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Eric,
        I don't agree on possible confusion with a rock rich in pyribole.
Metamafite is too uninformative. Pyroxene amphibolite is a misnomer for
rocks in which pyroxene predominates over amphibole, as is so commonly the
case in high-grade terranes. BTW, it's pyriclasite - a term I personally
don't like much and haven't felt the need to use.
Tom
> Tom,
>     I do not like the term.  It certainly would be confused with the
> mineral group "pyribole", which I think was coined by Jim tompson in the
> 60's.  Feldspar of course is not part of the group nor of the name
> "pyribolite".  What's wrong with metamafite?  Pyroclasite is used by some
> European workers but to me implies orthoclase is possible too.
> eric
> 
> 
> Anthi, Jim and others,
> >        At this juncture, I'd like to put in a plug for the very useful
> term
> >"pyribolite", coined by Asger Berthelsen forty years ago to denote a
> >metamafite consisting of pyroxene, amphibole and plagioclase, which it
> would
> >be misleading to call amphibolite. Berthelsen (Meddelelser om Gronland,
> Bd.
> >123, Nr. 1, 1960) defined pyribolite to be a metamafite with an amph:px
> >ratio ranging from 66:33 to 33:66 but I personally take the liberty of
> >broadening that range to take in the bulk of high-grade mafic rocks that
> >cannot in good conscience be termed amphibolites. For metamafites with
> >50%
> >plagioclase, Berthelsen coined the term "pyriclasite".
> >        I am aware that J.B. Thompson in 1970 took over Johannsen's
> (1911)
> >collective noun for pyroxene  and amphibole, "pyribole", and proposed it
> for
> >minerals with combined pyroxene and mica-like structural units but
> there's
> >hardly much room for confusion: anyway Berthelsen preceded Thompson by 10
> >years.
> >        Cheers.
> >Tom Frisch
> >________________________
> >Thomas Frisch
> >Geological Survey of Canada
> >601 Booth Street
> >Ottawa, ON K1A 0E8
> >Canada
> >E-mail: [log in to unmask]
> >
> >
> >> Jim,
> >> There must be some misunderstanding. The rock I am talking about WAS an
> >> amphibolite which has undergone contact metamorphism due to a
> granodiorite
> >> intrusion. Contact metamorphism of this amphibolite resulted in the
> >> formation of the present cpx-opx-plag 'hornfelses, in which relics of
> the
> >> original amphibolite occur in form of patches.
> >> I hope this clarifies what I meant in my previous e-mail.
> >>
> >> cheers
> >> Anthi
> >> Dr Anthi Liati
> >> Institute of Isotope Geology and Mineral Resources
> >> Department of Earth Sciences
> >> ETH-Zentrum
> >> Sonneggstr. 5, 8092 Zürich
> >> Tel.  ++41 1 632 6607
> >>        ++41 1 632 3764 (secretary Mrs. Britt Meyer)
> >> Fax ++ 41 1 632 1827
> >>
> >>
> >>
> >>
> >> At 15:41 01.11.01 -0500, you wrote:
> >> >Anthi:
> >> >
> >> >        FWIW, with cpx+opx your assemblage is granulite or
> >> pyroxene-hornfels facies, not 'amphibolite'.  I agree totally that the
> >> rocks still may be 'amphibolite', and I share that use of the
> terminology
> >> for the rock.   Just thought this distinction might deserve mention.
> >> Everyone stay safe.
> >> >
> >> >
> >> >JIM ECKERT
> >> ><[log in to unmask]>
> >> >------------------------------------------------------------
> >> >James O. Eckert, Jr., Ph.D
> >> >Department of Geology and Geophysics, Yale University
> >> >------------------------------------------------------------
> >> >
> >>
> >> -----------------------------------------------------------------------
> >>
> 
> 
> Eric Essene
> Professor of Geology
> Department of Geological Sciences
> 2534 C.C. Little Bldg.
> 425 E. University Ave.
> University of Michigan
> Ann Arbor MI 48109-1063 USA
> fx: 734-763-4690
> ph: 734-764-8243
>