[meteorite-list] Fwd: getting oriented on orientation

From: Darryl Pitt <darryl_at_meteoritecentral.com>
Date: Wed, 5 Mar 2008 16:14:30 -0500
Message-ID: <1F1AFB63-2320-4B07-90F7-8AEF4BA17D4F_at_dof3.com>

as previously mentioned, some of the guidelines used to establish
orientation should be weighted more heavily than others.

when a stone is weathered, the only way to determine a high degree of
orientation would still be the reliance on the same conventions to
determine the extent of orientation.

for example....a highly weathered meteorite's morphology exhibits an
unmistakably curved parabolic surface, e.g., brenham main mass. of
course that should trump everything---the object is inarguably highly
oriented.

bottom line, if you can't discern for certain whether the specimen is
oriented per agreed upon guidelines, then you can't state the object
is oriented. it's that simple. ('tis frustrating to me when folks
mention that willamette is oriented. could have been. but it's
unverifiable. so it's not.)

in effect, what is implied with orientation is that if all of the
characteristics which denote orientation are weathered away, no
determination of orientation can or should be made on the most highly
weathered material. right?

all best / darryl



Begin forwarded message:

> From: "Dave Gheesling" <dave at fallingrocks.com>
> Date: March 5, 2008 3:23:19 PM EST
> To: <MeteorHntr at aol.com>, <fuzzfoot at comcast.net>,
> <darryl at dof3.com>, <meteorite-list at meteoritecentral.com>
> Subject: RE: [meteorite-list] getting oriented on orientation
> Reply-To: <dave at fallingrocks.com>
>
>
> Steve & List,
>
> I just sent the following to Darryl off line, as we've been
> discussing this
> issue with great interest, and thought I'd add it here because it
> coincidentally makes very similar points (we very much agree) but with
> perhaps a little different perspective:
>
> Darryl,
>
> Here are the problems, in my opinion, with the simplicity of that
> 0-1-2-3
> formula:
>
> First, freshness of the specimen can have a lot to do with several
> of the
> parameters, and just because a stone is weathered does not mean it's
> necessarily not "completely oriented."
>
> Second, a specimen's flight can be "completely oriented" but, due
> to the
> initial shape and composition of the meteoroid, it might not be a
> perfect
> nose cone. Frankly, again in my opinion, the object of much debate
> yesterday is "completely oriented" but was affected by these
> parameters
> (meaning largely by the second point and slightly by the first
> point, as it
> is very fresh but was obviously not picked up the day it fell). If
> you
> missed the extra photos, check this out:
>
> http://www.fallingrocks.com/Collections/NWAXXXb.htm
>
> I don't care what the final analysis is on this specimen, by the
> way, and am
> only using it as a frame of reference. If you saw that Kainsaz
> specimen
> (will link it below as well), even it introduces some interesting
> challenges
> to the "current working formula" though it is obviously "completely
> oriented":
>
> http://www.fallingrocks.com/Collections/Kainsaz.htm
>
> How one would provide for differentiation between this Kainsaz and,
> say,
> Lafayette based on a "completely" or "partially" oriented grading
> system, I
> am not sure. Layfayette is obviously fresher, has all sorts of
> flow lines
> and is a perfect dome, but they are both "completely oriented" in
> terms of
> flight and the resultant shape they both achieved.
>
> This will be fun to sort out, and I hope we get it to the finish line!
>
> Dave
>
>
> -----Original Message-----
> From: meteorite-list-bounces at meteoritecentral.com
> [mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of
> MeteorHntr at aol.com
> Sent: Wednesday, March 05, 2008 3:17 PM
> To: fuzzfoot at comcast.net; darryl at dof3.com;
> meteorite-list at meteoritecentral.com
> Subject: Re: [meteorite-list] getting oriented on orientation
>
> Hello Mike and all,
>
> Mike, I like your suggestion.
>
> Obviously, a large contributing factor in a the final shape of a
> meteorite,
>
> has to do with it's original shape of the rock before the fireball
> (or as
> it
> broke apart in flight). Some rocks are just destined to look
> better (more
> nosecone or shielded in shape) than others. But that gets more into
> subjective
> interpretation.
>
> One challenge is that composition and weathering can play a part
> in the
> appearance of a meteorite.
>
> The Brenham Main Mass, while few would argue is not oriented, does
> not have
>
> flow lines, or a roll over lip. The trailing side is noticeably
> more rough
>
> than the nosecone, as it was not melted, but there is not "frothy"
> evidence
> of
> bubbling on in the low pressure zones on the back side.
>
> So, while it would not have ALL 5 or 6 or 7 or 8 potential
> characteristics
> of being oriented, the evidence points that it indeed was 100%
> oriented in
> it's flight, thus producing the shape it is in now, less a bit of
> wathering.
> Also, I am not sure that a large pallasite would have the same
> ability as a
>
> Eucrite would have in displaying the different potential
> characteristics?
>
> So would the Big Brenham get a "lower grade" than a strange shaped
> Millbillillie that might have more characteristics, yet not look
> even close
> to what
> one thinks an oriented meteorite should be?
>
> I think there are some characteristics that lead to a definite
> conclusion
> that the rock did not tumble in flight.
>
> I think if a dealer, or collector wants to represent their meteorite
> specimen as oriented, they need to justify why they think it is,
> base on
> the
> accepted criteria. Then it is up to the observer/buyer to
> evaluate the
> quality of
> those characteristics.
>
> Not all flowlines are the same. Not all roll over lips are the
> same. Not
> all frothy crust on the trailing side is the same. Not all
> curvature of
> leading edge is the same.
>
> Are we going to then grade each charateristic on a scale of 1 to 5?
>
> A description might then look like this.
>
> "Based on the "IMCA 4-Point Scale of Orientation' this rock grades
> at a
> 2.25
> out of 5 as follows:
> Characteristic A: Flowlines Scale 1-5 = 4 note: flowlines over
> 60% of the
>
> rock All from a radiant point
> Characteristic B: Roll Over Lip Scale 1-5 = 2 note: Mild roll
> over lip on
>
> 25% of the edge
> Characteristic C: Parabolic Curve Scale 1-5 = 3 note: curvature is
> on a
> 280*
> curve on X axis, 264* on Y axis
> Characteristic D: Bubbling trailing side Scale 1-5 = 1 somewhat
> different
> texture on the back side
> Total 4+2+3+1 = 9 / 4 = 2.25"
>
> Or, you do like Mike Farmer mentioned, you call it oriented, and
> you supply
>
> 16 photographs to back up your point.
>
> Or, you say, like Mike suggested: O3, O2 or O1, Completely,
> Partially, or
> Some, and justify why.
>
> My two flowlines worth.
>
> Maybe we should set up a Crater grading scale while we are at it?
>
> Steve Arnold
> Arkansas
>
>
>
>
> .
> In a message dated 3/5/2008 11:17:41 A.M. Central Standard Time,
> fuzzfoot at comcast.net writes:
> Great suggestions, Darryl. I would go even a little less
> complicated and
> suggest a 3 number rating system. Here are some quick, nut-shell
> definitions:
>
> O3 - Completely oriented: Obvious and conclusive evidence that the
> meteorite
> stabilized during entire flight.
>
> O2 - Partially Oriented: Evidence that the meteorite stabilized
> during most
>
> of flight, but also tumbled of axis.
>
> O1 - Some Orientation: Evidence that the meteorite stabilized
> briefly at
> one
> or several different points during flight, but tumbled majority of
> flight.
>
> No Orientation - If no orientation is present, then there is
> probably no
> need to mention it in description.
>
> Other considerations: Where does 'dual orientation' fit in? I have
> had
> numerous Sikhotes that have had 'bullets' or 'buttons' on both ends -
> evidence
> that the they flopped like a pancake and partially stabilized on both
> opposing
> edges.
>
> Keep the suggestions coming.
>
> Best,
>
> Mike Bandli
> www.Astro-Artifacts.com
>
>
>
>
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Received on Wed 05 Mar 2008 04:14:30 PM PST