[meteorite-list] Met Bulletin Update - Indian Butte Fall, Vestans, Type-3's

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Wed, 29 May 2013 12:46:23 -0400
Message-ID: <CAKBPJW8VGXm7K7Akfx1fr4VsuUam-3ePVnjTQ+6arGp01hWZnw_at_mail.gmail.com>

Hi Bulletin Watchers,

There are several new approvals. Most of them are meteorites from
various deserts (NWA, Chile, etc). One is the Indian Butte Arizona
fall of 1998. There are also several Vestans and type-3 finds newly
approved.

Link - http://www.lpi.usra.edu/meteor/metbull.php?sea=&sfor=names&ants=&falls=&valids=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&categ=All&mblist=All&rect=&phot=&snew=1&pnt=Normal%20table&dr=&page=0

>From the Indian Butte write-up :

Indian Butte 32?51.860?N, 112?2.920?W
Pinal County, Arizona, USA
Fell: 7 June 1998
Classification: Ordinary chondrite (H5)

History: The following lines of evidence support a connection between
the Indian Butte stones and the "Casa Grande" fireball of 7 June 1998:
1) The discovery location is consistent with the triangulated endpoint
based on fireball reports; 2) The location is directly under a Doppler
radar return; 3) The stones are fresh (weathering grade W0 to 1).
Doppler radar was first used in 2009 to locate the Ash Creek meteorite
fall. The Indian Butte radar signal was recently identified during a
search of historic falls. Some stones have been marketed under the
synonym "Stanfield". A 128 gram stone was discovered by Robert
Reisener, Sonny Clary, and Fredric Stephan while investigating a
doppler radar signal corresponding to the "Casa Grande" fireball of 7
June 1998. At least 30 other stones were subsequently found. The
Doppler signature was identified by Marc Fries and Robert Matson using
fireball witness reports collected by Robert Ward. The location of
discovery is near the area searched by David Kring and others
immediately after the fireball.

Physical characteristics: At least 30 fusion-crusted stones have been
recovered, with a total mass of 1721 grams. The fusion crust is fresh,
although many stones display slight oxidation on the bottom where they
lay on the desert surface. The interior metal is free of limonite
rinds, indicative of weathering grade W0.

Petrography: (A.Rubin, UCLA) The chondrite is moderately
recrystallized. Polysynthetically twinned low-Ca pyroxene is absent. A
few small grains of diopside have grown large enough to be analyzed
with the electron microprobe. Plagioclase has also grown fairly
coarse; grains up to 25 ?m across are present.

Geochemistry: Olivine, Fa17.9?0.3; pyroxene, Fs16.0?0.2Wo1.5?0.2.
Mineralogical equilibrium has occurred.

Classification: Ordinary chondrite (H5). Shock stage = S1 and
weathering grade = W0.

Specimens: Most stones are privately held; 22.2 grams have been
deposited at UCLA.

Best regards and happy huntings,

MikeG

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Received on Wed 29 May 2013 12:46:23 PM PDT