[meteorite-list] Met Bulletin Update - EL's and OC's

From: Jim Wooddell <jimwooddell_at_meteoritecentral.com>
Date: Sun, 17 Feb 2013 18:21:07 -0700
Message-ID: <CAH_zgwGeQGOkXH5wasOFpsLRUNj9=f05Shy4H45ok4RKt4Qh8w_at_mail.gmail.com>

Hi Mendy,

I can give you one perfect example (with reasonable certainty) exactly
 what Alan stated where "certainty is lower".

Pairing is or can be much more involved than one might think, frm what
 I've learned.

So I like my rule number 38: NEVER assume the meteorite in your hand
 is what you think it is, unless it's a scientifically derived
 conclusion.

Cheers!

Jim

On Sun, Feb 17, 2013 at 4:34 PM, Alan Rubin <aerubin at ucla.edu> wrote:
> If specimens are part of an observed fall and are very fresh looking, one
> supposes (without absolute certainty) that the different individuals are
> paired. If stones are found lying on the ground in an area that has yielded
> few other meteorites, then one can also assume that they are paired, but the
> certainty is lower. The probability can increase, however, if they are of a
> rare type. But if stones are found in a region where there are overlapping
> strewnfields or if some concentration mechanism has brought different
> meteorites together, then we are less certain that they are paired even if
> they are of an unusual type. We may say that they are probably paired
> (particularly if they have similar textures, bulk compositions, terrestrial
> ages, cosmic-ray expsosure ages, etc.), but the prudent thing to do (since
> we generally don't have all of these data) is to treat them as separate
> meteorites with separate numbers and let the pairing be a scientifically
> derived conclusion, not a curatorial assignment.
>
>
> 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: "Mendy Ouzillou" <ouzillou at yahoo.com>
> To: "'Robert Verish'" <bolidechaser at yahoo.com>; "'Jeff Grossman'"
> <jngrossman at gmail.com>; <meteorite-list at meteoritecentral.com>
> Sent: Sunday, February 17, 2013 3:13 PM
>
> Subject: Re: [meteorite-list] Met Bulletin Update - EL's and OC's
>
>
> Bob,
> Sorry it took me so long to respond - the email got buried under a Russian
> meteorite.
> Your explanation is logical, but the classifiers did not mention these two
> stones as being paired. Seeing as these were very likely found close to each
> other (but perhaps subjected to different weathering conditions) they should
> at a minimum be stated as paired. I know it is impossible to prevent the
> explosion of numbers assigned for the reasons you stated below - I get that,
> but at what point does it become too burdensome (rhetorical question)? How
> do scientists know what numbers are paired together if the two
> classifications do not state it that way (not rhetorical)?
> Best,
> Mendy
>
> -----Original Message-----
> From: Robert Verish [mailto:bolidechaser at yahoo.com]
> Sent: Sunday, February 17, 2013 1:02 AM
> To: 'Jeff Grossman'; meteorite-list at meteoritecentral.com; Mendy Ouzillou
> Subject: Re: [meteorite-list] Met Bulletin Update - EL's and OC's
>
> One benefit of having two numbers is that it allows the classifier to
> clarify the differences between the two stones in order to show the range of
> variation among these paired EL stones. The difference in this case being
> one stone has "Alabandite present", and the second stone was "Extremely
> weathered showing only rare metal. Rare alabandite".
>
> This would actually aid a subsequent classifier of another EL6 stone to be
> able to pair that third stone to the other two. Otherwise that subsequent
> classifier (not being aware of this variation) may be misled into thinking
> that the third stone is unpaired.
>
> When I first read Mendy's question about "assignment of NWA numbers", I
> thought he was making reference to assignment of provisional numbers. These
> are usually assigned before the stones are classified and if the stones have
> any appearance of outwardly looking different to each other, the prudent
> requester is wise to get a number for each stone.
>
> Once a requester gets two numbers "assigned", it's not likely that a
> classifier will get rid of one number. Where is the motivation if the
> classifier will get more type-specimen by having each stone numbered.
>
> If the classifier submits a classification for each numbered stone, the
> NomCom will accommodate that classifier by "approving" both numbers.
> Anything less, and the NomCom would be considered "unaccommodating".
>
> Now, in defense of the classifier for not getting rid of one of the numbers,
> I would say that the test lies in answering this question:
> "What is the added-value in discarding a number?"
> (Which is basically what Jeff Grossman was saying when he asked, "Why is
> this a problem?")
>
> Or stated another way:
> "Is there any added-value in approving two numbers that were assigned to two
> stones that were subsequently paired?"
>
> For one answer to that question as it relates to these two EL6 stones, go to
> the beginning of this post.
>
> Bob V.
>
>
> --- On Sat, 2/16/13, Mendy Ouzillou <ouzillou at yahoo.com> wrote:
>
>> From: Mendy Ouzillou <ouzillou at yahoo.com>
>> Subject: Re: [meteorite-list] Met Bulletin Update - EL's and OC's
>> To: "'Jeff Grossman'" <jngrossman at gmail.com>,
>> meteorite-list at meteoritecentral.com
>> Date: Saturday, February 16, 2013, 8:51 PM
>>
>> Because as I read it
>> the data for both specimens are the same within the margin of error
>> and the two specimens should share one number.
>>
>> M
>>
>> -----Original Message-----
>> From: meteorite-list-bounces at meteoritecentral.com
>> [mailto:meteorite-list-bounces at meteoritecentral.com]
>> On Behalf Of Jeff Grossman
>> Sent: Saturday, February 16, 2013 7:24 PM
>> To: meteorite-list at meteoritecentral.com
>> Subject: Re: [meteorite-list] Met Bulletin Update - EL's and OC's
>>
>> Why is this a problem? -jeff
>>
>> On 2/16/2013 9:46 PM, Mendy Ouzillou wrote:
>> > Why are two consecutive numbers assigned to the same
>> group of stones.
>> EL6, two stones and same classifiers. I don't get it ...
>> >
>> > Mendy Ouzillou
>> >
>> > On Feb 16, 2013, at 10:20 AM, "Galactic Stone &
>> Ironworks" <meteoritemike at gmail.com> wrote:
>> >
>> > Hi Bulletin Watchers,
>> >
>> > There are a handful of new approvals - all are NWA meteorites.
>> >
>> > Link -
>> http://www.lpi.usra.edu/meteor/metbull.php?sea=&sfor=names&ants=&falls
>> =&valids=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&c
>> ateg=All&mblist=All&rect=&phot=&snew=1&pnt=Normal%20table&dr=&page=0
>> >
>> > Best regards,
>> >
>> > MikeG
>> >
>>
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-- 
Jim Wooddell
jimwooddell at gmail.com
928-247-2675

Received on Sun 17 Feb 2013 08:21:07 PM PST