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Northwest Africa 10518
Basic information Name: Northwest Africa 10518
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 10518
Observed fall: No
Year found: 2004
Country: (Northwest Africa)
Mass:help 111 g
Meteoritical Bulletin:  MB 105  (2016)  L3-7
Recommended:  L3-7    [explanation]

This is 1 of 3 approved meteorites classified as L3-7.   [show all]
Search for other: L chondrites, L chondrites (type 3), Ordinary chondrites, and Ordinary chondrites (type 3)
Comments: Approved 27 Feb 2016
Writeup from MB 105:

Northwest Africa 10518 (NWA 10518)

(Northwest Africa)

Purchased: 2004 Feb

Classification: Ordinary chondrite (L3-7)

History: A single stone was obtained by Edwin Thompson from a Moroccan trader in Tucson, Arizona at the February 2004 Tucson Gem and Mineral Show. A portion (24 g) was donated and Patrick Thompson sold the main mass (85.6 g) to Cascadia.

Physical characteristics: Fusion crust, weathered patina, and dust partly cover exterior. Cut faces reveal light colored, partly reddish stained clasts and chondritic texture (chondrules, fragments, metal) with a grey matrix. One prominent large clast is ~2 × 1 cm across; a grey inclusion is also visible.

Petrography: (A. Ruzicka and K. Farley, Cascadia) In thin section, a breccia composed of an intimate mixture of mineral and chondrule fragments with diverse (type 3-6) characteristics and some larger clasts; areas between chondrules and clasts composed largely of smaller clasts. BSE imaging shows that most of the rock ("host") is composed of type 4-6 lithologies, with equilibrated olivine, and plagioclase commonly ~35-100 μm across, intermixed with well-defined chondrules and clasts with magnesian silicates. Prominent large clast contains granoblastic silicates, metal, relict chondrules, and feldspar which is especially coarse (length 75-326 μm, average 143±59 μm, N=35). Gray inclusion is ~8 mm long in thin section and composed chiefly of fine-grained zoned olivine set in glass.

Geochemistry: (K. Farley and A. Ruzicka) Host dominated by equilibrated olivine (median Fa24.8, N=72) and low-Ca pyroxene (median Fs21.0, N=53) but containing more varied olivine (Fa0-39.5) and low-Ca pyroxene compositions (Fs1.8-26.5). Overall average host including mixture of equilibrated and more varied compositions is olivine (Fa21.3±7.8, Fe/Mn = 42.9±18.6 at., N = 72), low-Ca pyroxene (Fs18.6±5.3Wo1.6±1.4En79.8±5.9, Fe/Mn = 23.5±9.3 at., N = 53), high-Ca pyroxene (Fs9.6±2.4Wo43.5±2.5En46.9±1.6, Fe/Mn = 11.1±7.3 at., N= 29), feldspar (Ab82.8±3.4An11.7±2.5Or5.4±2.1, N = 34). Prominent large clast has olivine (Fa25.7±0.7, Fe/Mn = 53.9±20.5 at., N = 10), low-Ca pyroxene (Fs22.0±0.9Wo1.9±0.5En76.0±1.0, Fe/Mn = 23.4±10.0 at., N = 7), high-Ca pyroxene (Fs9.5±2.2Wo43.8±2.3En46.7±1.5 at., N = 8), feldspar (Ab82.2±1.3An11.2±1.0Or6.6±1.0 at., N = 10).

Classification: L3-7 finely intermixed genomict breccia. Type 5-6 lithology implied by abundant equilibrated olivine and pyroxene and common coarse feldspar grain sizes; type 3 lithology implied by presence of magnesian olivine in chondrules and clasts; large prominent clast with unusually coarse feldspar can be described as type 7. Gray inclusion resembles shock melt observed in other ordinary chondrites.

Specimens: Cascadia holds the entire sample, which consists of 104.0 g in two pieces (85.6 and 18.4 g), additional small fragments (0.8 g), a polished thin section, and a potted butt.

Data from:
  Table 0
  Line 0:
Place of purchase:Tucson
Date:P 2004 Feb
Mass (g):111
Shock stage:S5
Weathering grade:W1
Classifier:K. Farley and A. Ruzicka, Cascadia
Type spec mass (g):104.8
Type spec location:Cascadia
Main mass:Cascadia
Comments:Lab number CML0157; submitted by A. Ruzicka
   and collections
Cascadia: Cascadia Meteorite Laboratory, Portland State University, Department of Geology, Room 17 Cramer Hall, 1721 SW Broadway, Portland, OR 97201, United States; Website (institutional address; updated 28 Oct 2011)
Thompson: Edwin Thompson, 5150 Dawn St., Lake Oswego, OR 97035, United States (private address)
References: Published in Meteoritical Bulletin, no. 105, MAPS 52, 2411, September 2017. http://onlinelibrary.wiley.com/doi/10.1111/maps.12944/full
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     This is 1 of 9829 approved meteorites from (Northwest Africa) (plus 1851 unapproved names)

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