[meteorite-list] Official Announcement NWA 6077 is Paired with NWA 5400

From: John higgins <geohiggins_at_meteoritecentral.com>
Date: Tue, 5 Oct 2010 06:26:05 -0700 (PDT)
Message-ID: <741690.55990.qm_at_web63207.mail.re1.yahoo.com>

Official Announcement
?
NWA 6077 IS PAIRED WITH NWA 5400
?
North West Africa 6077?Description:
An olivine-rich assemblage with cumulate (or possibly metamorphic) texture
exhibiting triple junction grain boundaries. Olivine (Fa30.2-30.7),
orthopyroxene (Fs24.1-24.5Wo2.1-2.0), clinopyroxene (Fs9.4-10.0Wo44.0-43.5),
altered kamacite, chromite, chlorapatite, Ni-bearing troilite and/or pyrrhotite.
No plagioclase was found. Analysis conducted at the Carnegie Institution of
Washington show that the oxygen isotopic composition of this specimen plots on
the Terrestrial Fractionation Line. In conjunction with the mineral compositions
and texture, this establishes that NWA 6077 is paired with NWA 5400.
?
The averages of the two Oxygen Isotope Results are:
d17O = 2.780, d18O = 5.358, D17O = -0.019 (all in per mil)
?
This brachinite was recovered out of Morocco in 2008?as one whole stone and
purchased by John Higgins. It was submitted for classification to Dr. Tony
Irving and was given the provisional classification number of NWA 6077. This
meteorite has a modest TKW of less than 1000g after the type specimen was
removed.
?
Personal?Notes: Although I suspected that the two were possibly?paired due to
similarities in?visual observations?and classification compositions, I felt it
was important to wait for secondary Oxygen Isotope results to come in which have
recently confirmed the results beyond a reasonable doubt. There was also another
important factor besides Oxygen Isotope testing that?had to be taken into
account. Orthopyroxene which is present in NWA 5400?was missed the first time
around in NWA 6077?because it looks identical to clinopyroxene in back-scattered
electron images.?However?further in-depth microprobe?studies of the thin section
have confirmed?the presence of?orthopyroxene, and?are now noted in the updated
description. I feel that making a self pairing based upon my own
visual?observations, is not only unethical, inappropriate, and akin to pirating,
but would only feed the controversies regarding this meteorite without the
scientific testing data to back up such speculation, such action would be
premature, immoral?and unfair to Greg Hupe and NWA 5400 after all the time and
effort he put into the study of what has become one of the most important
meteorite finds in history.
?
Have a Great Day!
John Higgins
IMCA#9822


      
Received on Tue 05 Oct 2010 09:26:05 AM PDT