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Northwest Africa 8707
Basic information Name: Northwest Africa 8707
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 8707
Observed fall: No
Year found: 2012
Country: Morocco
Mass:help 64.5 g
Classification
  history:
Meteoritical Bulletin:  MB 104  (2015)  L-melt rock
Recommended:  L-melt rock    [explanation]

This is 1 of 35 approved meteorites classified as L-melt rock.   [show all]
Search for other: L chondrites, L chondrites (type 4-7), Melted chondrites, Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 30 Mar 2015
Writeuphelp
Writeup from MB 104:

Northwest Africa 8707 (NWA 8707)

Morocco

Purchased: Feb 2012

Classification: Ordinary chondrite (L, melt rock)

History: Purchased by T. Ono in Tucson in Feb. 2012

Physical characteristics: A single stone of 64.5 g, ~70% covered with fresh black fusion crust. Broken surfaces reveal a light gray interior with abundant shock melt veins.

Petrography: (T. Mikouchi, UTok). Faintly brecciated (cm-to-mm scale) igneous rock mainly composed of olivine, pyroxene and feldspathic glass with variable grain sizes ranging from 0.05 mm to 1 mm. Most pyroxenes are larger than 0.5 mm and poikilitically enclose olivine chadacrysts. Olivine is rounded in shape and its size ranges 0.05-0.5 mm. Feldspathic glass is interstitial to olivine and pyroxene. There are some areas where feldspar is birefringent under petrographic microscope. Both olivine and pyroxene exhibit undulatory extinction and shock veins (~ 0.2 mm wide) cut through the section, suggesting severe shock metamorphism. In shock melt veins some olivine grains are transformed to ringwoodite. Although the shock metamorphism is extensive, the original igneous texture is well preserved. Mineral abundances are 53 olivine, 18 feldspathic glass, 15 low-Ca pyroxene, 4 high-Ca pyroxene, 4 Fe-Ni metal, 4 troilite, 1 chromite and 1 apatite (in vol%).

Geochemistry: (T. Mikouchi, UTok). All phases show fairly homogeneous compositions. Olivine is Fa23.6±0.9 and its FeO/MnO ratio is 35-60 (N=256). CaO and Cr2O3 are <0.05 wt%, respectively. Low-Ca pyroxene is Fs19.7±0.9Wo3.3±1.0 with 0.3-0.4wt% Al2O3 and 0.3-0.6 wt% Cr2O3 (N=89). Its FeO/MnO ratio (wt%) is 25-40. High-Ca pyroxene is Fs9.0±1.0Wo42.0±1.9 with 0.5-1.0 wt% Al2O3, 0.3-0.4 wt% TiO2, 0.7-1.0 wt% Na2O and 1.1-1.7 wt% Cr2O3 (N=34). Feldspathic glass is Si-rich (71±2.2 wt% SiO2, 23.2±1.1 wt% Al2O3) and does not show a stoichiometric composition of feldspar (N=144). CaO, Na2O and K2O are 1.5-3.5, 1.0-1.5 and 0.4-0.9 wt%, respectively. There is no compositional difference between optically isotropic and anisotropic areas. Chromite contains 58-59 wt% Cr2O3, 28-29 wt% FeO, 4.5 wt% Al2O3, 3 wt% MgO and 2 wt% TiO2 (N=18). Kamacite has 6 wt% Ni and 0.9 wt% Co. Taenite contains 18 wt% Ni and 0.7 wt% Co.

Classification: L melt rock (strongly shocked). Texturally similar to acapulcoite/lodranite, but mineral compositions are in the range of equilibrated L chondrites.

Specimens: 15.4 g at UTok. Main mass with T. Ono

Data from:
  MB104
  Table 0
  Line 0:
Place of purchase:Tucson, USA
Date:P Feb 2012
Mass (g):64.5
Pieces:1
Class:L-melt rock
Shock stage:high
Weathering grade:low
Fayalite (mol%):23.6±0.9
Ferrosilite (mol%):19.7±0.9; 9.0±1.0
Wollastonite (mol%):3.3±1.0; 42.0±1.9
Classifier:T. Mikouchi, UTok
Type spec mass (g):15.4 g
Type spec location:UTok
Main mass:T. Ono
Comments:Submitted by T. Mikouchi
Institutions
   and collections
UTok: Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan (institutional address; updated 5 Nov 2011)
Catalogs:
References: Published in Meteoritical Bulletin, no. 104, MAPS 52, 2284, Octover 2017, http://onlinelibrary.wiley.com/doi/10.1111/maps.12930/full
Find references in NASA ADS:
Find references in Google Scholar:
Geography:

Morocco
Coordinates:Unknown.

Statistics:
     This is 1 of 1390 approved meteorites from Morocco (plus 16 unapproved names) (plus 1 impact crater)

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