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Northwest Africa 4657
Basic information Name: Northwest Africa 4657
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 4657
Observed fall: No
Year found: 2006
Country: Algeria
Mass:help 417 g
Classification
  history:
Meteoritical Bulletin:  MB 93  (2008)  CK4
Recommended:  CK4    [explanation]

This is 1 of 112 approved meteorites classified as CK4.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (equilibrated), CK chondrites, CK chondrites (type 4-6), and CV-CK clan chondrites
Comments: Approved 1 Jan 2008
Revised 4 Aug 2008: final writeup
Writeuphelp
Writeup from MB 93:

Northwest Africa 4657

Algeria

Find: 2006

Carbonaceous chondrite (CK4)

History and Physical characteristics: Purchased by B. Reed from a dealer in Erfoud, Morocco, in 2006. The single stone is a light greenish gray, 417 g stone that is partially crusted on ~70% of the surface and moderately to heavily desert-etched on the remaining surface.

Petrography: (J. Wittke and T. Bunch, NAU) Contains ~18 vol% well-defined chondrules, some of which are up to 2 mm in diameter. The matrix is partially recrystallized with tiny plagioclase grains intermingled with amorphous plagioclase aggregates. Chondrule glass is mostly devitrified.

Mineral compositions and Geochemistry: Olivine shows a narrow spread in FeO, although at lower values (Fa27.3-28.2) compared with typical CK chondrites; FeO/MnO = 95-123. Orthopyroxene (Fs23.8Wo2.2), magnetite (Cr2O3 = 3.79 wt%; Al2O3 = 1.56 wt%; NiO = 0.90 wt%), plagioclase (An27.9-49).

Classification: Carbonaceous chondrite (CK4); moderate weathering and minimal shock.

Type specimens: A 23 g sample is on deposit at NAU. Reed holds the main mass.

Submitted by: T. Bunch, NAU.

Data from:
  MB93
  Table 2
  Line 88:
Place of purchase:Erfoud, Morocco
Date:2006
Mass (g):417
Pieces:1
Class:CK4
Type spec mass (g):23
Institutions
   and collections		 NAU: Geology, Bldg 12 Knoles Dr Northern Arizona University, Flagstaff, AZ 86011, United States; Website (institutional address; updated 12 Apr 2012)
Reed: Blaine Reed, P.O. Box 1141, Delta, CO 81416, United States; Website (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 93, MAPS 43, 571-632 (2008)
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Photos:
CreditPhotos
Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)
Argus Rocks   
Mark Vornhusen   
Geography:

Algeria
Coordinates:Unknown.

Statistics:
     This is 1 of 1133 approved meteorites from Algeria (plus 27 unapproved names) (plus 4 impact craters)

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