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Northwest Africa 14749
Basic information Name: Northwest Africa 14749
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 14749
Observed fall: No
Year found: 2000
Country: Morocco
Mass:help 352 g
Classification
  history:
Recommended:  L4    [explanation]

This is 1 of 1999 approved meteorites (plus 4 unapproved names) classified as L4.   [show all]
Search for other: L chondrites, L chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 6 Aug 2022
Writeuphelp
Writeup from MB 111:

Northwest Africa 14749 (NWA 14749)

Morocco

Purchased: 2000

Classification: Ordinary chondrite (L4)

History: Sample was purchased at the Tucson mineral show in 2000 from J. Aaronson, who acquired it from Morocco. Sample is catalogued at the Royal Ontario Museum as M60220.

Physical characteristics: Fist-sized individual with mature desert polish on fusion crust and broken surfaces. Some chondrules of mm size are visible through weathered fusion crust and in broken surfaces. Physical properties: Magnetic susceptibilty of the 20.69 g type specimen is log χ (× 10-9 m3/kg) = 3.82.

Petrography: Cut faces show intact, well-dispersed chondrules set in a mottled, dun-brown weathered matrix. Metal is rare, but patches of Fe oxides and vugs are present. A dark, porous fine-grained 1.5 cm subangular clast is visible in broken surface and adjacent cut face. In polished thin section, well-delineated chondrules and chondrule fragments of types POP, PO, PP, RP and CC are set in a finely recrystallized matrix. Chondrules and clast components have dark fine grained rims of matrix material. The 1.5 cm subangular clast is represented in the thin section, along with two smaller, 2 mm subangular clasts. The main clast contains subhedral to euhedral olivine and pyroxene grains, some with skeletal texture, ranging from 300 µm down to fine scale in a dark matrix. No chondrules are present and metal is lacking, but vugs up to 800 µm are present. Smaller clasts in the thin section similarly bear individual olivine and pyroxene grains in a dark matrix; one clast has large, euhedral olivine grains and the other clast consists mostly of finer-grained olivine and pyroxene in a dark matrix. All three clasts appear to be igneous. Olivine and pyroxene grains in chondrules and in the clasts show sharp to undulatory extinction. Metal occurs as isolated 200 μm subrounded grains in the matrix. Sulfide is more abundant and occurs as isolated grains and in some rims of chondrules. Pockets and chondrule-rimming veins of Fe oxides are visible throughout the host chondrite, often associated with sulfides as an apparent alteration product. In BSE images, olivine grains in the clast as well as all chondrule types typically contain sub-mm curvilinear trails of chromite grains, a likely indicator of high shock and annealing.

Geochemistry: EPMA: olivine Fa25.46±0.42 (n=60); Ca-poor pyroxene Fs21.05±0.65Wo2.12±1.92 (n=48); Ca-rich pyroxene Fs13.59±4.68Wo27.72±15.15 (n=34). Subangular clast: olivine Fa25.20±0.36 (n=24); Ca-poor pyroxene Fs20.76±0.74Wo2.72±2.33 (n=22); Ca-rich pyroxene Fs14.46±5.00Wo23.35±15.39 (n=11). Host chondrite: olivine Fa25.63±0.38 (n=36); Ca-poor pyroxene Fs21.29±0.44Wo1.62±1.34 (n=26); Ca-rich pyroxene Fs13.18±4.58Wo29.82±14.92 (n=23). Powder XRD analysis indicates olivine to have a structural unit cell consistent with Fa25.2.

Classification: Ordinary chondrite L4 (S2) W3. Powder XRD olivine of Fa25.2 and EPMA olivine and pyroxene compositions consistent with L chondrite designation and compositional standard deviations suggest L4, consistent with petrographic observations of well-delineated chondrules, chondrule rims and a finely recrystallized matrix. Clast olivine and pyroxenes are compositionally indistinguishable from those of the host L chondrite, suggesting that the clast may be an L melt rock fragment. Two other small igneous clasts in the section may represent different samples of the melt rock. Low observed metal content and magnetic susceptibility is inconsistent with L chondrite, but likely a result of the observed significant weathering of metal to Fe oxides and presence of porosity.

Specimens: Type specimen ROM; main mass DGregory

Data from:
  MB111
  Table 0
  Line 0:
Place of purchase:Tucson, USA
Date:P 2000
Mass (g):352.3
Pieces:1
Class:L4
Shock stage:S2
Weathering grade:W2
Fayalite (mol%):25.46±0.42
Ferrosilite (mol%):21.05±0.65, 13.59±4.68
Wollastonite (mol%):2.12±1.92, 27.72±15.15
Magnetic suscept.:3.82
Classifier:P. McCausland (ROM, UWO), K. Hewson (ROM), V Di Cecco (ROM)
Type spec mass (g):20.69
Type spec location:ROM
Main mass:DGregory
Comments:Submitted by V. Di Cecco, ROM
Institutions
   and collections
ROM: Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada (institutional address; updated 18 Oct 2011)
UWO: University of Western Ontario, Department of Earth Sciences, BGS 1026, 1151 Richmond St. N, London, Ontario, Canada N6A 5B7, Canada (institutional address; updated 18 Jul 2015)
Aaronson: Sahara Overland Ltd., Harhora, Temara, 12000, Morocco (private address; updated 3 Jan 2010)
DGregory: David Gregory, 230 First Avenue, Suite 108, St. Thomas, Ontario N5R 4P5, Canada (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 111, in preparation (2022)
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Geography:

Morocco
Coordinates:Unknown.

Statistics:
     This is 1 of 1902 approved meteorites from Morocco (plus 27 unapproved names) (plus 1 impact crater)

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