[meteorite-list] West - Blue-Silvery Markings

[ensoramanda at ntlworld.com]

Hi Tom, All...

The metallic sheens produced in ceramics..eg Raku, are not produced by metal vapors but by subjecting the metal oxides in the clay or glazes to an environment without oxygen whilst still red hot (not sure of the actual temp without research) often this is by introducing gases to the kiln or removing the pot from a red hot kiln and plunging it into dead leaves or newspapers. Thus you get a reduction of the oxides as the combustables suck away the oxygen leaving the pure metals...often producing wonderful sheens in all colours....various copper and iron oxides are usually used.

So for the same mechanism to work on the fusion crust of a meteorite it would have to be when it was still incandescent... I think...in a poor oxygen environment.

So how much oxygen is there up where the West fireball was still burning???

If very little then that could be the cause...but I would have expected it to happen much more often, unless Sau 001 and West have a particular oxide in their matrix which is more prone to reduction when fragmented high up as they probably were.


Graham Ensor, UK.


---- STARSANDSCOPES at aol.com wrote: 
> Hi Robert and list,  I just looked at the  post of the image on Michael's 
> site (Thanks!!!).   
> 
> http://www.rocksfromspace.org/West-markings.html
> 
> 
> SaU 001 has  a copper metallic sheen on some of the examples.  I wonder if it 
> is the  same process at work?
> 
> I am convinced it is the result of metals internal  to the meteorite 
> vaporized and depositing in the crust.  Very similar to  pottery glazes.  Different 
> metals=different colors.  This metallic  glaze has stood up to hundreds of years 
> in the Oman desert.  I think it is  in the glass of the crust (so to speak).
> 
> I have taken some heat on this  but I have tried to wear the glaze off by 
> carrying small samples in my pocket  for extended periods.  It is in the glass 
> that forms the crust and is not  part of the weathering process as has been 
> suggested in SaU 001.  In fact  this metalic finish has been dismissed as just a 
> weathering phenomenon.   
> 
> I am very excited to see a similar looking deposit on a fresh  fall.
> 
> Email me for some cool SaU 001 crust shoots but be advised, I am  not as good 
> with macro as micro!
> 
> Tom Phillips
> 
> In a message  dated 3/10/2009 6:03:32 P.M. Mountain Daylight Time, 
> meteoritefinder at yahoo.com  writes:
> 
> List,
> 
> I have been meaning to ask about the  "blue-silvery" markings on some of the 
> West specimens we found. I see that  McCartney Taylor mentions it on his new 
> web site. I showed the 60g meteorite  that it is best represented on from our 
> finds to several "in-the-know-guys",  such as Mike Farmer and Robert Haag, who 
> both have a seen a LOT more meteorites  than I have. Neither of them had ever 
> seen anything like it before. That seems  to be a fairly significant 
> statement.  Robert tossed around the idea that  it MIGHT be related to the copper 
> content in this meteorite, and MIGHT be some  kind of "copper-related-melt-splash" 
> ????? ( Not trying to start any wild,  fantastic claims here at all. Like I 
> said, this is just some musings out loud.  He also said it might be some type of 
> troilite melt-splash, or something else  completely. But the point is, 
> wouldn't most of us agree that if NO one (that  I've asked) has seen something like 
> this before, it must be fairly uncommon  at
> the least??? 
> 
> If anyone has ever seen anything like this  before or knows what it is, I 
> would love to hear from you.
> 
> I don't  have a website, or a photo hosting site, but I would be happy to 
> send a photo  that displays the markings directly to anyone who requests it.
> 
> Thanks,
> Robert  Woolard
> 
> 
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