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Northwest Africa 8276
Basic information Name: Northwest Africa 8276
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 8276
Observed fall: No
Year found: 2013
Country: (Northwest Africa)
Mass:help 789 g
Classification
  history:
Meteoritical Bulletin:  MB 103  (2014)  L3.00
Recommended:  L3.00    [explanation]

This is 1 of 2 approved meteorites classified as L3.00.   [show all]
Search for other: L chondrites, L chondrites (type 3), Ordinary chondrites, and Ordinary chondrites (type 3)
Comments: Approved 6 Mar 2014
Writeuphelp
Writeup from MB 103:

Northwest Africa 8276 (NWA 8276)

(Northwest Africa)

Purchased: 2013

Classification: Ordinary chondrite (L3.00)

History: Adam Bates identified this meteorite from images he received as a possible pairing to NWA 7731, even though they came from a different Moroccan meteorite dealer. Both pieces were then purchased within a few weeks of each other in October 2013. The meteorite dealer claimed both pieces originated in Mauritania.

Physical characteristics: A single stone, broken into two pieces (394 and 395 g) that fit together, >90% black fusion crust with polygonal cracks, light desert weathering, saw-cut reveals many densely packed chondrules of variable size.

Petrography: (C. Agee, UNM) Microprobe examination of a polished mount shows numerous unequilibrated chondrules, apparent mean diameter 496±296 μm (n=122), many with porphyritic, igneous-zoned olivines and pyroxenes, most with glass or mesostasis. Abundant fine-grained matrix throughout.

Geochemistry: (C. Agee, N. Muttik, H. Miley, UNM) All chondrule olivine Fa12.2±9.3, range Fa0.7-26.3, n=67; ferroan olivine Fa17.8±5.9, Fe/Mn=47±11, Cr2O3=0.42±0.10 wt%, range Cr2O3=0.29-0.66 wt%, n=44; low-Ca pyroxene Fs13.0±8.3Wo1.9±2.7, Fe/Mn=26±14, n=41. Augite and aluminous diopside present. Mesostasis or glass (n=25) in 10 ferroan porphyritic chondrules Na2O=6.27±3.20 wt%, K2O=0.51±0.40 wt%, Na/Al=1.14, K/Al=0.95 (mean values, CI normalized). Fine-grained matrix S=1.7±1.6 wt%, n=17. Oxygen isotopes (Karen Ziegler, UNM) Oxygen isotope values of 3 acid-washed aliquots of bulk sample, 1.1, 1.3, 1.4 mg, gave δ17O = 3.589, 2.734, 2.839, δ18O = 5.511, 4.643, 4.201, Δ17O = 0.679, 0.282, 0.621 (linearized, all permil).

Classification: Ordinary chondrite (L3.00), type 3.00 based on ferroan olivine mean Cr2O3 content and sigma from Grossman and Brearley (2005) and by the presence of S-rich matrix. Comparison of Cr2O3 in ferroan olivines done using the same microprobe and conditions at UNM gave: NWA 7731 (L3.00) Cr2O3=0.43±0.11 wt%, n=98; Semarkona (LL3.00) Cr2O3=0.41±0.09 wt%, n=45. Oxygen isotopes appear to be relatively heterogeneous and fall within the same range of δ17O and δ18O as NWA 7731 (Ziegler et al., 2014). Apparent mean chondrule size similar to NWA 7731 (Agee et al., 2013). Weathering grade (W1). Possibly paired with NWA 7731.

Specimens: 20.1 g including a probe mount on deposit at UNM, Adam Bates, Mendy Ouzillou, and Darryl Pitt hold the main mass.

Bibliography:
  • Agee C.B., Burkemper L.K., Muttik N. and Spilde M.N. (2013) New primitive ordinary chondrite: Northwest Africa 7731. 76th Annual Meeting of the Meteoritical Society, abstract #5130. (link)
  • Ziegler K., Agee C.B., and Connolly H.C. (2014) The oxygen isotope systematics of the L3.00 ordinary chondrite NWA 7731, and a comparison to LL3.00 Semarkona. 45th Lunar and Planetary Science Conference, abstract #2468. (link)
Data from:
  MB103
  Table 0
  Line 0:
Place of purchase:Morocco
Date:P 2013
Mass (g):789
Pieces:2
Class:L3.00
Weathering grade:W1
Fayalite (mol%):12.2±9.3
Ferrosilite (mol%):13.0±8.3
Wollastonite (mol%):1.9±2.7
Classifier:C. Agee, UNM
Type spec mass (g):20.1
Type spec location:UNM
Main mass:Adam Bates, Mendy Ouzillou, and Darryl Pitt
Comments:Submitted by C. Agee, UNM
Plots: O isotopes:  
Institutions
   and collections
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
Catalogs:
References: Published in Meteoritical Bulletin, no. 103, MAPS 52, 1014, May 2017, http://onlinelibrary.wiley.com/doi/10.1111/maps.12888/full
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)
Solar Anamnesis   
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 6900 approved meteorites from (Northwest Africa) (plus 2035 unapproved names)

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