[meteorite-list] blue chondrule in a CM2

From: Jeff Kuyken <info_at_meteoritecentral.com>
Date: Sun, 7 Feb 2010 11:11:48 +1100
Message-ID: <4922A94A6233467DBADD2254E3AFC93D_at_JeffPC>

Hi Zelimir & all,

It was quite a few years ago now but at the time I think there were a few
scientists who took a look at my pics and they all had a similar and
independent opinion of "Hibonite". I would tend to go with the Hibonite
theory too. These have all been found in meteorites with CAI's but I am yet
to see anything remotely similar in an ordinary chondrite. Mine is slightly
different to yours in the respect that it has been sliced right through the
middle. I have slightly polished that endcut to remove previous heavier
polishing marks and there was no change in appearance of my inclusion. It
seems to be a solid blue CAI or chondrule.

Cheers,

Jeff


----- Original Message -----
From: <Zelimir.Gabelica at uha.fr>
To: "Ted Bunch" <tbear1 at cableone.net>
Cc: <meteorite-list at meteoritecentral.com>
Sent: Sunday, February 07, 2010 9:20 AM
Subject: Re: [meteorite-list] blue chondrule in a CM2


Hello Jeff, Matthias, Ted, all,

Your wise suggestions about the blue inclusion are highly appreciated.

I also first thought of hibonite that was mentioned in a similar
discussion we had on the list a couple of years ago. At the time, Jeff
Kuyken showed us a chondrule-like inclusion in Isheyevo and hibonite
was one of the hypotheses retained . I don't really remember the
detailed discussion that resulted but this info is now probably hidden
somewhere in the archives .
By luck, this debate (with hibonite hypothesis) as well as the
inclusion pics are still available on Jeff's site (Jeff K, I hope you
don't mind if I provide the link):

http://www.meteorites.com.au/features/isheyevo.html

The blue color in Isheyevo (as it is in Allende shown by Ted), is more
intense than the light blue shade of our TNZ "chondrule" so I did not
retain at first that hypotheis. (also because all the terrestrial
hibonites I have seen are dark brown but more often just black; the
best crystals so far come from Madagascar and I have in my mineral
collection a 6x4x3 cm single cristal, just full black- from the famous
Betroka deposit).

I now realize the hibonite hypothesis is very likely.
But enstatite is another possibility indeed. I have a terrestrial
enstatite sample that is blue-green. The synthetic enstatites we once
had synthesized in the lab are logically white.

Two last questions (sorry for insisting):

1) Should we consider this just as a curiosity or does someone believe
this could have some pertinent significance in the case of a CM2
chondrite ?

2) How can we make sure the "round light blue circle" shown here is a
chondrule or a CAI ? Jeff firmly states that the TNZ hibonite is
embedded in a CAI and Ted shows the same in Allende. Would that imply
the TNZ "circle" is also a CAI rather than a chondrule, despite of its
quasi perferctly round shape ?

My best wishes,

Zelimir



Ted Bunch <tbear1 at cableone.net> a ??crit? :

> Dear Zelimir- Jeff beat me on the response.
>
> Attached is a true hibonite in an Allende CAI. Your blue object could be a
> lighter blue hibonite or an enstatite chondrule that, on occasion, has a
> blue hue depending on the light source, angle of illumination, light
> scattering, etc.
>
> Ted
>
>
> On 2/6/10 10:06 AM, "Zelimir.Gabelica at uha.fr" <Zelimir.Gabelica at uha.fr>
> wrote:
>
>>
>> Hi List,
>>
>> Here are 3 pics of a genuine blue chondrule spotted upon breaking a
>> fagment of the CM2 meteorite Tanezrouft 082 (purchased last June in
>> Ensisheim, from A. Gouesslain/J.-L. Parodi, the meteorite finders).
>>
>> See here:
>>
>> http://www.agab.be/question/question.html
>>
>> Question: what could be the origin of such a strange turquois-like
>> blue color ?
>>
>> Could it be due to some traces of Cu2+ salts neutralizing some
>> refractory silicates ? (despite tha fact that the presence of Cu was
>> apparently not reported in the meteorite analysis, see the Met. Bull.
>> writeup added in the URL).
>>
>> Or could that just be (sometimes) the natural color of some
>> (ortho)pyroxenes ?
>>
>> Or olivine ?
>> However, I don't remember having ever seen any olivine showing such a
>> "true" blue color. Shouldn't olivine (always?) rather be
>> "olive-green", whatever its origin (terrestrial or asteroidal) ?
>>
>> Thanks for sharing your thoughts or expertise.
>>
>> My best,
>>
>> Zelimir
>>
>>
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>



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Received on Sat 06 Feb 2010 07:11:48 PM PST