[meteorite-list] RePallasites

From: Steve Schoner <schoner_at_meteoritecentral.com>
Date: Wed, 9 Sep 2009 17:05:43 GMT
Message-ID: <20090909.110543.15995.0_at_webmail17.dca.untd.com>

Hello all,

I spent nearly 2 decades searching Glorieta for the elusive pallasite mass that my friend, Harvey Nininger thought was still buried out there. The original article put out by Kunz in 1885 indicated that a pallasitic mass of about 40 to 60 lbs existed as it was missing from the three main iron masses recovered in that year or the year before. One side of the three assembled irons had a pallasitic side where the pallasitic mass was missing.

My focus was in the very rough terrain to the north of Apache Canyon, and toward Glorieta Mountain. The story of that has been documented in the 2001 issue of Meteorite magazine. I found many small pallasites in the hills and mountains to the north.

And after thousands of miles of searching, I found a 20 kg Glorieta pallasite. The very thing I had been seeking for near 20 years, and to date the largest one found. And I found it in a spot that I had never searched before, way off of the area where I had searched previously, and in 15 minutes into my search with a new Wilson detector.

Now in looking at some of the larger masses found after at Glorieta, I think that the meteoroid was a breccia. These club shaped irons are like the slabs of iron found in the Portales H6 meteorite. I think that in the cosmic history of Glorieta meteoroid, that there must have been a catastrophic impact that disrupted the pallasitic body, melting the iron, and fracturing the olivine crystals. The impacted mass then re-formed, the metal recrystallized, and the parent meteoroid re-constituted.

Entering the atmosphere in about 1250 AD, it then disrupted at high altitude, and that first disruption was along the pallasitic areas of the meteoroid. The solid slab and club shaped irons continued in flight, and the disrupted pallasitic masses fell first, scattering to the north and west of the larger solid irons. Most of the pallasites are small, usually only a few grams, and a few have been found that are in the kilogram range, the largest being 20 kg which I found in 1997.

I think that the original pallasitic parent body was disrupted billions of years ago in massive impacts. Glorieta has unusual olivine crystals that show fracturing most likely caused by disruption. Brenham and Springwater on the other hand show fairly distinct olivine crystals with little evidence of violent disruption. These might be more indicative of the pallasitic core.

Glorieta, a Rokicky group pallasite, shows evidence of cosmic disruption with fractured olivine crystals, and splinters and slabs of solid iron, all of which was again disrupted upon entry into the earth;s atmosphere.

BTW: In 1990 I found a spectacular olivine crystal, over 1 inch in size, crystal clear and gem quality. Put it in my pocket only to find later in the day that it fell through a hole. So somewhere to the north of Apache Canyon lies a nice gem quality Glorieta meteorite crystal.

Hope that the above is understandable, as I have some difficulty putting my thoughts into words, and also my broken left index finger does not help in typing.

Steve Schoner
IMCA #4470

 




Message: 6
Date: Tue, 8 Sep 2009 20:57:27 -0700
From: Jason Utas <meteoritekid at gmail.com>
Subject: Re: [meteorite-list] RePallasites
To: Meteorite-list <meteorite-list at meteoritecentral.com>
Message-ID:
        <93aaac890909082057v43ae617ey18eb74e82a4608de at mail.gmail.com>
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Hello Pete,
I'm not as well-versed in the science of such things as many on the
list, but I would point out that there are many multi-kg specimens of
Brenham that are composed entirely of iron. Other good examples of
similar features occurring in meteorites including, but not limited


to, Seymchan, initially mis-classified as a IIE iron because no
olivine was observed in the first pieces discovered, as well as the
Glorieta Mountain pallasite - the main mass was, from what I've heard,
was 100% nickel-iron, with some troilite and schreibersite inclusions.

Well, have a look:

http://www.nyrockman.com/auction-2008/lots/seymchan3376g.htm

http://www.meteoritefinder.com/catalog/glorieta-col-947.htm

http://www.meteoritefinder.com/collection/glorieta-101.7.htm

http://www.meteoritefinder.com/collection/glorieta-175.6.htm

To that end, I believe it's safe to say that the spacing of the
olivine crystals has noting to do with distance from the core.
Regards,
Jason


On Tue, Sep 8, 2009 at 8:26 PM, Pete Shugar<pshugar at clearwire.net> wrote:
> Hello list,
> I have a question.
> I have a piece of Brenham, Ks. It has very slim metal dividers that seperate
> the Olivine crystal pockets.
> There are other Pallasites that have much thicker metal dividers with
> smaller
> Olivine pockets.
> The question----would the former be formed further from the core than the
> latter?
> In other words, are there differences in the Olivine/Ni-Fe ratio if the
> meteorite
> comes from the area closer to the core or further away from the core per a
> cubic
> meter quantity of each.
> Pete IMCA 1733


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Received on Wed 09 Sep 2009 01:05:43 PM PDT