[meteorite-list] AL HAGGOUNIA 001 ("NOT" AUBRITE)

From: Jason Utas <meteoritekid_at_meteoritecentral.com>
Date: Sat, 1 Dec 2007 03:24:20 -0800
Message-ID: <93aaac890712010324h770661d5jeba79d41aa722045_at_mail.gmail.com>

Hola Adam, All,

>I never called it a type three if you read my emails
although I am confident with the designation
scientists with decades of experience assigned it.

Interestingly put. Well, I did read your emails, as well as those
posted by your brother, and, to be frank, although you don't state
that it's a type three, you do appear to support Greg's claims without
fully coming out and saying it. You say as much with this statement:
"I am confident with the designation scientists with decades of
experience assigned it."
You're clearly stating that you believe a certain designation assigned
to the stone, out of the several so far put forth by scientists.

Which designation, might I ask, since you just clearly implied that
you do not support the theory that it is, in fact, an EL3, is the one
in which you believe?

...Since you don't believe it to be an Aubrite (due to a lack of polysynthetic
twinning, as you say), the choices remaining are, I believe, EL6/7 or EL3.

And yet, based on your next statement (that big block of text just
below this, led by a >), I would assume that you support the EL3
classification.

This is contradictory to what you just said up top.

I admit that I might just be reading too deeply into this and you
might, in fact, not agree with the EL3 classification (but are still
trying to justify it for a reason that I cannot fathom, as you did
imply that you believe something different), but you don't, anywhere,
support the EL6/7 classification.
You lost me with your above statement...would you care to expand upon it?



>Not only is the object in earlier posted image an
obvious chondrule, it is a very well-formed,
sharp-edged radial pyroxene chondrule (with a clear
annular rim) containing glass (now largely dissolved
out), and this and others like it are the basis for
the Type 3 designation, along with the fact that the
matrix is not at all recrystallized but instead
"primitive".

Right. There are a few primitive chondrules - I never denied this
fact, just as you never stated that it's a type three chondrite. I've
seen the pictures as well as everyone else who cares. In fact, I've
affirmed the existence of chondrules at every point, so I see really
no need to further this.
The degree of metamorphosis of individual chondrules is, in my
opinion, generally irrelevant. If one has to cut kilos of material to
find nice unequilibrated chondrules, well, again, I could do the same
with Gao, but that wouldn't make it an H3.


>Finally it is not the low abundance of
chondrules that is important, but their form and glass
content and the matrix texture as confirmed by several
chondrite experts.

Says who? I've never seen a "type three" chondrite lacking in
chondrules like this before, have you?
Well, I'll answer 'no' for you and move on.
To be perfectly frank, I believe that the ordinary EL3 class assigned
to the meteorite is wrong.
It is clearly not an ordinary EL3, though it may contain sparse
unequilibrated chondrules.
Technically it may be a type three of some sort, and it may be an
EL-something, but one can't say it's both an EL and a type three,
because together those two characteristics combine to create a very
different-looking type of meteorite, at least with regards to
previously known EL3's.


>As far is it being an Aubrite, there is the lack of a
distinctive type of microstructure (polysynthetic
twinning) in the enstatite grains in the Al Haggounia
material, but which to my knowledge is present in all
aubrites (because of their high temperature igneous
history).

True, and well put, but this wouldn't rule out its being a primitive
enstatite achondrite.
It would point towards the stone not being a full-blown
metamorphically altered Aubrite, but, the distinct lack of chondrules
throughout most of the stones also, in classical terms,would rule out
its being a type three. Thus, as I previously stated, it technically
fits into neither class.


>Finaly, the so-called f-clasts found in some real
Aubrites are from brecciating impactors but this is
not what we're talking about here. The chondrules
found in Al Haggounia 001 are clealy native to the
matrix and not from an impactor so this argument holds
no water.

Well, let's assume that it was a primitive enstatite achondrite parent
body impacted by an EL3...
- I highly doubt this theory myself, but who are you or I to say that
they're not foreign objects? You stated your own lack of expertise in
your message, and I acknowledge my own here as well.


>It is very obvious to me that Al Haggounia 001 is an
EL Chondrite and with all E-Chondrites, there is a
close kinship to Aubrites.

Well, it has chondrules, but, again, I would not, by any means, settle
to calling it an EL3 - or an Aubrite. Structurally, it is neither.

Anomalous, anyone?

Regards,
Jason

On Dec 1, 2007 12:07 AM, Adam Hupe <raremeteorites at yahoo.com> wrote:
> Jason,
>
> I never called it a type three if you read my emails
> although I am confident with the designation
> scientists with decades of experience assigned it. I
> am certainly no expert on the degree of metamorphism
> determing petrologic types in chondrites so I will
> present some notes collected from various resources in
> regards to this meteorite.
>
> Not only is the object in earlier posted image an
> obvious chondrule, it is a very well-formed,
> sharp-edged radial pyroxene chondrule (with a clear
> annular rim) containing glass (now largely dissolved
> out), and this and others like it are the basis for
> the Type 3 designation, along with the fact that the
> matrix is not at all recrystallized but instead
> "primitive". Finally it is not the low abundance of
> chondrules that is important, but their form and glass
> content and the matrix texture as confirmed by several
> chondrite experts.
>
> As far is it being an Aubrite, there is the lack of a
> distinctive type of microstructure (polysynthetic
> twinning) in the enstatite grains in the Al Haggounia
> material, but which to my knowledge is present in all
> aubrites (because of their high temperature igneous
> history).
>
> Here is a link to the meteorites.tv site that has the
> clear definition of an Aubrite:
> http://www.meteorites.tv/index.html?lang=en-us&target=d281.html
>
> Finaly, the so-called f-clasts found in some real
> Aubrites are from brecciating impactors but this is
> not what we're talking about here. The chondrules
> found in Al Haggounia 001 are clealy native to the
> matrix and not from an impactor so this argument holds
> no water.
>
> It is very obvious to me that Al Haggounia 001 is an
> EL Chondrite and with all E-Chondrites, there is a
> close kinship to Aubrites.
>
>
> Best Regards,
>
> Adam
>
>
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Received on Sat 01 Dec 2007 06:24:20 AM PST