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

From: Thunder Stone <stanleygregr_at_meteoritecentral.com>
Date: Tue, 5 Oct 2010 08:31:36 -0700
Message-ID: <SNT117-W166D87ACAA70EEAB20910BD26D0_at_phx.gbl>

List:

This is amazing; is it possible that all of these (NWA 5400, 5363, 6292 and 6077) are from the same strewn field?

Greg S.

----------------------------------------
> Date: Tue, 5 Oct 2010 06:26:05 -0700
> From: geohiggins at yahoo.com
> To: meteorite-list at meteoritecentral.com
> Subject: [meteorite-list] Official Announcement NWA 6077 is Paired with NWA 5400
>
> 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
>
>
>
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Received on Tue 05 Oct 2010 11:31:36 AM PDT