[meteorite-list] Ungrouped Achondrite Prices (NWA 7325 andothers)

From: Alan Rubin <aerubin_at_meteoritecentral.com>
Date: Wed, 12 Mar 2014 22:00:50 -0700
Message-ID: <71D86ECA392C4AF99D06D17E9C600717_at_igpp.ucla.edu>

Almost all CKs are type 4-6; all CVs are type 3. The few CK3s seem to be
CK3/4 or CK3.8 or so. In fact, the only way to recognize a meteorite as CK
at all is if it is sufficiently metamorphosed to have many of the olivines
equilibrated. If not, the rock will be classified as a CV. Since many of
the CK4s and the few CK3s I looked crushed and fragmental, and that many CKs
are shocked (which I showed back in 92), then it seems to me that impacts
are the means of transforming a CV3 to a CK. Because CKs are oxidized, they
clearly are not being made from reduced CVs like Vigarano, Efremovka and
Leoville. Because many of the Bali oxidized subgroup have strong
petrofabrics and CKs don't then the CKs are either being made from the
Allende oxidized subgroup or from a third, heretofore unsampled, oxidized CV
subgroup. Anyway, we recommended dropping the CK designation altogether
(i.e., call rocks CV3, CV4, CV5, CV6), although the CK designation is so
entrenched by this point, that I doubt that this will happen.
So, with this background, you could call it a CV-CK parent body, or simply
just a CV parent body. One final point, how many CV or CV-CK parent bodies
are there? We don't know tha answer to that question for any chondrite
group. There may be only one of some groups represented in our collections,
or there may be several. (Nearly half of the H chondrites have the same CRE
age of about 7.6 Ma), so these samples were all on the same parent body at
that time. Other samples may have been on other H chondrite parent bodies
or at distant locations on the same parent body. We don't know. But since
asteroids tend to b reak into smaller bodies via a collisional cascade, it
may well be that by the time the collision occurred that gave us half of the
H chondrites, the original parent H chondrfite asteroid had already been
broken into several chunks, only one of which was struck at that time. The
same may be true for many kinds of meteorites.)
Alan

Alan Rubin
Institute of Geophysics and Planetary Physics
University of California
3845 Slichter Hall
603 Charles Young Dr. E
Los Angeles, CA 90095-1567
phone: 310-825-3202
e-mail: aerubin at ucla.edu
website: http://cosmochemists.igpp.ucla.edu/Rubin.html


----- Original Message -----
From: "Carl Agee" <agee at unm.edu>
To: "Alan Rubin" <aerubin at ucla.edu>
Cc: "Galactic Stone & Ironworks" <meteoritemike at gmail.com>; "Meteorite List"
<meteorite-list at meteoritecentral.com>
Sent: Wednesday, March 12, 2014 9:35 PM
Subject: Re: [meteorite-list] Ungrouped Achondrite Prices (NWA 7325
andothers)


> Alan,
>
> Thanks, you just saved me from a savaging by reviewers of my paper
> still "in prep"! I guess CK 'precursor' is a safer term than 'parent
> body'? Or are we calling it the CV-CK parent body? (with the UCLA good
> housekeeping seal of approval). I'm happy with just melting a CV, I
> used to do that all the time in the lab, except at very high pressure.
>
> Carl
> *************************************
> Carl B. Agee
> Director and Curator, Institute of Meteoritics
> Professor, Earth and Planetary Sciences
> MSC03 2050
> University of New Mexico
> Albuquerque NM 87131-1126
>
> Tel: (505) 750-7172
> Fax: (505) 277-3577
> Email: agee at unm.edu
> http://meteorite.unm.edu/people/carl_agee/
>
>
>
> On Wed, Mar 12, 2014 at 10:26 PM, Alan Rubin <aerubin at ucla.edu> wrote:
>> Carl mentioned "a CK parent body." I doubt that there is such a thing.
>> In
>> a recent paper, the UCLA folks suggested that CKs were just metamorphosed
>> CVs. I wrote a column in Meteorite about that not too long ago as well.
>> If
>> this is correct then a CK parent body would really likely be a CV-CK
>> parent
>> body. Carl's idea then becomes a little more complicated. Either you
>> have
>> to make the achondrite straight from a CV or you have to metamorphose the
>> CV
>> material (perhaps by collisions, perhaps by slow heating via 26Al) to
>> make a
>> CK and then melt that. It seems simpler to skip the CK step.
>> Alan
>>
>>
>> Alan Rubin
>> Institute of Geophysics and Planetary Physics
>> University of California
>> 3845 Slichter Hall
>> 603 Charles Young Dr. E
>> Los Angeles, CA 90095-1567
>> phone: 310-825-3202
>> e-mail: aerubin at ucla.edu
>> website: http://cosmochemists.igpp.ucla.edu/Rubin.html
>>
>>
>> ----- Original Message ----- From: "Carl Agee" <agee at unm.edu>
>> To: "Galactic Stone & Ironworks" <meteoritemike at gmail.com>
>> Cc: "Meteorite List" <meteorite-list at meteoritecentral.com>
>> Sent: Wednesday, March 12, 2014 9:06 PM
>> Subject: Re: [meteorite-list] Ungrouped Achondrite Prices (NWA 7325
>> andothers)
>>
>>
>>
>>> Hi Mike and All:
>>>
>>> "Achondrite-ung" one of my favorite things! Also the enigmatic
>>> groupings like ACA, LOD, WIN, BRAC, URE, fascinating! From what I have
>>> seen and heard about NWA 7325 -- simply amazing. The problem has
>>> nothing to do with these wonderful achondrites, the problem is our
>>> ignorance of their possible parent bodies. Martian and lunar
>>> meteorites are of the highest scientific value, not because they are
>>> better meteorites, but because we know enough about their parent
>>> bodies to make the meteorite - parent body connection and thereby they
>>> become the equivalent of geological sample returns. If NASA hadn't
>>> sent missions to the Moon or Mars we would most likely not recognize
>>> these meteorites as lunar and Martian. So, the problem with Mercurian
>>> meteorites is not whether they do or don't exist, the problem is our
>>> fragmentary understanding of the planet Mercury and our inability, at
>>> this time, to make the parent body - meteorite connection. Yes,
>>> Mercury Messenger has given us new insight into the make up of the
>>> Mercurian crust, but the data are simply still not good enough to be
>>> useful for unequivocal meteorite matching. So even if we have a
>>> meteorite from Mercury somewhere in the world's collections right now,
>>> we won't know it until Mercury is better known. Part of the problem is
>>> that Mercury possesses no true atmosphere. Remember, the strongest
>>> evidence for martian meteorites being from Mars is trapped martian
>>> atmospheric gases in the meteorites -- the ultimate fingerprint.
>>> Interestingly, we may have a better shot at recognizing a meteorite
>>> from Venus, since the Venusian atmosphere has been geochemically and
>>> isotopically measured by NASA missions and spectroscopically from
>>> Earth. For example, trapped Venusian atmosphere should have a
>>> gigantically large ratio of deuterium to hydrogen. In the meantime,
>>> there are other ways to think about parent bodies of achondrites --
>>> identifying their meteoritic precursor material. For example, I
>>> recently worked on achondrite-ung NWA 8186 that appears to be the
>>> first example of an achondrite that is a very good match for having a
>>> CK-chondrite precursor -- in other words, take a CK parent body,
>>> igneously melt it, and the product is achondrite-ung NWA 8186. Hey,
>>> who said the list was boring? Mike, great discussion topic!
>>>
>>> Carl Agee
>>>
>>> *************************************
>>> Carl B. Agee
>>> Director and Curator, Institute of Meteoritics
>>> Professor, Earth and Planetary Sciences
>>> MSC03 2050
>>> University of New Mexico
>>> Albuquerque NM 87131-1126
>>>
>>> Tel: (505) 750-7172
>>> Fax: (505) 277-3577
>>> Email: agee at unm.edu
>>> http://meteorite.unm.edu/people/carl_agee/
>>>
>>>
>>>
>>> On Wed, Mar 12, 2014 at 6:29 PM, Galactic Stone & Ironworks
>>> <meteoritemike at gmail.com> wrote:
>>>>
>>>> Hi Listees,
>>>>
>>>> Can someone elaborate on why NWA 7325 and it's possible pairings are
>>>> selling for $10,000/g in some cases? There is speculation that it
>>>> originated from Mercury, but that is only speculation at this point.
>>>> One can speculate anything. Heck, it might be from Alpha Centauri.
>>>>
>>>> There are 60 other ungrouped achondrites and some of them have very
>>>> unusual characteristics. Why is NWA 7325 priced so high above the
>>>> others? The low-TKW does not explain the price (maybe in small part),
>>>> given the fact that pairings appear to be surfacing.
>>>>
>>>> This is not a criticism of any dealer or dealers. I am just curious
>>>> how people have arrived at this price.
>>>>
>>>> Best regards,
>>>>
>>>> MikeG
>>>>
>>>>
>>>> --
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>>
>>
Received on Thu 13 Mar 2014 01:00:50 AM PDT