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Northwest Africa 6999
Basic information Name: Northwest Africa 6999
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 6999
Observed fall: No
Year found: 2000
Country: (Northwest Africa)
Mass:help 7.47 kg
Classification
  history:
Meteoritical Bulletin:  MB 101  (2012)  L/LL4
Recommended:  L/LL4    [explanation]

This is 1 of 20 approved meteorites classified as L/LL4.   [show all]
Search for other: L chondrites, L/LL chondrites, L/LL chondrites (type 4-7), LL chondrites, Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 7 Jul 2012
Writeuphelp
Writeup from MB 101:

Northwest Africa 6999 (NWA 6999)

(Northwest Africa)

Purchased: Aug 2000

Classification: Ordinary chondrite (L/LL4)

History: A 7.465 kg meteorite was purchased by David Gregory in August 2000 as part of a collection of NWA 869 strewn field material.

Physical characteristics: The meteorite is composed of heterogeneous ordinary chondrite material with no obvious brecciation. The fusion crust is generally rust-brown and variable in its degree of terrestrial weathering and thickness. Several fractures are visible through the fusion crust and are observed as shock veins. The interior is beige gray, with iron staining proximal to the fusion crust and shock veins/fractures.

Petrography: (K. van Drongelen, ROM) Meteorite composed of chondrules (70%), troilite (5%), Ni-Fe metal and oxides (5%) and matrix material. Chondrules show a varied degree of definition from clearly to poorly defined with no obvious preferred spatial distribution and consist of barred olivine, porphyrytic olivine, pyroxene, and olivine-pyroxene; radial pyroxene; and granular chondrules. Chondrules range from 0.5 to 6.5 mm in diameter, with an average of 1.5-2.0 mm, and are generally sub-circular in shape. Troilite and Ni-Fe metal consist of individual grains, grains within chondrules, and shock veins. The matrix (grain size <50-500 μm) ranges from easy to difficult to distinguish from chondrules and chondrule fragments. The meteorite contains shock veins and melt pockets, which are also found as a concentration in the center of the cut face (a macroscopically visible darkened area). Olivine exhibit irregular fractures, undulose extinction, and fine planar fractures.

Geochemistry: (Katrina van Drongelen, ROM) Olivine Fa=25.9±2.2 (n=66); low-Ca pyroxene (n=31) Fs23En75Wo2; high-Ca pyroxene (n=15) Fs16En52Wo32.

Classification: (Katrina van Drongelen, ROM) Ordinary Chondrite (L/LL4), S3, W2.

Specimens: Five thin sections and 7.387 kg are on deposit at the ROM.

Data from:
  MB101
  Table 0
  Line 0:
Place of purchase:Tucson
Date:P Aug 2000
Mass (g):7465
Pieces:18
Class:L/LL4
Shock stage:S3
Weathering grade:W2
Fayalite (mol%):25.9±2.2 (n=66)
Ferrosilite (mol%):23.1±4.1 (n=31); 15.8±8.0 (n=15)
Wollastonite (mol%):1.9±0.6 (n=31); 32.4±14.4 (n=15)
Classifier:K. van Drongelen, ROM
Type spec mass (g):7387
Type spec location:ROM
Main mass:ROM
Comments:Submitted by Kim Tait
Institutions
   and collections
ROM: Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada (institutional address; updated 18 Oct 2011)
Gregory: David Gregory, 230 First Avenue, Suite 108, St. Thomas, Ontario N5R 4P5, Canada (private address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 101, MAPS 50, 1661, September 2015
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 6781 approved meteorites from (Northwest Africa) (plus 2047 unapproved names)

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