[meteorite-list] So Chelyabinsk is not an impact-melt meteorite. Steve said so

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Sun, 22 Feb 2015 23:49:57 -0500
Message-ID: <CAKBPJW-QXmuq4xreWYbVEEA3ua57grn8yyBoWQWt392+qgZmbw_at_mail.gmail.com>

>From the Met Bull entry on Chelyabinsk :

Petrography: (D.D. Badyukov and M.A. Nazarov, Vernad). The majority
(2/3) of the stones are composed of a light-colored lithology with a
typical chondritic texture. Chondrules (~63%) are readily delineated
and set within a fragmental matrix. The mean chondrule diameter is
0.93 mm. The chondrule glass is devitrified. The main phases are
olivine and orthopyroxene. Olivine shows mosaicism and planar
fractures. Rare grains of augite and clinobronzite are present. Small
and rare feldspar grains show undulatory extinction, planar
deformation features, and are partly isotropic. Troilite (4 vol.%) and
FeNi metal (1.3 vol.%) occur as irregularly shaped grains. Accessory
minerals are chromite, ilmenite, and Cl-apatite. A significant portion
(1/3) of the stones consist of a dark, fine-grained impact melt
containing mineral and chondrule fragments. Feldspar is well developed
and practically isotropic. No high-pressure phases were found in the
impact melt. There are black-colored thin shock veins in both light
and dark lithologies.

-----> A significant portion (1/3) of the stones consist of a dark,
fine-grained impact melt containing mineral and chondrule fragments.

Maybe Chelyabinsk is not classified as an LL5-melt-breccia because
parts of it are not, while the NWA LL5-melt-breccia sample is entirely
impact melt, so it was classified as such. If the only Chelyabinsk
classification sample had been a melt, then it would have been
classified as a melt.

Chegach is another example - it has well known melt stones, but it is
classified as H5, not H5-melt.

Best regards,

MikeG

PS - claiming "my meteorite is the only xxxxx" is just marketing based
on nomenclature. That NWA is not the only example of
LL5-melt-breccia, it's just the only one classified as such because of
a myriad of obtuse reasons, the least of which being it was found in
the NWA DCA, so the strewnfield was not mapped out properly where
non-melt stones could be paired to the original melt find to give a
more complete classification.

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On 2/22/15, Michael Farmer <mike at meteoriteguy.com> wrote:
> Steve and Quinn Arnold are telling us on Facebook that Chelyabinsk is not an
> impact-melt breccia, and that Tony Irving confirms that. Is that true? Funny
> when I google it, hundreds of papers discuss the metric ton of known
> Chelyabinsk as all being impact-melt material. Of course, those of us who
> went there and have a large amount of Chelyabinsk can tell you that it sure
> seem full of clasts, and melt pockets and shock veins. Since his kickstarter
> rock seems to be the only known LL5 melt (according to the (met. Bull.)and
> Chelyabinsk seems to be nothing of the sort, it is amazing to me.
> Comments? Anyone in this list, scientist or collector know something I
> don't, that Chelyabinsk is a "non" impact-melt meteorite?
> Micael Farmer
>
>> On Feb 22, 2015, at 10:07 AM, Galactic Stone & Ironworks via
>> Meteorite-list <meteorite-list at meteoritecentral.com> wrote:
>>
>> Hi Bulletin Watchers,
>>
>> There are 13 new approvals from around the world.  One of the
>> approvals is a lunar and several are melts.
>>
>> Link :
>> http://www.lpi.usra.edu/meteor/metbull.php?sea=%2A&sfor=names&ants=&falls=&valids=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&categ=All&mblist=All&rect=&phot=&snew=2&pnt=Normal%20table&dr=&page=0
>>
>> Best regards and Happy Huntings,
>>
>> MikeG
>>
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Received on Sun 22 Feb 2015 11:49:57 PM PST