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Northwest Africa 13969
Basic information Name: Northwest Africa 13969
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13969
Observed fall: No
Year found: 2017
Country: (Northwest Africa)
Mass:help 102 g
Classification
  history:
Recommended:  C2-ung    [explanation]

This is 1 of 24 approved meteorites classified as C2-ung.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 2), and Ungrouped chondrites
Comments: Approved 17 Jul 2021
Writeuphelp
Writeup from MB 110:

Northwest Africa 13969 (NWA 13969)

(Northwest Africa)

Find: 2017

Classification: Carbonaceous chondrite (C2, ungrouped)

History: Several partially fusion-crusted stones weighing 102 g acquired by Ruben Garcia and Bob Cuchiara from Adam Aaronson at the 2017 Tucson Gem and Mineral show. 42 g was acquired by the Center for Meteorite Studies at ASU.

Physical characteristics: (L. Garvie, L. McCann, J. Miech, ASU) The largest fragment (27.3 g) is partly covered with ~0.3-1.0 mm in thick ropy fusion crust. The stones were noteworthy for being exceptionally light when picked up. The density of the 27.3 g stone is 1.56 g/cm3 (determined using glass bead methods with 100-µm sized beads). Microporosity estimated at 32% from BSE images. Total porosity estimated 46-51%, based on bulk grain densities of Murray and Murchison. The interior of the stones is dark gray-green with an abundance of small (<1 mm) chondrules and mineral fragments. Under the binocular microscope, the broken surfaces appear highly vesicular.

Petrography: (L. McCann, J. Miech, M. Hernandez, L. Garvie, ASU) A powder XRD pattern shows intense reflections for serpentine, tochilinite, olivine, magnetite/maghemite, calcite, and pentlandite. Low-magnification BSE images of the polished mount show abundant chondrules and chondrule fragments with fine-grained rims loosely packed together. The high porosity is evident as dark (BSE images) areas between the chondrules. Abundant porphyritic chondrules and rarer barred olivine chondrules, set within a serpentine-tochilinite dominated matrix. Chondrules have mean diameter of 268 µm (range=69-1277 µm, n=103). Chondrules primarily Type I (Mg # >90). Rare CAIs contain spinel, Al-rich pyroxene, hibonite, melilite, and perovskite and average ~135 µm (range 86-200 µm, n = 8). CAIs are mantled by thick fine-grained rims. Rare Mg-rich carbonates (average 126 µm in diameter, n = 9) are present. Rare metallic phases include a 10 µm kamacite grain within an olivine chondrule. Sparsely distributed 40-50 µm sulfides present in the form of pentlandite, pyrrhotite, and troilite. BSE images show euhedral fibrous tochilinite (to ~5 µm in length) within the pore spaces.

Geochemistry: Oxygen isotopes (K. Ziegler, UNM): 3 fragments analyzed by laser fluorination gave δ18O= -0.682, -3.272, -3.395; δ17O= -5.761, -7.509, -8.149; Δ17O=-5.400, -5.781, -6.357 (linearized, all per mil, TFL slope=0.528). Microprobe (L. McCann, J. Miech, M. Hernandez, A. Wittman, ASU):Two distinct populations of olivine, one with Fa2±1, n=58, Range: 0.5-6.4 and one with Fa34±11 n=19, Range: 17.2-57.7. Minor element phases in olivine CaO up to 1.8 wt%, Cr2O3 up to 0.6 wt%, NiO up to 0.1 wt%, Al2O3 up to 0.2 wt%. Pyroxene composition is En65-98, Fs1-34, Wo1-4 (n = 12).

Classification: C2 ungrouped. The stone has a type 2 petrographic type as evidenced by the serpentine dominated matrix . It contains abundant and relatively small chondrules and CAI. While mineralogically similar to CM chondrites, the oxygen isotopic compositions fall below CCAM at the lower end of the CV-CK field.

Specimens: 42 g at ASU.

Data from:
  MB110
  Table 0
  Line 0:
Place of purchase:Tucson
Date:2017
Mass (g):102
Pieces:23
Class:C2-ung
Weathering grade:low
Classifier:L. McCann, J. Miech, M. Hernandez, L. Garvie, K. Ziegler, A. Wittman
Type spec mass (g):42
Type spec location:ASU
Main mass:Ruben Garcia and Bob Cuchiara
Comments:ASU#2050; submitted by L. Garvie
Plots: O isotopes:  
Institutions
   and collections
ASU: Center for Meteorite Studies, Arizona State University, Tempe, Arizona 85287-1404, United States; Website (institutional address; updated 14 Jan 2012)
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
Aaronson: Sahara Overland Ltd., Harhora, Temara, 12000, Morocco (private address; updated 3 Jan 2010)
Catalogs:
References: Published in Meteoritical Bulletin, no. 110, in preparation (2021)
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Public domain photographs:
Laurence Garvie   
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 7937 approved meteorites from (Northwest Africa) (plus 1960 unapproved names)

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