[meteorite-list] Thin Sections of Carancas Meteorite

[Rob Matson]

Hi Sterling and List,

> The INGEMMET report at:
> http://www.ingemmet.gob.pe/paginas/pl01_quienes_somos.aspx?opcion=320
> contains photos of four of the meteorites and
> three thin section photos, two of them polarized.
> Text in English. People who understand thin
> sections (not me) are invited to comment in
> reply, please.

This can't be the first time this report has been referenced on
the Meteorite List, can it?!  I've had this report for a week and a
half, and indeed it was the "smoking gun" I was waiting for that
converted me from a skeptic to a believer (and will eventually cost
me a trio of beers in an international bet with a prominent MPML
member ;-)

As I pointed out on MPML, the exterior images were far from convincing
(e.g. no fusion crust), but the plane- and crossed-polarized thin
sections left little doubt (despite the nominal quality of the thin
sections).  My post on MPML from Sept. 27th:

"I have uploaded to the files area a copy of the INGEMMET initial report
on the ~possible~ Carancas Meteorite fall (07_09_21_Carancas_meteorite.pdf).
In it on page 3, you can finally see some images of small samples of the
purported stony meteorite. Better yet, on page 4 there are petrologic
microscope images of a thin section under plane- and crossed-polarized
light.

"Based only on the images of the exteriors, I would consider the
specimens very unlikely to be chondritic. But there ~are~ some chondrite-
like features in the thin sections (though I wouldn't call them
unambiguously chondrules). The rims are indistinct, there are no shock
veins visible, and the interference colors don't seem quite right. I'll
forward the images to a few experts to get their opinions, but if this
is a chondrite, it would seem to be a metamorphised, highly brecciated
one."

--Rob