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Northwest Africa 13531
Basic information Name: Northwest Africa 13531
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13531
Observed fall: No
Year found: 2017
Country: (Northwest Africa)
Mass:help 22.9 g
Recommended:  Lunar (feldsp. breccia)    [explanation]

This is 1 of 220 approved meteorites classified as Lunar (feldsp. breccia).   [show all]
Search for other: Lunar meteorites
Comments: Approved 19 Nov 2020
Writeup from MB 109:

Northwest Africa 13531 (NWA 13531)

(Northwest Africa)

Purchased: 2017 Mar

Classification: Lunar meteorite (feldspathic breccia)

History: Writeup history: History: Roger Kilchenmann obtained this meteorite in March 2017 from Noreddine Azelmat of Morocco as part of an online trade for a lot of NWA meteorites.

Physical characteristics: Exterior covered with weathering rind and remnant fusion crust. Cut face reveals predominantly light toned interior with darker veins and pockets, with small (<=1 mm) white clasts.

Petrography: (M. Hutson, A. Ruzicka, Cascadia): Two lithologies are visible in thin section; both are breccias consisting of feldspathic clasts set in a finer-grained matrix dominated by pigeonite and plagioclase. The two lithologies differ in size of feldspathic clasts (up to 2 mm across in lithology 1, up to 0.7 mm across in lithology 2) and matrix texture (blocky plagioclase grains up to 0.1-0.2 mm across in lithology 1, lath-like plagioclase grains <0.1 mm long in lithology 2). An ovoid shaped patch of clast-laden brownish glass about 1 mm in length and thin glassy melt veins occur along the boundary between the two lithologies. Mineral phases present include plagioclase feldspar, pigeonite, augite, olivine, Cl-containing phosphate, ilmenite, Ti-rich spinel, chromite, troilite, and rare tiny (<= 10 μm across) FeNi metal.

Geochemistry: Mineral compositions and geochemistry: (M. Hutson, A. Ruzicka, Cascadia; K. Ziegler, UNM): Oxygen isotopes on acid treated samples in per mil, relative to V-SMOW linearized values): δ17O’ = 3.083±0.031, δ18O’ = 5.933±.052, Δ17O’ = -0.050±.005 (N=3). Plagioclase compositions of clasts are variable, but the range of compositions in the two lithologies overlap. Lithology 1 clasts: An87-96Or0.7-1.5 (N=18, 2 clasts); Lithology 2 clasts: An89-95Or0.7-1.1 (N=21, 3 clasts). Matrix plagioclase for the two lithologies is also similar. Lithology 1 matrix: An91.3±2.3Or0.9±0.6 (N=23); Lithology 2 matrix: An92.7±2.2Or0.9±0.9 (N=27). Matrix pigeonite (Wo5-20) and olivine grains are more magnesian in lithology 1 than in lithology 2. Lithology 1 matrix pigeonite: Fs29.9±3.1, Mg# = 67.9±3.2 (N=17); Lithology 2 matrix pigeonite: Fs31.7±1.9, Mg# = 64.2±1.1 (N=13); Lithology 1 matrix olivine: Fa39.8±2.2, Mg# = 60.2±2.1 (N=11); Lithology 2 matrix olivine: Fa43.4±0.9, Mg# = 56.5±0.9 (N=15).

Classification: Lunar feldspathic breccia based on texture and mineralogy.

Specimens: Cascadia holds 7.9 g in pieces, as well as a polished thin section and butt.

Data from:
  Table 0
  Line 0:
Place of purchase:Internet
Date:P 2017 Mar
Mass (g):22.9
Class:Lunar (feldsp. breccia)
Classifier:M. Hutson and A. Ruzicka, Cascadia
Type spec mass (g):7.9
Type spec location:Cascadia
Main mass:Roger Kilchenmann
Comments:Lab number CML 0929; submitted by Alex Ruzicka
Plots: O isotopes:  
   and collections
Cascadia: Cascadia Meteorite Laboratory, Portland State University, Department of Geology, Room 17 Cramer Hall, 1721 SW Broadway, Portland, OR 97201, United States; Website (institutional address; updated 28 Oct 2011)
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
References: Published in Meteoritical Bulletin, no. 109, in preparation (2020)
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     This is 1 of 7655 approved meteorites from (Northwest Africa) (plus 1972 unapproved names)

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