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Northwest Africa 6557
Basic information Name: Northwest Africa 6557
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 6557
Observed fall: No
Year found: 2010
Country: Morocco
Mass:help 68 g
Classification
  history:
Meteoritical Bulletin:  MB 99  (2011)  Acapulcoite
Recommended:  Acapulcoite    [explanation]

This is 1 of 74 approved meteorites classified as Acapulcoite.   [show all]
Search for other: Acapulcoite-lodranite family, Acapulcoites, and Primitive achondrites
Comments: Approved 6 May 2011
Writeuphelp
Writeup from MB 99:

Northwest Africa 6557 (NWA 6557)

Morocco

Found: 2009

Classification: Primitive achondrite (Acapulcoite)

History: A fresh 68 g stone with fusion crust was purchased by Darryl Pitt from a dealer in Erfoud, Morocco.

Petrography: Equigranular recrystallized texture with triple junctions. Mean grain size is 0.24 mm. Mineral modes (vol%): orthopyroxene, 38; olivine, 35; plagioclase, 12; Ca-pyroxene, 7; opaques, 8. Shock level and weathering grade are low.

Geochemistry: Orthopyroxene, Fs12.5 (FeO/MnO = 12); olivine, Fa13.9 (FeO/MnO = 16); plagioclase, An6.8Or5.5; chromite, cr# = 87; Ca-pyroxene, Fs8.1Wo36.8; kamacite (Ni = 6.2 wt%). Oxygen isotopes (D. Rumble, CIW): replicate analyses of acid-washed material by laser fluorination gave, respectively δ17O = 0.64, 0.55; δ18O = 3.05, 2.79; Δ17O = -0.962, -0.913 (all per mil).

Classification: Achondrite (acapulcoite).

Specimens: A total of 14 g is on deposit at NAU. Mr. D. Pitt holds the main mass.

Data from:
  MB99
  Table 0
  Line 0:
Place of purchase:Erfoud
Date:2009
Mass (g):68
Pieces:1
Class:Acapulcoite
Shock stage:low
Weathering grade:low
Fayalite (mol%):13.5
Ferrosilite (mol%):12.5
Wollastonite (mol%):2.4
Classifier:Bunch/Wittke
Type spec mass (g):14
Type spec location:NAU
Main mass:D. Pitt
Comments:Submitted by Bunch
Plots: O isotopes:  
Institutions
   and collections
NAU: Geology, Bldg 12 Knoles Dr Northern Arizona University, Flagstaff, AZ 86011, United States; Website (institutional address; updated 12 Apr 2012)
CIW: Carnegie Insitution Washington, Geophysical Laboratory, 5251 Broad Branch Rd., NW, Washington DC 20015, United States (institutional address)
Catalogs:
References: Published in Meteoritical Bulletin, No. 99, April 2012, MAPS 47, E1-E52 (2012) [published online only]
Find references in NASA ADS:
Find references in Google Scholar:
Geography:

Morocco
Coordinates:Unknown.

Statistics:
     This is 1 of 1374 approved meteorites from Morocco (plus 16 unapproved names) (plus 1 impact crater)

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