown contaminants and the contamination will not be consistent from sample to sample. It can damage the fragile samples easily and will create a Peltier Effect as well as galvanic corrosion immediately upon contact with any other metal. Hopefully it will be the "weaker" metal and take the brunt of the corrosion! But with CAI's and such??? The plastic bags, will have a more consistent level of contamination and be relatively consistent from bag to bag in the same lot. They will not have any of the effects of electrical corrosion mentioned above because of their insulation properties of DC currents. And they are friendly to the sample contained within as opposed to crinkled up aluminum. In this case, it had rained and the dew on everything was major. Many samples found in parking lots! So, all we could possibly do is reduce further contamination of the human kind. The best protection I saw in the field is where we double bagged a sample, never touching it and then placed it in a large soft cloth. Just my 5 cents! Cheers! Jim

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Curation of meteorites containing organics

From: Carl Agee
To: Meteorite List
Subj: Curation of meteorites containing organics
Date: Apr 30 06:34:00 '12

I just saw Jim Wooddell's post about aluminum foil and the new CM fall. It turns out that aluminum foil does react somewhat with carbonaceous chondrite. Apparently the recommended storage material is Teflon. This is what is used in NASA's Lunar Lab (Teflon bags and gloves). Cold and dry (nitrogen) storage are recommended too although if this meteorite has been sitting in the rain, then it may be moot. Take a look at Chris Herd's presentation of lesson's learned from Tagish Lake and Buzzard Coulee: www.lpi.usra.edu/meetings/sssr2011/presentations/herd.pdf

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Sutter's Mill meteorite hunt

From: Michael Farmer
To: Meteorite List
Subj: Sutter's Mill meteorite hunt
Date: Apr 25 22:14:00 '12

Day two of the meteorite hunt ended with no new finds other than a few fragments of the parking lot specimens here in California. Many people are here, some new faces, most well known, all hunting for the fall of a lifetime, a CM2, only California's third fall. I walked many miles today, with nothing to show but sore feet, but i did buy out ~1gram of fragments recovered from the parking lot piece found by Dr. Jeniskens. more pieces were scattered in the lot. Sadly this rarest of rare meteorites fell in one of the toughest terrains I have ever had the displeasure of searching for meteorites in. As of right now less than 15 grams has been found despite large scale search. Of course that could change at any moment with the right find. So far it has been fun, i almost stepped on small rattlesnake today, so be careful, he did not rattle. Police were involved in a couple of hunters day for innocent reasons, seems landowners called cops even when hunters had permission, people are kind of private up here, and park rangers were getting interested in people hunting for rocks. It could get interesting really fast with tomorrow's barrage of news that is coming down the pike. Still, this is one of the rarest falls on my lifetime, and worth working oneself nearly to death to try and find. i hope as much as possible is recovered for the science that can be done. Congrats again to Robert Ward for finding the first smallest needle in the worlds largest haystack, something that 50 people today did not duplicate.

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Met Bulletin Update - Ackerly L5 Texas Find

From: Galactic Stone and Ironworks
To: Meteorite List
Subj: Met Bulletin Update - Ackerly L5 Texas Find
Date: Apr 25 09:32:00 '12

Greetings Bulletin Watchers, There is one new approval in the Bulletin today. It is Ackerly, an L5 find from Texas. Link - http://www.lpi.usra.edu/meteor/metbull.php?code=55379 Best regards, MikeG

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Pairing S-Type Asteroids to OCs (from Arkansas)

From: Mexico Doug
To: Meteorite List
Subj: Pairing S-Type Asteroids to OCs (from Arkansas)
Date: Jul 09 11:45:00 '08

http://www.sciencedaily.com/releases/2008/07/080710103903.htm The press release was confusing to me at first, highlighting the Fayetteville H4 (fall, Arkansas) meteorite. Perhaps they did because of being fresh and closer to the surface (?) in the parent body model. Not sure why the 1270 Datura family, etc., would be expected to be from the relatively rarer surface of the original parent body vs more common heat altered interior). In any caseit seems they are NOT claiming that (1270) Datura is the parent body to any of our meteorites (how could it be - don't virtually all ordinary chondrites have CRE's of floating around as meteoroids well over 1 million years?) However, it seems they are pointint out that because it is an S-type asteroid that has apparently suffered a collision only 450,000 years ago(which was shown by other researcher a studying the probabilities of members' orbits couple of years ago), it gives an opportunity to study fresher material of this most common high silicate asteroid type by telescopic spectroscopy, and they had an opportunity to take the spectra. I guess they only look at the 0.5 and 1 um peak because it is more sensitive to space weathering (?), but this isn't too clear either. (the authors didn't extend it to the typical 2.5 microns where some good stuff is visible - at least not in figure in the press release). In any case, their proposed contribution seems that they measured spectra of theyoung Datura family and compared it to ordinary chondrite spectra and got a better match than ever before helping to solve the conjecture that the common asteroid class (second only to supposed carbonaceous chondrites typed asteroids) should be paired to common meteorites. Hopefully they make a case for a trend in asteroid reflectance spectra vs. age, vs. a one hit wonder, but there still seem to be more complexities to be ironed out regarding what meteorite is appropriate to compare to what asteroid in the clan, IMO. Maybe Fayetteville was just selected because it is what they had access to... Article sounds like it will be a good one. Comments? Best wishes, Doug PS Interestingly, Wikipedia (at this moment - no doubt it will be fixed by someone reading this) says the Datura cluster formed 450 MILLION years ago and a probable source of zodiacal dust.... Maybe Wikipedia can't be trusted yet again, once the dust has settled :)

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