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Northwest Africa 5517
Basic information Name: Northwest Africa 5517
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 5517
Observed fall: No
Year found: 2004
Country: (Northwest Africa)
Mass:help 369 g
Meteoritical Bulletin:  MB 104  (2015)  Achondrite-ung
Recommended:  Achondrite-ung    [explanation]

This is 1 of 138 approved meteorites classified as Achondrite-ung.   [show all]
Search for other: Achondrites, Ungrouped achondrites
Comments: Approved 3 Apr 2015
Writeup from MB 104:

Northwest Africa 5517 (NWA 5517)

Northwest Africa

Purchased: 2004

Classification: Ungrouped achondrite

History: Purchased from a dealer in Erfoud, Morocco, in 2004 by David DGregory.

Physical characteristics: The dark brown stone (369 g) is fully crusted with light to moderate desert ablation and minimal surface chemical weathering.

Petrography: (T. Bunch and J. Wittke. NAU) Fine-grained (<0.3 mm) with poikiloblastic texture, and composed of essentially equigranular olivine grains and clinopyroxene (Cr-diopside) oikocrysts enclosing small (< 0.03 mm) olivine chadacrysts. Orthopyroxene is absent. Mineral mode (in vol.%): olivine 56; clinopyroxene 42, metal+FeS 2. Most metal is stained by terrestrial weathering.

Geochemistry: Olivine grains and chadacrysts (Fa12.3-12.6, N = 4; Cr2O3 = 0.51-0.65 wt %; CaO = 0.28 wt %; FeO/MnO = 22), clinopyroxene (Fs6.0-6.2Wo39.0-39.3, N = 3; Cr2O3 = 1.35 wt %; Al2O3 = 1.25 wt %; FeO/MnO = 10), metal (Ni = 0.7 to 1.3 wt %). Oxygen isotopes (D. Rumble, CIW): an acid-washed and metal-free sample was analyzed in triplicate by laser fluorination and gave, respectively, δ17O = 2.570, 2.651, 3.117; δ18O = 6.618, 6.807, 7.681; Δ17O = -0.911, -0.929, -0.923 (all per mil).

Classification: Achondrite (ungrouped). Mineral and oxygen isotopic compositions indicate that this specimen has affinities to acapulcoites, but the poikiloblastic texture, complete lack of orthopyroxene and paucity of metal are anomalous features.

Specimens: 20.1 g including one polished thin section at UWB. The main mass is held by DGregory.

Data from:
  Table 0
  Line 0:
Place of purchase:Erfoud
Date:P 2004
Mass (g):369
Shock stage:low
Weathering grade:low
Fayalite (mol%):12.3-12.6
Ferrosilite (mol%):6.0-6.2
Wollastonite (mol%):39.0-39.3
Classifier:T. Bunch and J. Wittke, NAU
Type spec mass (g):20.1
Type spec location:UWB
Main mass:DGregory
Comments:Submitted by T. Bunch
Plots: O isotopes:  
   and collections
NAU: Geology, Bldg 12 Knoles Dr Northern Arizona University, Flagstaff, AZ 86011, United States; Website (institutional address; updated 12 Apr 2012)
UWB: University of Washington, Box 353010 Seattle, WA 98195, United States (institutional address; updated 27 Jul 2012)
CIW: Carnegie Insitution Washington, Geophysical Laboratory, 5251 Broad Branch Rd., NW, Washington DC 20015, United States (institutional address)
DGregory: David Gregory, 230 First Avenue, Suite 108, St. Thomas, Ontario N5R 4P5, Canada (private address)
References: Published in Meteoritical Bulletin, no. 104, MAPS 52, 2284, Octover 2017, http://onlinelibrary.wiley.com/doi/10.1111/maps.12930/full
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     This is 1 of 9368 approved meteorites from (Northwest Africa) (plus 1875 unapproved names)

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