[meteorite-list] Met Bulletin Update - Nininger's only cold find (Puente-Ladron)

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Thu, 24 Jul 2014 12:55:33 -0400
Message-ID: <CAKBPJW_kNyxvkGRQxXboiTwBg6oXBdNbmRAXdCaYyN59tYwzTw_at_mail.gmail.com>

Hi Bulletin Watchers,

There is one update to the bulletin. The full classification of
Puente-Ladron has been added. This was Harvey Nininger's only cold
find, which he spotted while taking a lunch break in the New Mexico
desert.

Link : http://www.lpi.usra.edu/meteor/metbull.php?code=18895

Best regards and Happy Huntings,

MikeG

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Description and full classification of Puente-Ladron
History: On May 17, 1944, Harvey H. Nininger stopped for lunch along a
stretch of highway in New Mexico and found an unusual-looking stone in
the desert that he thought might be a meteorite, which it was. The
full writeup of his discovery was published by Nininger (1944). This
was the only cold find of his career.
Physical characteristics: Single 7.673 g fusion-crusted roughly
pyramidal 1.5 ? 1.5 ? 2 cm stone. Fusion crust is dark gray and
relatively fresh, with minor weathering and few cracks. A few
recognizable chondrules (up to 1 mm) visible on sawn surface. Evenly
spaced, irregularly shaped metal grains up to 2 mm and troilite grains
up to 0.5 mm. Surface criss-crossed by thin black shock veins. Tan and
white matrix, with rust around the metal grains. Sparsely distributed
chromite grains to 200 ?m.
Petrography: In thin section, sample largely recrystallized with rare
recognizable chondrules. Chondrule-matrix boundary diffuse. A few
barred olivine and porphyritic olivine chondrules present. One 4 ? 3
mm achondritic clast composed of pyroxene, olivine, and plagioclase
with, grains up to 50 ?m. Some plagioclase grains up to 200 ?m. Opaque
shock veins with melt pockets present. Troilite along shock veins
commonly shows shock lamellae. Some troilite is polycrystalline. One
kamacite grain shows poorly developed Neumann bands. Some kamacite
grains up to 30 ?m contain abundant blebs of troilite. Two 10 ?m
grains of metallic copper found associated with troilite. Partially
recrystallized plagioclase. Olivine demonstrates weak undulatory
extinction indicative of S2. Sparse euhedral chromite to 50 ?m. Minor
oxidation around metal grains indicative of S1.
Geochemistry: (S. Glaser, K. Johnson, J. Long and L. Garvie, ASU):
EMPA, Olivine Fa25.0?0.3, FeO/MnO=51.4?5.8, n=11; low-Ca pyroxene
Fs21.0?0.1Wo1.8?0.3, FeO/MnO=29.5?1.0, n=6; high-Ca pyroxene
Fs7.0Wo46.6, FeO/MnO=19.2 and Fs7.8Wo45.6, FeO/MnO=21.4; plagioclase
Ab81.4An12.7Or5.8 and Ab79.6An14.1Or6.3
Classification: Ordinary chondrite, L6, W1, S2.
Specimens: 4.51 g stone, one polished thin section, and one polished
endpiece, ASU.
Submitted by L. Garvie, ASU.

Received on Thu 24 Jul 2014 12:55:33 PM PDT