[meteorite-list] Cornucopia of chondrules

[rickmont at earthlink.net]

Martin, Bernd et al,
Wonderful photos, and I immediately wondered the same thing.  As a painter 
of faux (not reality) chondrules, I have steered away from pyroxene so far 
simply because I want to explore grays and black-and-white before tackling 
the radial chondrule. (The big picture includes larger works with types 
3-4-5, eventually into achondritic fantasy-land....).  Bernd, you have shed 
some valuable light!  If I am concluding correctly:  thicker slices in TS 
can cross into higher order colors for pyroxene?  Ah!  This will be my 
excuse if I am confronted with a colorfully painted pyroxene element by the 
true meteoriticist!

I will strive to be true to the "accepted" dimension however.  So, 
meanwhile, Martin, can you share info on the depth of your slice-photos?

Sincerely,
Richard "Rick Bob" Montgomery


-----Original Message----- 
From: Bernd V. Pauli
Sent: Tuesday, March 11, 2014 2:06 PM
To: meteorite-list at meteoritecentral.com
Subject: [meteorite-list] Cornucopia of chondrules

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 30µm (= 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


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