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Northwest Africa 13758
Basic information Name: Northwest Africa 13758
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13758
Observed fall: No
Year found: 2017
Country: Algeria
Mass:help 100 kg
Classification
  history:
Recommended:  R3    [explanation]

This is 1 of 61 approved meteorites classified as R3.   [show all]
Search for other: Rumuruti chondrites, Rumuruti chondrites (type 3)
Comments: Approved 8 Apr 2021
Revised 23 Apr 2022: added note
Writeuphelp
Writeup from MB 110:

Northwest Africa 13758 (NWA 13758)

Adrar, Algeria

Purchased: 2017

Classification: Rumuruti chondrite (R3)

History: A large group of identically appearing stones, found together, was purchased by a Saharan dealer from a nomad in Algeria and was subsequently acquired by Mark Lyon and Dustin Dickens. The original find was reportedly in the Tanezrouft Plateau, with the nearest town being Reggane, Algeria.

Physical characteristics: Approximately 500 pieces ranging in mass from <1 kg to >5 kg, with a total known weight of approximately 100 kg. Dark brown sandblasted exterior. Saw cut reveals a breccia with fragments up to ~2 cm set in a fine-grained matrix. Abundant distinct chondrules are visible throughout. Two main lithologic domains exist within this meteorite, one has a gray, unstained matrix, and the second has a brownish-orange-stained matrix.

Petrography: (C. Agee, UNM) Chondrite with mean apparent chondrule size 350±240 µm (n=21) set in abundant matrix (~35 vol%). Electron microprobe analyses were performed separately on the two main lithologic domains. Domain "A" has compositionally unequilibrated olivine and pyroxene both in chondrules as well as single mineral fragments in the matrix. Very small grains of albitic plagioclase are present. Chromite, pentlandite, and troilite are ubiquitous. No metal or oxidized iron was detected. Domain "B" has compositionally unequilibrated olivine and pyroxene both in chondrules as well as single mineral fragments in the matrix. Domain "B" appears to have slightly more chondrules than domain "A". Very small grains of albitic plagioclase were present. Ti-rich chromite, pentlandite, and Ni-bearing troilite are ubiquitous. No metal or oxidized iron was detected.

Geochemistry: (C. Agee, UNM) Domain "A": olivine Fa36.6±8.4, CV=23%, Fe/Mn=83±15, n=12; low-Ca pyroxene Fs21.4±6.8Wo0.9±0.5, Fe/Mn=39±19, n=4; augite Fs8.8±0.7Wo46.0±0.2, Fe/Mn=43±4, n=2; plagioclase An8.8±0.6Ab86.5±0.2Or4.7±0.7, n=3. Domain "B": olivine Fa38.7±5.8, CV=15%, Fe/Mn=87±10, n=12; low-Ca pyroxene Fs10.0±7.7Wo2.0±1.8, Fe/Mn=15±7, n=4; augite Fs11.4±0.9Wo44.8±1.3, Fe/Mn=51±11, n=2; plagioclase An9.2±0.9Ab85.9±1.6Or4.9±0.8, n=3.

Classification: Rumuruti chondrite (R3). Domain "A" is approximately R3.7 and domain "B" is approximately R3.9, based on olivine coefficient of variation (CV) after Bischoff (2000).

Specimens: 1127.72 g complete stone, and a 57.69 g full slice from a different complete stone, are on deposit at UNM. Mark Lyon holds the main mass including a total of 14 pieces weighing 19.84 kg, Dustin Dickens holds ~60 kg of medium to small stones.


Writeup from MB 111:
Added notes for NWA 13758

(C. Agee, UNM) The total weight of the R chondrite described here, under the name NWA 13758, was originally stated to be 100 kg. It is possible that other R chondrites from northwest Africa with official names, listed as found or purchased since 2017, could be stones taken from this same 100 kg. According to Dustin Dickens (pers. comm. to Carl Agee, 2021), the total mass of paired stones is likely to be about 200 kg. Assuming accurate pairings of NWA R chondrites could be established, their published masses should not be added together to determine the total recovered mass from the NWA 13758 strewnfield, as the same stones would likely be counted more than once.
Bibliography:
  • Bischoff, A. (2000) Mineralogical characterization of primitive, type-3 lithologies in Rumuruti chondrites. Meteorit. Planet. Sci. 35 699-706 (link)
Data from:
  MB110
  Table 0
  Line 0:
State/Prov/County:Adrar
Origin or pseudonym:Tanezrouft
Place of purchase:Algeria
Date:P 2017
Mass (g):100000
Pieces:500
Class:R3
Shock stage:S2
Weathering grade:W1
Fayalite (mol%):36.6±8.4, 38.7±5.8
Ferrosilite (mol%):21.4±6.8, 10.0±7.7
Wollastonite (mol%):0.9±0.5, 2.0±1.8
Classifier:C. Agee, UNM
Type spec mass (g):1185.41
Type spec location:UNM
Main mass:Mark Lyon
Comments:Submitted by C. Agee
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. 110, in preparation (2021)
Published in Meteoritical Bulletin, no. 111, in preparation (2022)
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)
Domjan Svilkovic   
Ryan Upchurch      
Geography:

Algeria
Coordinates:Unknown.

Statistics:
     This is 1 of 178 approved meteorites from Adrar, Algeria (plus 1 unapproved name)
     This is 1 of 1213 approved meteorites from Algeria (plus 29 unapproved names) (plus 4 impact craters)

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