[meteorite-list] monomict - genomict - polymict

[bernd.pauli at paulinet.de]

Steve Arnold wrote: 

"I have seen with many eucrites that there is a polymict
 type and a monomict type. What are the differences? 

Geoff responded:

"Dear Steve: May I recommend a very useful resource
 to you: The Cambridge Encyclopedia of Meteorites"


Hello All,

On page 344 of the glossary, we find:

monomict breccia:

A brecciated meteorite composed of angular
fragments and matrix all of like composition

On page 345 of the glossary, we find:

polymict breccia:
A rock made up of angular fragments or clasts
from other rocks of different compositions

On page 343 of the glossary, we find:

genomict breccia:

A brecciated meteorite in which the individual clasts are compositionally
of the same group but have differing petrographic characteristics

Wasson puts it this way:

WASSON J.T. (1974) Meteorites Classification and Properties
(Springer-Verlag, Berlin,  Heidelberg, New York, Appendix I,
Glossary, p. 242):

Breccia:

A fragmental rock type including components (the larger pieces called
xenoliths or clasts) which were previously part of another rock. In a
*monomict* breccia all components originated in the same rock; in a
*genomict* breccia the components originated in distinct but genetically
closely related rocks; in *polymict* breccias the components originated
in two or more unrelated rocks.

Cheers,

Bernd