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Northwest Africa 13919
Basic information Name: Northwest Africa 13919
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13919
Observed fall: No
Year found: 2019
Country: Algeria
Mass:help 74.1 g
Classification
  history:
Recommended:  LL3    [explanation]

This is 1 of 369 approved meteorites classified as LL3.   [show all]
Search for other: LL chondrites, LL chondrites (type 3), Ordinary chondrites, and Ordinary chondrites (type 3)
Comments: Approved 29 May 2021
Writeuphelp
Writeup from MB 110:

Northwest Africa 13919 (NWA 13919)

Algeria

Find: 2019

Classification: Ordinary chondrite (LL3)

History: The meteorite was found by nomads in Algeria in 2019. Zs. Kereszty purchased the stone from a Moroccan dealer from the city of Guelmim in October 2020.

Physical characteristics: (D. Rezes and Zs. Kereszty, CSFK) Originally an individual egg-shaped (3 × 4 × 4.5 cm) brown stone (74.1 g) without fusion crust. The stone has shiny, dark desert varnish on most of its sides. On the surface of the stone many different colored (green, bluish gray, black) chondrules bulge out from the brown groundmass. Largest objects on the surface are a chondrule with 0.8 mm diameter and a black clast with 0.9 mm length. Cut surface reveals scarce shiny metal and sulfide phases. Inside the stone there are two distinct lithologies with intact, well-defined chondrules (radial, barred, granular, porphyritic and bleached textures). One of the two lithologies shows densely packed chondrules with rare matrix material. This part contains a black clast. The other one shows loosely packed chondrules with more abundant matrix. The boundary of the two parts is not sharp.

Petrography: (D. Rezes, CSFK) Chondrite composed of well-defined chondrules with average diameter of 840 µm, N=94 (Lithology 1) and 804 µm, N=32 (Lithology 2). Largest chondrule of the thin section has 4582 µm length and 3144 µm width. Minor mineral phases are FeNi, troilite and Fe,Ni-sulfides. Lithology 1 shows densely packed chondrules with rare opaque matrix material, while Lithology 2 shows loosely packed chondrules with more abundant matrix that contains broken chondrules and crystals. Devitrified mesostasis is present in several chondrules, however chondrule glass is still observable in both lithologies.

Geochemistry: (D. Rezes, CSFK) Lithology 1 (densely packed chondrules, rare matrix material): Chondrule ferroan olivine Fa26.2±8.4 (range Fa10.3-41.9), CaO(wt%)=0.12±0.06 (range 0.03-0.31), Cr2O3(wt%)=0.06±0.06 (range 0.00-0.31), Fe/Mn=63.1±16.1, N=61; enstatite Fs2.8±0.1Wo0.6±0.1 (range Fs2.7-2.8Wo0.4-0.8), Fe/Mn=17.2±5.2, N=4; augite crystallites Fs18.9±5.1Wo38.4±3.5 (range Fs14.0-23.4Wo34.9-41.7), Fe/Mn=18.8±10.5, N=4; Glass in type-II chondrules SiO2=65.25±2.25, TiO2=0.49±0.13, Al2O3=12.02±2.01, Cr2O3=0.20±0.25, FeO=5.54±1.89, MnO=0.10±0.04, NiO=0.01±0.01, MgO=6.14±2.70, CaO=1.95±0.91, Na2O=7.82±1.28, P2O5=0.38±0.30, SO3=0.09±0.26, N=8 (all in wt%); Matrix S(wt%)=0.29±0.10, N=4. Lithology 2 (loosely packed chondrules, more abundant matrix): Chondrule ferroan olivine Fa27.0±9.9 (range Fa6.7-40.7), CaO(wt%)=0.16±0.09 (range 0.01-0.43), Cr2O3(wt%)=0.07±0.06 (range 0.00-0.27), Fe/Mn=69.4±18.4, N=46; enstatite Fs15.5±7.2Wo1.8±1.6 (range Fs7.6-23.2Wo0.2-4.2), Fe/Mn=23.2±2.2, N=12; pigeonite Fs22.6±0.5Wo8.5±1.8 (range Fs22.2-23.3Wo6.9-10.9), Fe/Mn=25.3±1.1, N=4; Glass in type-II chondrules SiO2=66.74±4.71, TiO2=0.54±0.10, Al2O3=14.02±1.38, Cr2O3=0.18±0.22, FeO=3.26±0.65, MnO=0.08±0.05, NiO=0.01±0.02, MgO=2.45±1.24, CaO=3.19±2.49, Na2O=8.05±0.96, P2O5=1.23±0.51, SO3=0.26±0.42, N=7 (all in wt%); Matrix S(wt%)=0.34±0.14, N=4.

Classification: Brecciated unequilibrated ordinary chondrite (LL3), estimated subtypes of the lithologies are LL3.3 and LL3.4. LL based on average chondrule diameter and low metal content. Subtype is based on mean Cr2O3-content and sigma of ferroan olivine from Grossman and Brearley (2005). The Cr2O3 values and standard deviation of ferroan chondrule olivines are in the field of UOCs with petrologic type >3.2. The presence of glass in chondrules indicate petrologic type <3.5. Shock stage S2, weathering grade W2.

Specimens: 15 g on deposit at CSFK, ZKereszty holds the main mass.

Bibliography:
  • Grossman J.N. and Brearley A.J. (2005) The onset of metamorphism in ordinary and carbonaceous chondrites. Meteorit. Planet. Sci. 40, 87-122. (link)
Data from:
  MB110
  Table 0
  Line 0:
Place of purchase:Guelmim
Date:2019
Mass (g):74.1
Pieces:1
Class:LL3
Shock stage:S2
Weathering grade:W2
Fayalite (mol%):26.2±8.4 (N=61); 27.0±9.9 (N=46)
Ferrosilite (mol%):2.8±0.1 (N=4); 18.9±5.1 (N=4); 15.5±7.2 (N=12);
Wollastonite (mol%):0.6±0.1 (N=4); 38.4±3.5 (N=4); 1.8±1.6 (N=12);
Classifier:D. Rezes, CSFK
Type spec mass (g):15
Type spec location:CSFK
Main mass:ZKereszty
Comments:Work name: ZK-22; submitted by Daniel Rezes
Institutions
   and collections
ZKereszty: Gyor, Lahner 1. 9024 , Hungary (private address; updated 8 Sep 2014)
CSFK: Research Center for Astronomy and Earth Sciences, H-1121 Budapest, Konkoly Thege Miklós út 15-17.l Hungary, Hungary (institutional address; updated 7 Apr 2015)
Catalogs:
References: Published in Meteoritical Bulletin, no. 110, in preparation (2021)
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Public domain photographs:
Daniel Rezes         
Geography:

Algeria
Coordinates:Unknown.

Statistics:
     This is 1 of 1118 approved meteorites from Algeria (plus 27 unapproved names) (plus 4 impact craters)

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