[meteorite-list] Never underestimate or dismiss Spectroscopy

From: MstrEman <mstreman_at_meteoritecentral.com>
Date: Fri, 18 May 2012 05:11:18 -0400
Message-ID: <CAPwdm9FCL3Y2qs9bALP6J8VMD7gwH+bBgiubxnsqQtd-fmTGrg_at_mail.gmail.com>

Dear Benjamin, I can see your argument and I got you point of
preference but I don't get the resistance to accepting the facts
regarding the current scheme of meteorite classification or the
parallel field of parent bodies. I've already said several times when
it is considered correct to connect HED clan meteorites to Vesta but
there are 2 (count'em 2) simple caveats.

 Maybe you knew but I am not sure the rest of the list knew that we've
some non Vestian Eucrites. I am not sure that the other folks also
know of the large number of Vesta Family asteroids which could also
have delivered meteorites to our orbit. Belaboring the point that I
should have addressed earlier, Vesta's present orbit may or may not be
able to deliver HED's directly to Earth. I defer to those who
calculate orbital mechanics to say when or if. Some asteroids cannot
send samples our way or so I have been told, yet, we have been able to
classify them via spectra. One of those wee far flung fragments is
spectraly identical to the Vesta family(IIRC) but owing to some
analysis it can't be apart of the Vesta system:never was and it can't
deliver samples here to Earth. Collectors won't find that interesting
but planetary scientist might theorize that there were several
proto-planets/planetesimals which reached an eerily similar stage of
development then stopped and that would keep them occupied long into
their PhD.s

 As for grouping it isn't as simplistic as you advocate. I don't make
the rules so "I" don't "group" meteorites-- that is for the Non-Com, I
believe and whatever the past use of the word "eucrite" it doesn't
apply to the meteorite classification in use but thanks for the
trivia. I understand by convention, it takes a minimum of three
examples to establish a group in any of our meteorite classifications
but that has not been strictly applied to Lunars and most Martians.
There we allow chemistry and fabric to suffice as sub descriptors
because frankly there is more variability than the HEDs show.
However, this is a moot point because eucrites are not classified as
"anomalous" and agreed maybe they should be to differentiate (no pun)
origins.

 We had this discussion you and I but it bears repeating. Eucrite
mono/poly mict is a classification based on a specific rock texture
and says nothing as to origin parent body but, everything as to where
within a given body it originated. Under your theory of
classification by origin , we could have hundreds of groups based
common parent body origins of common chondrites. Instead we classify
them on the basis of mineralogy, metal content, matrix, and degree of
metamorphism. Martins are based on origin along with
sub-classification as to rock texture as in SNC and ditto with Lunars.
 They are true planetary bodies and show a more diversified geology.
So stand by for Veneusian and Mercurian the VENs and MERCs at a
Non-Com near you.

We know that all mesosiderites come from 2(or 3) commingled parent
bodies but mesosiderite isn't an "origin based" classification. When
we do find an meso-outlyer will we call it anomalous? I don't know--
ask the Non-Com how they will rule.

Classification has migrated into new schemes as the tools of science
advance and maybe some day there will be a renaming of "eucrites" to
reflect an origin other than 4 Vesta. You are more than welcome to
describe your Eucrite as from Vesta but in the planetary science we
understand that each body liberated from Vesta proper has its own
impact and thermal histories and this may someday reveal more about
the history of the solar system. Someday we will have a catalog of
each's mineralogy and in depth. Meanwhile we modify our nomenclature
to match our understanding. Today all I am asking ..well sharing is
that what we've always heard about HEDs and Vesta technically are not
accurate or or non-proven but close enough for government work as the
cliche` goes.

My points were it is generally acceptable amongst collectors to refer
to Vesta as the source of HEDs but to the researcher it is not, unless
everyone in the discussion understands the caveats aforementioned. I
realize everyone is not here for the technical side but at the time I
felt it worth mentioning in a side note that all Eucrites are NOT from
Vesta. And those that aren't are pretty darn interesting in and of
themselves.

Elton

On 5/16/12, Benjamin P. Sun <bpsun2009 at gmail.com> wrote:
> If a dealer or someone were to claim that their Tatahouine or NWA 2060
> came from Vesta, I would not counter or argue with him.
>
Received on Fri 18 May 2012 05:11:18 AM PDT