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Northwest Africa 8709
Basic information Name: Northwest Africa 8709
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 8709
Observed fall: No
Year found: 2003
Country: (Northwest Africa)
Mass:help 79 g
Classification
  history:
Meteoritical Bulletin:  MB 104  (2015)  L3-melt breccia
Recommended:  L3-melt breccia    [explanation]

This is 1 of 3 approved meteorites classified as L3-melt breccia.   [show all]
Search for other: L chondrites, L chondrites (type 3), Melted chondrites, Ordinary chondrites, and Ordinary chondrites (type 3)
Comments: Approved 1 May 2015
Writeuphelp
Writeup from MB 104:

Northwest Africa 8709 (NWA 8709)

(Northwest Africa)

Purchased: 2003 Nov 23

Classification: Ordinary chondrite (L3, melt breccia)

History: An already cut individual of an NWA meteorite was purchased by Dick Pugh in November 2003 and May 2004 from a Portland, Oregon, vendor and donated to Cascadia.

Physical characteristics: An irregularly shaped specimen with a dark, bumpy exterior, which locally has remnant fusion crust and a reddish brown weathering patina. Cut faces are dark gray and show distinct chondrules.

Petrography: (M. Hutson and A. Ruzicka, Cascadia) Tightly packed and commonly ellipsoidal chondrules in thin section (mean diameters in two thin sections are 0.72±0.36 mm, N=30; and 1.0±0.4 mm, N=23) with long axes roughly aligned, are embedded in an igneous-textured matrix composed of fine-grained (<5-10 μm) olivine, low-Ca pyroxene, glass, Ca-pyroxene, sulfide, and metal (or weathered metal), with sulfide and metal sometimes forming larger globules (to 40 μm). Chondrules consist chiefly of olivine and low-Ca pyroxene containing many small sulfide or metal inclusions and veinlets, set in glass or fine grained mesostasis. Olivine grains in chondrules show undulose-mosaic extinction and planar fractures consistent with shock stage S4. 80-90% of opaque minerals are replaced by terrestrial weathering products. Weathering products and remaining metal and troilite constitute ~5 area % (visual estimate) of the coarser grains in thin sections. No clasts of different chondrite types are apparent.

Geochemistry: Olivine Fa15.6±2.9 (Fa2.1-20.8, N=99) and low-Ca pyroxene Fs 11.1±5.2Wo1.5±1.4 (Fs2.2-21.7, N=39) in chondrules. Oxygen isotopic composition (R. Greenwood, OU) of untreated bulk sample, δ17O 3.482, δ18O 5.033, Δ17O 0.865 (0.842 linearized), all permil.

Classification: Based on texture and mineral chemistry this stone is a type 3 chondritic melt breccia. Group affinity is likely L chondrite based on oxygen isotope composition (most consistent with L chondrite), chondrule size (consistent with L or LL chondrite), and overall amount of metal and sulfide and associated weathering products (consistent with L or LL chondrite). Mineral chemistry is not fully consistent with established chondrite groups and most closely resembles H chondrites.

Specimens: 70.8 g as well as polished thin section are on deposit at Cascadia, which holds the main mass. The original specimen is estimated to have been at least 79 g.

Data from:
  MB104
  Table 0
  Line 0:
Place of purchase:Hillsboro, Oregon
Date:P 2003 Nov 23
Mass (g):79
Pieces:1
Class:L3-melt breccia
Shock stage:S4
Weathering grade:W3
Fayalite (mol%):15.6±2.9
Ferrosilite (mol%):11.1±5.2
Wollastonite (mol%):1.5±1.4
Classifier:M. Hutson and A. Ruzicka, Cascadia
Type spec mass (g):70.8
Type spec location:Cascadia
Main mass:Cascadia
Comments:Lab number CML0109; submitted by Alex Ruzicka
Plots: O isotopes:  
Institutions
   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)
OU: Planetary and Space Sciences Department of Physical Sciences The Open University Walton Hall Milton Keynes MK7 6AA United Kingdom, United Kingdom (institutional address; updated 8 Dec 2011)
Catalogs:
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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Geography: 
Coordinates:Unknown.

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

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