[meteorite-list] International Brachinite Day - Hug your Brachinite!

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Thu, 30 Jul 2009 16:37:38 -0400
Message-ID: <e51421550907301337g4fa60301wce938f8e3c7c072f_at_mail.gmail.com>

Hi List!

To celebrate the 462nd annual International Brachinite Day, I thought
I might share a few photos of my latest acquisition - NWA 5471.

Many of you on the List have seen this meteorite before, but for those
who have not, here is some background information on it...

I received this 1.74 gram slice from Martin Altmann at Chladni's
Heirs. Thanks again Martin! :)

Brachinite is very difficult to photograph because it's almost
entirely composed of olivine - which is tricky to get proper lighting.

Some research suggests that brachinites originate from the
olivine-rich asteroid 289 Nenetta. At first, it was thought that
brachinites were Martian members of the Chassignite family - because
Chassigny contains a similar amount of olivine. But oxygen isotopic
age studies revealed that olivine is far too old to be Martian and it
shows some affinities to the eucrite group.

Brachinites are rather boring to look at under typical lighting, but
it reveals it's true beauty under cross-polarized light - click on the
following link to see :

http://www4.nau.edu/meteorite/Meteorite/Brachinite.html

Martin's description of this brachinite is apt -

"Brachinites rank among the most enigmatic meteorites, they are
primitive dunitic rocks, though their isotopes and petrology are so
heterogeneous, that so far no satisfying theory about their origins
and formation could have been established. Brachinites are exceedingly
rare, the combined weights of all finds in history do not exceed
10kgs, making this class five times rarer than lunar meteorites. NWA
5471 is weakly shocked and moderately weathered. "

This specimen is part of my new collecting strategy - nothing under 1
gram unless it's Lunar or Martian. (or similarly cost-prohibitive).
In the past, I would have been happy with a 100mg specimen. This
particular small slice is 1.746 grams.

Photo links :

http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/brachinite/brach-1.jpg

http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/brachinite/brach-2.jpg

http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/brachinite/brach-3.jpg

Best regards and clear skies,

MikeG

-- 
.........................................................
Michael Gilmer (Florida, USA)
Member of the Meteoritical Society.
Website - http://www.galactic-stone.com
Personal Site - http://www.glassthrower.com
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..........................................................

Received on Thu 30 Jul 2009 04:37:38 PM PDT