[meteorite-list] Cleaning OC's

From: joseph_town_at_att.net <joseph_town_at_meteoritecentral.com>
Date: Mon Jul 3 22:23:02 2006
Message-ID: <070320060315.16133.44A88BE30008928E00003F0521602813020299019BA1089F0A9C0106_at_att.net>

Hi all,

I've heard this issue addressed before but the answers are kind of vague. I just bought a few PF's that were picked up the morning after the fall. They were stored in baggies. They are very nice with thick rich crust but they are starting to freckle. Doug offered this not long ago;


"Walter N. wrote: >>I guess the best way to find out is just go ahead and do it. ONE THOUGHT - Why distilled water? I always use tap.<< Hola there again, The "Just do it" jingle has a lot going for it in this field. After you just do it...please just tell it! I have a nice 8" saw (which is why the blade prices I quoted were a bit high - sorry). The distilled water is basically for the same reason you want to put distilled water in your car's radiator, never tap. People do it of course but then the steely insides of their circulatory system begin to corrode and make this ugly brown gunk (meteorite cyanide) and car gets a case of what meteorite people know better informally as Lawrencite Disease, which you can read about attacking iron meteorites in O. Richard Norton's classic book (Illustrated by his talented wife, Dorothy), "Rocks from Space". While the stony meteorites don't have symptoms immediately as bad as the irons, like concrete, they do absorbe a lot of water. You can
  exper
iment to find out how much with a cut open meteorite, a precision scale and an oven. It'll take about three hours at 160 170 degrees F to start talking turkey w/r to drying them. Tap water any some other forms of chlorinated water releases halide ions and as an atom is possibly involved in the catalytic oxidation of iron. A stony which is not to far weathered (i.e., has a good quantity of its reduced iron flecks intact, among other measures) like a sponge will get impregnated with the suspected bad stuff mentioned and eventually your beautiful slice which had white steely reflections will develop amber brown measles in there place. It can be repolished as many undoubtably are sadly on eBay, but it won't last shiny forever for you can suspect why. Using tap water is a classic case of irresponsibility in meteoritics though undoubtably someone out there in my cyberzoological garden will defend it. (May they come forth so I put them on my piddly black list of suppliers). Multiple
  alcoh
ol soaks is way to go for highest drying efficiency and contaminant removal. Once should be fine iuf you use distilled H20 and maybe unnecessary in that case. But if you use anything besides pure alcohol or distilled water then you really should be doing alcohol soaks. Each saok can remove a heafty % of the corrosives. While you do it, you can try to comfort yourself with the knowledge that meteorites are special compared to 99.999995% of the rest of the Earth rocks due to their containing reduced iron that is vulnerable to rusting (and chlorine also is the trick to dumping corrosive table salt in the water since ther are alway sodium ions in these cocktails looking for partners.) A beautiful geode or agate doesn't mind tap water because it is quite stable. This is a case of one rock's cosmetic bath is another rock's poison. Hope that clears it up more than mud. Please read up on it, I am sure I missed a few good thoughts on this and interpreted a couple of things too conserv
 ativel
y, but that's how I look at the world, Saludos, Doug (best oven temp is about 160 deg F for an hour min. You may "just" be dealing with NWA's but the pride you'll probably have in your product will probably be woth the inconvenience many times over, not to mention in helping you develop good technique for more financially challenging meteorite situations. But some people use IR heat lamps (available at home depot and using less power) with alledgedly superb results...(PS another expert out there signs messages JWG. I am not sure if he can add to this on blades, but as you experiment more he is also nice oracle to have up your sleeve and kindly shares info.)"

I found it to be helpful but am hesitant to try it on thick, frothy fusion crust. I'm afraid the crust will crumble and flake. I cleaned one lesser piece, with MEK, which didn't look as fragile and there was a loss of crust from the pressure of the toothbrush. I tried several brushes before I found one that the MEK didn't dissolve, lol. There's so much info. about cleaning irons but not much about OC's. Any ideas?

Thanks,
Bill

 

 
Received on Sun 02 Jul 2006 11:15:48 PM PDT