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Northwest Africa 10519
Basic information Name: Northwest Africa 10519
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 10519
Observed fall: No
Year found: 2015
Country: Mauritania
Mass:help 18.2 kg
Classification
  history:
Meteoritical Bulletin:  MB 105  (2016)  Enst achon-ung
Recommended:  Enst achon-ung    [explanation]

This is 1 of 5 approved meteorites classified as Enst achon-ung.   [show all]
Search for other: Achondrites, Enstatite achondrites, Enstatite-rich meteorites, and Ungrouped achondrites
Comments: Approved 3 Feb 2016
Writeuphelp
Writeup from MB 105:

Northwest Africa 10519 (NWA 10519)

Mauritania

Purchased: 2015 Sept

Classification: Enstatite achondrite (ungrouped)

History: Purchased by Michael Farmer from a meteorite dealer at the Denver Gem and Mineral Show, September 2015. The stone was reportedly found in Mauritania.

Physical characteristics: Single, deeply regmaglypted stone weighing 18.197 kg, with remnant fusion crust. Fusion crust on some edges of the stone is worn away, exposing metal. A 21 × 14 cm slab displays a brecciated texture dominated by sub-angular to rounded dark-green to tan metal-silicate clasts, separated by an anastomosing network of metal veins. Recognizable clasts up to 10 cm. Clasts range from blocky, dark-greenish and metal poor (<2 area %) to sub-rounded with ~20 area % metal. The dark blocky clasts commonly have a lighter colored greenish rim (to 1 mm thick). Overall the weathering grade is low, W1, although a few areas near the edge of the sample show W2. Shock stage is low, troilite is single crystal and metal lacks Neumann bands.

Petrography: (D. Schrader and L. Garvie, ASU) Electron microprobe analysis shows the silicates are enstatite, diopside, and albitic plagioclase, with minor silica. No olivine was observed. Metal is commonly associated with troilite, alabandite, daubrelite, and minor graphite and schreibersite. Areas of metal, to 2 cm across, show well-developed Widmanstätten pattern, with variable band-width with an average of 0.5 mm. Individual kamacite lamellae typically short, stubby and swollen, with rounded ends, and locally forms 120° triple grain boundaries with adjacent lamellae. Metal shows well-developed dark etching and comb plessite. Metal grain boundaries are decorated with submicron precipitates. Alabandite is present as grains up to 1 mm wide around large metal segregations and grains within troilite. Daubrelite is present as lamellae within troilite. Metal in clasts typically shows grains with holly-leaf to amoeboid outlines.

Geochemistry: (D. Schrader, ASU) Enstatite Fs0.6±0.3Wo1.2±0.4, Fe/Mn=5±2, n=13; diopside Fs0.7±0.2Wo46.6±1.0, Fe/Mn=6±5, n=7; plagioclase An21.6±0.2Ab76.4±0.3Or1.9±0.1, n=3; and silica. Opaque minerals observed include kamacite (wt.%; Fe 92.6±0.4, Ni 6.6±0.2, Co 0.4±0.0, Si <0.01, P 0.1±0.0; n = 16), taenite (wt.%; Fe 71.2±7.0, Ni 27.7±6.4, Co 0.1±0.0, Si <0.01), P <0.02; n = 2), troilite (wt.%; Fe 62.7±0.1, S 36.6±0.2, Ti 0.17±0.03, Cr 0.37±0.07; n = 4), alabandite, daubréelite, and schreibersite.

Classification: Ungrouped enstatite achondrite. The meteorite is texturally and chemically similar to the EL6 chondrite Blithfield, compared to data in Rubin (1984). However, this meteorite is distinguished from enstatite meteorites by the lack of Si in metal (below 0.01 wt.%) and the low Ti content of troilite (0.17±0.03 wt.%).

Specimens: A sample of 562 g and a polished mount is at ASU. Main mass of 5.5 kg with Boudreaux. Remainder with MFarmer.

Bibliography:
  • Rubin A.E. (1984) The Blithfield meteorite and the origin of sulfide-rich, metal-poor clasts and inclusions in brecciated enstatite chondrites. Earth Planet. Sci. Letts. 67, 273-283. (link)
Data from:
  MB105
  Table 0
  Line 0:
Place of purchase:Denver, CO
Date:P 2015 Sept
Mass (g):18197
Pieces:1
Class:Enst achon-ung
Shock stage:low
Weathering grade:W1
Ferrosilite (mol%):0.6±0.3
Wollastonite (mol%):1.2±0.4
Classifier:D. Schrader, L. Garvie, ASU
Type spec mass (g):562
Type spec location:ASU
Main mass:MFarmer and Terry Boudreaux
Finder:anonymous
Comments:Submitted by D. Schrader
Institutions
   and collections
ASU: Center for Meteorite Studies, Arizona State University, Tempe, Arizona 85287-1404, United States; Website (institutional address; updated 14 Jan 2012)
Boudreaux: Terry Boudreaux, Illinois, United States (private address)
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:

Mauritania
Coordinates:Unknown.

Statistics:
     This is 1 of 127 approved meteorites from Mauritania (plus 1 unapproved name) (plus 2 impact craters)

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