[meteorite-list] More petrographic questions.

From: David Weir <dweir_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:08 2004
Message-ID: <3A85D152.734C0D82_at_cegi.net>

Hello Steve,

Is there a need to add another number higher than 6 before calling a
meteorite an achondrite? Said another way, why draw a line someplace
where the metamorphism suddenly becomes a 7? This delineation is defined
as the complete lack of chondrules? Why isn't this an achondrite? And do
we even have enough of the parent rock to say for sure that there are no
chondrules? As you mentioned, look at the achondrite (acapulcoite)
Tissemoumine with definite chondrules, or even those relict chondrules
in Monument Draw. Doesn't this blur the delineation between chondrite
and achondrite, and petrologic 6 and 7? Perhaps the classificational
terms chondrite and achondrite should be abandoned as generalized
grouping terms. I'll be waiting for some answers.

David
Received on Sat 10 Feb 2001 06:40:02 PM PST