[meteorite-list] Osceola Meteorite is Official!

From: Rob Matson <mojave_meteorites_at_meteoritecentral.com>
Date: Sat, 2 Apr 2016 13:02:24 -0700
Message-ID: <000c01d18d1a$92d9d2f0$b88d78d0$_at_cox.net>

Congratulations to Mike, Larry, Laura, Josh and Brendan for their aggressiveness in
getting to the fall location quickly and their persistence in the face of very
unfavorable searching conditions (SWAMP!) It is an impressive feat that anything
was found at all, even with the nice radar returns.

I have one correction: I'm pretty sure Larry was the second on the scene. Steve
Arnold drove all night from Arkansas to arrive (I believe) the morning after
the fall -- Monday, January 25. --Rob

-----Original Message-----
From: Meteorite-list [mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of Michael Gilmer via Meteorite-list
Sent: Saturday, April 02, 2016 11:00 AM
To: Meteorite List
Subject: [meteorite-list] Osceola Meteorite is Official!

Osceola meteorite is official, approved by NonCom and entered into the
Met Bull today - http://www.lpi.usra.edu/meteor/metbull.php?code=63109

Osceola 30?27.16?N, 82?27.25?W
Florida, USA
Confirmed fall: 2016 Jan 24
Classification: Ordinary chondrite (L6)

History: (Mike Hankey, Larry Atkins, Laura Atkins, Josh Adkins,
Brendan Fallon, Robert Matson, Marc Fries) On Sunday Morning 24
January at 10:27 EST (15:27 UTC) a large daytime fireball streaked
across the sky in northern Florida. Over 100 eyewitnesses reported the
event to the American Meteor Society (Event 2016-266), describing a
white sparkling head and plume of white smoke left behind. Fireball
researchers Marc Fries and Rob Matson, found the American Meteor
Society witness trajectory intersected with a group of radar returns
that appeared shortly after the fall. The radar returns were strong,
found at multiple altitudes and located on multiple stations: KJAX,
KVAX and KTHL. Larry Atkins was the first on the scene. Mike Hankey
arrived 5 days after the fall with Brendan Fallon and joined Larry and
Laura Atkins in the hunt. On the 6th day, Mike Hankey found the first
stone at 8.5 g on the eastern edge of the primary radar return. Within
2 hours Larry Atkins found the second stone (18.5 g) directly under
the radar. The next day, two more stones were found: a 5.5 g stone by
Laura Atkins and a 48.5 g stone by Mike Hankey. Six days later over 2
miles away from the first find, an 839 g mass was found by Josh Adkins
and Brendan Fallon. A week after that, Larry Atkins found the last
stone, weighing 75.5 g. In total 6 stones were found over a three week
hunting period for a total weight of 990.5 g.

Physical characteristics: Thin, well formed shiny fusion crust covers
the exterior of four of the stones, while two of them, the 43 g and
the 839 g are matte black. This is likely due to submersion in wet
sand and/or water prior to recovery. Some small rust spots are evident
on some of the stones as well. Small regmaglypts are present on the 43
g and the 839 g stones, and the remaining stones are irregularly
shaped with little to no orientation. Some chondrules are visible
through the crust. The interior of the meteorites are slightly
darkened due to shock. Shock veins are present, some of which are
black while others are filled with metal, appearing as long "strings"
up to 3 mm long. Though most of the chondrules have been altered and
are not well defined, some rare, large chondrules up to 0.8 mm are
present.

Petrography: Plagioclase grains are up to 100 ?m in size, consistent
with type 6. No maskelynite was found. There are numerous
chromite-plagioclase assemblages, consistent with moderately strong
shock. Chromite grains are fractured. Troilite is polycrystalline.
Metallic copper occurs as 2-?m-thick bands at the metal-troilite
interface in an opaque assemblage. The chondrules are recrystallized
and poorly defined. The only discernible chondrules are large ones,
800-1000 ?m across; these are BO and PO textural types.

Geochemistry: Olivine Fa23.7?0.3 (n=21), Orthopyroxene
Fs20.2?0.2Wo1.6?0.2 (n=14). Also present are small grains of diopside:
Fs7.4 Wo44.9 (n=1). Plagioclase has a mean composition of Ab71.7?1.6
Or8.8?2.5 (n=8); the low Na and high K values are a result of shock.

Specimens: 21.8 g at UCLA
______________________________________________

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Received on Sat 02 Apr 2016 04:02:24 PM PDT