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Northwest Africa 16755
Basic information Name: Northwest Africa 16755
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 16755
Observed fall: No
Year found: 2023
Country: Algeria
Mass:help 3.97 kg
Classification
  history:
Recommended:  R4    [explanation]

This is 1 of 69 approved meteorites classified as R4.   [show all]
Search for other: Rumuruti chondrites, Rumuruti chondrites (type 4-7)
Comments: Approved 10 Jun 2024
Writeuphelp
Writeup from MB 113:

Northwest Africa 16755 (NWA 16755)

Algeria

Purchased: 2023

Classification: Rumuruti chondrite (R4)

History: This meteorite was reportedly found in Algeria and subsequently purchased by Adam Aithiba in 2023.

Physical characteristics: Exterior surface is light brown, sandblasted to reveal numerous chondrules. Saw-cut surface shows many small to medium sized dark-colored chondrules set in a light brown-green matrix.

Petrography: (C. Agee, UNM) Microprobe analysis and reflected light microscopy reveal an unbrecciated meteorite with densely packed porphyritic chondrules. Opaques include chromite, Fe-sulfide, and Fe-Ni sulfide. No metal or magnetite were detected.

Geochemistry: (C. Agee, UNM) Olivine Fa38.4±0.3, Fe/Mn=87±2, n=6; augite Fs12.8±1.4Wo44.5±0.7, Fe/Mn=41±11, n=5; low-Ca pyroxene Fs24.6±5.8Wo1.3±1.5, Fe/Mn=37±6, n=2; plagioclase An14.5±10.7Ab81.9±9.8Or3.5±1.0, n=5. Oxygen isotopes (K. Ziegler, UNM): 3 acid-washed fragments analyzed by laser fluorination gave δ18O= 4.550, 4.476, 4.379; δ17O= 5.427, 4.607, 5.104; Δ17O= 1.684, 2.043, 1.685 (linearized, all per mil, TFL slope=0.528).

Classification: Rumuruti chondrite (R4). R is based on oxygen isotopes, olivine Fe/Mn, presence of augite, nickel bearing olivine, and nickel-bearing sulfide. Type 4 based on standard deviation of average Fa-content and presence of many porphyritic chondrules with fine-grained plagioclase + mesostasis.

Specimens: 37.7 g on deposit at UNM, Adam Aithiba holds the main mass.

Data from:
  MB113
  Table 0
  Line 0:
Place of purchase:Algeria
Date:P 2023
Mass (g):3970
Pieces:1
Class:R4
Shock stage:low
Weathering grade:moderate
Fayalite (mol%):38.4±0.3
Ferrosilite (mol%):24.6±5.8, 12.8±1.4
Wollastonite (mol%):1.3±1.5, 44.5±0.7
Classifier:C. Agee, UNM
Type spec mass (g):37.7
Type spec location:UNM
Main mass:Adam Aithiba
Comments:Fieldname AD-3975; submitted by C. Agee
Plots: O isotopes:  
Institutions
   and collections
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
Catalogs:
References: Published in Meteoritical Bulletin, no. 113, in preparation (2024)
Find references in NASA ADS:
Find references in Google Scholar:
Geography:

Algeria
Coordinates:Unknown.

Statistics:
     This is 1 of 1368 approved meteorites from Algeria (plus 31 unapproved names) (plus 4 impact craters)

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