AW: [meteorite-list] Anomalous and Ungrouped Ordinary Chondrites

From: j.divelbiss_at_att.net <j.divelbiss_at_meteoritecentral.com>
Date: Thu Apr 22 10:28:32 2004
Message-ID: <101920032319.27758.434b_at_att.net>

Norbert,

I didn't read your comment very closely. It looks like you are saying it
takes 5 samples to make a group. Where does that criteria come from? I know
you are involved with the Society...so maybe there are known guidelines after
all. thanx in advance.

John

> Hi John, and list,
>
> As to the ungrouped HaH 180, and Deakin 001, it has been suggested
> that both represent samples of a new and previously unsampled parent
> body. If that holds to be true, they will never get a LL or L
> classification. Ungrouped just means that a sample can't be
> assigned to any of the established groups, and that means also
> that they do most probably represent a unique parent body. Now,
> if we find three more meteorites like HaH 180, or Deakin 001,
> scientists will most likely create a new group, and then these
> samples won't be ungrouped, any longer.
>
> The term "anomalous" is used for meteorites that actually can be
> assigned to an existing group, but that differ in some aspects from
> the other known members of that group. Thus, HaH 180 isn't anomalous,
> it's simply ungrouped.
>
> Short: an ungrouped chondrite most probably stems from an asteroid
> that hasn't been sampled so far. An anomalous LL, for example, is
> most probably from the LL parent body/asteroid, but it differs from

> the other LL members in some respect. The petrologic grades have
> nothing to do with that, and of course an ungrouped chondrite can
> be a 3.5, or a plain 6.
>
> Hope this helps ;-)
>
> Best,
> Norbert
>
> A puzzled John wrote:
>
> > Hello all,
> >
> > I've always been intrigued but puzzled about the classification of a few
> > ordinary chondrites into the black hole of assigned classification
> > names...ungrouped and/or anomalous. Some are specified with petrologic
> > assignments and others without. Ebay on occasion offers us Hah
> > 180 that is classified as an anomalous 3.5 ordinary chondrite and
> > Dhofar 535 that is classified as ungrouped, and without a petrologic
> > designation in its' description. According to David's site below...Hah
> > 180 is similar to Deakin 001. And there maybe others I am not thinking
> > of. Oxygen isotopes and weathering seem to be some of the key factors...
> > and as stated on David's site they may come from a proximity close to
> > where enstatite chondrites were formed, and in my opinion their appearance
> > makes them at least look like some of the EL3's out there.
> >
> > Does anyone know what the latest theory is for these and will
> > they one day
> > get an official LL3 to 3.5 anomalous label which would finally
> > give them a
> > home? Seems to me to call them anything else puts them/keeps them in
> > classification limbo.
>
Received on Sun 19 Oct 2003 07:19:25 PM PDT