[meteorite-list] Met Bulletin Update - Sterley Approved (1950's Texas Pallasite)

[Galactic Stone & Ironworks]

Hi Bulletin Watchers,

Sterley was approved today -
http://www.lpi.usra.edu/meteor/metbull.php?code=56575

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Sterley        34.21°N, 101.39°W
Texas, USA
Found: 1950
Classification: Pallasite (Main group)

History: A single mass weighing 1724.8 grams, and displaying
regmaglypts and some remnant fusion crust, was found ~1950 by a farmer
while plowing. Several months later, the finder took the specimen to
Texas Tech University where it was classified by a mineralogist Mr.
Dennis as a " stony iron siderolite - variety pallasite".  Decades
later, after watching a television show on meteorites, the son of the
finder took the specimen to Dr. Laurence Garvie at the Center for
Meteorite Studies, ASU for further study. The pallasite was later
purchased by Ruben Garcia and Geoff Notkin.

Physical characteristics: Single, fragmental piece with a few patches
of remnant fusion crust. Greenish olivine crystals protruding from the
surface. Small area of farringtonite visible at the surface.
Weathering is minor and restricted primarily to small areas at the
edge of the stone.

Petrography: (L. Garvie, ASU). A 12 × 6 cm polished and etched slice
shows (areal %): swathing kamacite 39.8, plessite 20.0, olivine 36.2,
troilite 1.9, schreibersite 1.1, and farringtonite 0.9. Olivine grains
are typically well rounded and <1 cm, though some are angular.
Swathing kamacite, to 1-mm thick, well developed, some areas showing
prominent Neumann bands. Many of the plessite fields show
well-developed kamacite laths.

Geochemistry: (J. Wasson, UCLA; L. Garvie, ASU) Metal composition by
INAA (mean of two analyses) Ni 117 mg/g; Co 5.75 mg/g, Cu 316 μg/g, Ga
18.5 μg/g, As 26.5 μg/g, Ir 0.076 μg/g, and Au 2.727 μg/g.  EMPA of 13
separate olivine grains gave Fa17.5±0.1, FeO/MnO=54.6±4.7,
Cr2O3=0.03±0.01, n=19.  Based on the elemental composition and the
high olivine Fa content the meteorite appears to be unpaired with
other known pallasites.

Classification: Main-group pallasite.

Specimens: 141 g at ASU.

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Best regards,

MikeG


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