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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 119 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 Photo added 20 Oct 2022
Mark Vornhusen Photo added 20 Oct 2022
Geography:

Algeria
Coordinates:Unknown.

Statistics:
     This is 1 of 1232 approved meteorites from Algeria (plus 29 unapproved names) (plus 4 impact craters)

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