[meteorite-list] "White Mountains" June 2016 Arizona Fall is now official - Dishchii'bikoh

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Mon, 29 May 2017 10:32:14 -0400
Message-ID: <CAKBPJW9_ifdu+B05TiGbgf2n5vLZHf7tsn2CL6G-+=HUgZBunA_at_mail.gmail.com>


33?53?0.48"N, 110?38?8.20"W

Arizona, USA
Confirmed fall: 2 Jun 2016
Classification: Ordinary chondrite (LL7)

History: (D. Dunlap, M. Fries, R. Garcia, L. Garvie, M. Hankey, R.
Matson, P. Mane, M. Miller, R. Ward) At 3:56:34 MST (10:56:34 UTC) on
2 June 2016, a bright fireball was widely observed throughout the
southwestern US. The fireball was recorded in imagery from the NOAA
NEXRAD weather radar network, on the KFSX radar in Flagstaff, Arizona.
Radar reflections consistent with falling meteorite material were
first recorded at 10:57:12 UTC at an altitude of 9.7 km above sea
level (ASL). Two additional radar sweeps recorded the event, at
11:01:14 UTC (5.1 km ASL) and 11:02:30 UTC (5.1 km ASL). The mass of
meteorites for these detections was estimated at 3.7 kg, 2.15 g, and
0.54 g respectively, using M. Fries? dark-flight model J?rmungundr
(v.42) and wind velocity data from a radiosonde launched from
Flagstaff at 00:00 UTC. The fireball was also recorded on US
Department of Defense orbital sensors, leading to a total radiated
energy of 17.2 ? 1010 J, with energy equivalent to 0.49 kiloton of
TNT. The air-blast shockwave was recorded on the earthquake seismic
network from the Payson-Strawberry station. Analysis of the Doppler
radar data showed stones likely on the ground on the southwestern
corner of the White Mountain Apache tribal (WMAT) lands. With the help
of Jacob Moore (Assistant Vice-president of Tribal Relations, ASU),
permission was granted by Ronnie Lupe, the WMAT Tribal Chairman, to
enter the tribal lands and search for and collect meteorites. Laurence
Garvie, Daniel Dunlap, and Prajkta Mane of ASU, and private meteorite
hunters Robert Ward, Mike Miller, and Ruben Garcia searched for
meteorites starting 22 June 2016. Robert Ward found the first stone,
0.93 g, at 33?53?19.7 N and 110?37?55.0? W. A total of 15
fusion-crusted stones weighing from 0.9 to 28.6 g, for a total of
79.46 g, were found on 22 and 23 June, 2016. The stones were found
along a 1.7 km transect, with a 10.16 g stone found at 33?53?0.48"N
and 110?38?8.20"W near the center of the finds, though this location
is likely at the small end of a large strewnfield that extends to the

Physical characteristics: (L. Garvie, D. Dunlap, P. Mane, ASU; R.
Ward, M. Miller, R. Garcia). Fifteen fusion-crusted stones for a total
mass of 79.46 g. Fusion crust is dominantly shiny black, though on two
stones it is brown, matte, and powdery. Five of the stones broke upon
impact. Interiors are whitish gray, with uneven distribution of darker
clasts to 5 mm, and troilite to 3 mm. Stones are dominantly soft with
a sugary texture.

Petrography: (L. Garvie, ASU) Pieces of four stones were mounted in
epoxy and polished. Sections show a breccia of clasts dominated by
granoblastic textures in a cataclastic matrix. Granoblastic areas:
areas with this texture occur as rounded clasts with a sharp boundary
to the cataclastic material. No easily recognizable chondrules were
visible, though one 200-?m-sized grain may be a remnant BO chondrule,
and two rounded 500 ?m-sized areas with finer-grained pyroxene than
enclosing material may represent former PO chondrules. Silicates
typically <400 ?m. Feldspars coarse grained, commonly >50 ?m, some
grains to 300 ?m. Troilite and taenite <400 ?m across, rounded to
subhedral. Troilite ~2 areal%, taenite ~1 areal% and trace kamacite.
Troilite is single crystal and lacks shock lamellae. Native copper is
sparse, to 30 ?m. Accessory chromite to 200 ?m. Cataclastic areas:
Angular silicates to 200 ?m. Troilite grains with feathery margins,
though still single crystal and lacking shock lamellae. One section is
traversed by several shock veins, with the sulfide dominantly
fine-grained anastomosing network. Sulfide-rich clasts, to 2.5 mm,
with FeS finely dispersed as small grains or as anastomosing network.

Geochemistry: (L. Garvie ASU, P. Mane, UAz) Olivine, low-Ca pyroxene,
and plagioclase dominate the sections. Microprobe results from the
cataclastic and granoblastic regions are the same. Olivine Fa31.0?0.3,
FeO/MnO=59.6?3.4, n=14; low Ca-pyroxene Fs25.0?0.3Wo1.8?0.3,
FeO/MnO=35.6?2.0, n=9; high Ca-pyx Fs11.2Wo43.1, FeO/MnO=46.6, n=1;
plagioclase Ab85.8?1.6An10.9?0.5, n=10; taenite - Ni 50.0?3.1 wt%, Co
1.9?0.2 wt%, Cu 0.18?0.06, n=10; kamacite - Ni 3.7?0.5 wt%, Co
11.8?0.7 wt%, n=10; chromite - Cr/(Cr+Al) = 0.85?0.01, Fe/(Fe+Al) =
0.79?0.03, n=10; and, phosphates dominated by apatites with F 1.1?0.3
wt% and Cl 4.4?0.3 wt%, n=7.

Classification: Ordinary chondrite, LL7, S3, W0.

Met Bull link - https://www.lpi.usra.edu/meteor/metbull.php?code=65525

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Received on Mon 29 May 2017 10:32:14 AM PDT

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