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Re: A new LL7 from Austrailia.
Martin,
I think our collections would be a good place to find more type
7's. I feel that the type 7 designation is not a valid type so to speak.
Instead of representing a set of descrete principles, it merely indicates
an extreme metemorphism. I use the term on the basis of the olivines and
pyroxenes having almost the same Fe composition.
In addition, this one shows a shock classificsation of
stage 4. Perhaps it is greater, but some detail is obscured by
weathering.
This chondrite is unique, and displays some interesting
characteristics, for example, it contains a high plagioclase abundance.
If this were a eucrite, lunar, SNC, or angrite I would not be surprised
at seeing plagioclase in the meteorite. However, all other compositions
indicate a chondrite.
What Iam saying is, that if we were to look at these meteorites
more closely, perhaps a set of characters could be obtained to define the
type 7's more clearly. Maybe plagioclase is a result of melting of
olivine and pyroxene. I don't know. I am going to refine my elemental
abundances, and look for interesting relationships. I also would like to
contact the other folks who have designated type 7's. I think maybe it
could one day be used as a meaningful type designation.
Frank Stroik
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