[meteorite-list] Cornucopia of chondrules

From: Martin Goff <msgmeteorites_at_meteoritecentral.com>
Date: Wed, 12 Mar 2014 14:04:46 +0000
Message-ID: <CAKEL=tBYMcC8ThzAqGUu5zCpg2kmip11-n1T5QEyLKmDkpBEpA_at_mail.gmail.com>

Hi Bernd, all,

Problem sorted! I have now solved the issue after i realised that i
had an attachment on the microscope that was causing the colour shift.
I had a zoom attachment that enabled me to change the magnification
seamlessly from 0.8x to 2x which was very useful for framing when
taking photos. However now that is removed the colours are as they
should be. The results when using this were very much like using an
additional wave plate.This was obviously adding in some unwanted
polarising effects I have now uploaded some before and after photos
with the zoom attachment and without so you can see the difference.The
images are numbered 1 to 10 and the upper image is the with the zoom
attachment and the lower image without. Link is as before:

(https://www.flickr.com/photos/94515040 at N03/)

Thank you again Bernd for pointing out the colour shift in my images :-)

Cheers

Martin

On 11 March 2014 21:06, Bernd V. Pauli <bernd.pauli at paulinet.de> wrote:
> Martin writes:
>
> "I have now made an attempt to identify the different chondrules,
> hoping some folk with much more knowledge than me can chime in
> and correct my mistakes!"
>
> Hello Martin, Rob, and List,
>
> Martin, congrats on your colorful thin section photos! Well, colour is
> the problem I see myself faced with when looking at your thin section
> pics. They look almost too colourful. Are you sure the section has the
> proper thickness of 30?m (= 0.03 mm)?
>
> Here are my numbers for your thin section pics so you and the other
> list members know which pic I'm referring to:
>
> 1--2--3
> 4--5--6
> 7--8--9
> 10--11--12
> 13
>
> Now, #1 does look like an RP chondrule at first sight but if it is a radial
> pyroxene chondrule, the interference colours are too high. They should be first
> order, i.e., gray or grayish-white. Either the TS doesn't have the proper
> thickness or we are looking at something else: the high interference colors
> would speak in favour of a deformed (?) BO chondrule with slender bars.
>
> Chondrule #10: same problem! Provided the IF colours are correct, this
> is another BO chondrule. If it is an RP chondrule, the interference colours
> are wrong.
>
>
> My NWA 5730 has lots of metal-rimmed chondrules, FeNi is troilite-rimmed,
> porphyritic chondrules are abundant, numerous porphyritic chondrules harbor
> light-green translucent hypersthene crystals + a gray clayey-looking broken
> chondrule (d = 5.1 mm). I wonder if it is something carbonaceous or if it
> experienced some kind of silicate darkening.
>
> Best wishes from the owner of a 21.4 gr endcut that I got from Rob in 2011!
>
> Bernd
>
>
> ______________________________________________
>
> Visit the Archives at http://www.meteorite-list-archives.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list

-- 
Martin Goff
www.msg-meteorites.co.uk
IMCA #3387

Received on Wed 12 Mar 2014 10:04:46 AM PDT