[meteorite-list] Largest Carbonaceous Meteorites

From: Jeffrey N. Grossman <jgrossman_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:11 2004
Message-ID: <4.3.2.7.2.20010221122539.025f4738_at_127.0.0.1>

Meteorites from dense collection areas all get individual numbers. The=20
proper collective term for the DaG CO3's is "The Dar al Gani 005 pairing=20
group," named after the first-described or lowest-numbered one (actually,=20
one might argue that this could be DaG 006, but it doesn't really matter).

I don't believe that anybody has published the metamorphic subtype of the=20
DaG 005 group. These subtypes, ranging from 3.0-3.9, are widely accepted=20
for use with H-L-LL3 and CO3 chondrites. They are defined on the basis of=
=20
a combination of petrographic, mineral-chemical, and bulk-chemical data,=20
and induced thermoluminescence (TL) sensitivity. They have also been=20
defined by TL for CV3 chondrites, but those are not widely used. They=20
represent increasing degrees of thermal metamorphism.

It seems to me that an interesting question about the largest C chondrite=20
(or any other class) is not necessarily the total mass of the fall, but the=
=20
largest individual mass that survives. Anybody know what this is? It=20
would be hard to prove that the 1000's of pieces of DaG 749 did not break=20
apart on impact, so you can't really count this as a 95 kg stone. The=20
largest single piece is 25.1 kg. The largest Allende stones described by=
=20
Clarke (1970), including one 100-110 kg, one 40-50 kg, and one 35 kg, all=20
broke upon impact; only those in the <20 kg range survived intact. There=
=20
was a 47 kg Lanc=E9 specimen, but I don't know if it landed whole. However,=
=20
apparently there was a 102.5 kg Kainsaz stone that made it in one=20
piece. There's a photo of it in the 1938 Nature article by Selivanov, who=
=20
says it's "very well preserved." This is now in Moscow. Unless somebody=20
knows of another candidate, I'd say this is the world champion carbonaceous=
=20
chondrite specimen.

-jeff

At 11:53 AM 2/21/2001, Frank Cressy wrote:
>Thank you Michel, Ron and Bernd,
>
>Looks like Murchison gets bumped to number 4 on the largest carbonaceous
>chondrite list with number 3 being DaG 749 and other paired DaG's totaling
>177 Kg. The confusion lies in the fact that several numbered DaG's are
>listed from this CO3 strewnfield. Any possibility that the nomenclature
>committee can grant one name for this find and list the other names as
>synonyms? Just a thought.
>Thanks again,
> Frank
>
>
>
>
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Dr. Jeffrey N. Grossman phone: (703) 648-6184
US Geological Survey fax: (703) 648-6383
954 National Center
Reston, VA 20192, USA
Received on Wed 21 Feb 2001 03:07:43 PM PST