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Northwest Africa 10658
Basic information Name: Northwest Africa 10658
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 10658
Observed fall: No
Year found: 2014
Country: (Northwest Africa)
Mass:help 319 g
Classification
  history:
Meteoritical Bulletin:  MB 105  (2016)  Eucrite-pmict
Recommended:  Eucrite-pmict    [explanation]

This is 1 of 344 approved meteorites classified as Eucrite-pmict.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 24 May 2016
Writeuphelp
Writeup from MB 105:

Northwest Africa 10658 (NWA 10658)

(Northwest Africa)

Purchased: 2014

Classification: HED achondrite (Eucrite, polymict)

History: A 319 g meteorite was purchased by Michael Farmer from a Moroccan dealer at the 2014 Tucson Gem and Mineral show.

Physical characteristics: Exterior is shiny, pitted and heavily sandblasted. Sawn surface shows a gray matrix hosting abundant rounded to sub-angular clasts up to 1 cm, though most are <2 mm across. Clasts show a range of colors from white to black.

Petrography: (A. Wittmann, L.A.J. Garvie, and C. Fudge ASU) In thin section, the stone exhibits a breccia texture of up to 4 mm angular to sub-rounded clasts. Some areas of the breccia matrix are filled with aphanitic melt containing troilite droplets. Most clasts are pyroxene-rich composed of blocky orthopyroxene crystals with >10 μm-thick lamellae of augite-diopside. The largest clast is a 4 mm plagioclase that poikilitically encloses up to 1 mm orthopyroxene oikocrysts that display 20 μm-thick lamellae of augite-diopside. The largest pyroxene clast is 3 mm long. Another clast component consists of 0.4 mm euhedral pigeonite and augite intergrown with equant, tabular plagioclase crystals riddled with tiny, crystallized melt inclusions. Ilmenite, SiO2, Cr-Fe-Ti spinel, and troilite are minor mineral components in these clasts. SiO2 occurs as <0.7 mm clasts and grains that are frequently intergrown with small opaque grains and pyroxene. Raman spectroscopy indicates the presence of coesite coexisting with silica glass in some grains; matrix and/or melt domains surrounding SiO2 grains show characteristic radial fractures. Accessory components are Cr-Fe-Ti spinel, ilmenite, troilite, and Fe-Ni metal. Most clasts are shocked showing mechanical twinning of pyroxene, plagioclase with planar deformation features, and partial to full transformation to maskelynite.

Geochemistry: (A. Wittmann, ASU) Electron microprobe analysis shows feldspar clasts with An88-93Or0.1-0.6, such with abundant crystallized melt inclusions are An82-87Or0.7-2.6; typical, blocky orthopyroxene crystals have Mg# 54-55, and are Fs29-48Wo2-4, with Fe/Mn 29-35; pigeonite associated with melt-inclusion-rich plagioclase has Mg# 37-38, and are Fs59Wo5.1-6.3, with Fe/Mn 31-35; augite-diopside has Mg# 69, and are Fs16-17Wo44-45, with Fe/Mn 22-24. EDS-analysis suggests Fe-metal contains up to 2 wt% Ni.

Classification: Achondrite (polymict eucrite), components are moderately shocked (S4).

Specimens: 43.2 g and one thin secion at ASU.

Data from:
  MB105
  Table 0
  Line 0:
Place of purchase:Tucson
Date:P 2014
Mass (g):319
Pieces:1
Class:Eucrite-pmict
Shock stage:moderate
Weathering grade:low
Ferrosilite (mol%):39.4±6.6; 59.0±0.4; 17.3±5.5
Wollastonite (mol%):2.2±0.7; 5.5±0.5; 44.2±1.2
Classifier:A. Wittmann, L. Garvie, C. Fudge, ASU
Type spec mass (g):43.2
Type spec location:ASU
Main mass:MFarmer
Comments:Submitted by L. Garvie
Institutions
   and collections
ASU: Center for Meteorite Studies, Arizona State University, Tempe, Arizona 85287-1404, United States; Website (institutional address; updated 14 Jan 2012)
MFarmer: Michael Farmer, P.O. Box 86059, Tucson, AZ 85754-6059, United States; Website (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 105, MAPS 52, 2411, September 2017. http://onlinelibrary.wiley.com/doi/10.1111/maps.12944/full
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Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 7101 approved meteorites from (Northwest Africa) (plus 2004 unapproved names)

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