[meteorite-list] Hyphens / Slashes

From: bernd.pauli_at_paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:52 2004
Message-ID: <DIIE.0000003E00001C59_at_paulinet.de>

> For chondrite groups, petrologic types, shock stages, and weathering
> grades, slashes (e.g., H5/6) indicate transitional assignments. Hyphens
> in petrologic type assignments for chondrites (e.g., H5-6) indicate the
> range of types observed in breccias. Group names such as "L(LL)" indicate
> uncertain assignments, with the less probable group in parentheses.

Hello All,

I was waiting for Jeff Grossman to chime in here, because
on Monday, 07 Sep 1998, Jeff wrote to this to the List (excerpts):

Right now we have a literature polluted with this and other nomenclatures
(like using a "/" instead of a "-" for the same thing), and the community has
no way of looking at a catalog and knowing what's what. The Meteorite
Nomenclature committee has no jurisdiction over meteorite classification;
it just oversees meteorite names. It's just a mess.

There is NO convention for naming brecciated chondrites. Many, including the
group at Muenster, like to use a slash to separate components of a breccia.
However, nobody has ever written a paper on the subject, and the rules are up
for grabs. I happen to be of the opinion that the slash is ridiculous for many reasons,
including the one brought up here: we will always need to be reclassifying breccias
whenever somebody finds a new lithology among the clasts. This is not feasible.

These parentheses are used by some researchers when they cannot determine with
certainty the group assignment of a meteorite. L(LL)3 means that they lean towards
L3, but it could be an LL3. Indeed, it is very difficult to differentiate between L3 and LL3
chondrites, as they may have similar sized chondrules, similar metallography, similar
silicate compositions (i.e., highly heterogeneous), and even oxygen isotope compositions
and trace elements cannot always resolve them well. Even some of the most famous, best
studied meteorites have been given various classifications in different parts of the literature
(e.g., Tieschitz, Krymka, Bishunpur).

If any meteorite has been called "LL/(L)3", I have no clue what this means.

To: dgweir_at_earthlink.net
Cc: meteorite-list_at_meteoritecentral.com
Received on Fri 19 Mar 2004 02:55:47 PM PST

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