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Northwest Africa 16688
Basic information Name: Northwest Africa 16688
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 16688
Observed fall: No
Year found: 2006
Country: (Northwest Africa)
Mass:help 725 g
Classification
  history:
Recommended:  H5    [explanation]

This is 1 of 11988 approved meteorites (plus 23 unapproved names) classified as H5.   [show all]
Search for other: H chondrites, H chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 5 May 2024
Writeuphelp
Writeup from MB 113:

Northwest Africa 16688 (NWA 16688)

(Northwest Africa)

Purchased: 2006

Classification: Ordinary chondrite (H5)

History: Edwin Thompson purchased a single 725 g stone in Midelt, Morocco, in 2006 and gave Cascadia a 34.3 g piece for classification.

Physical characteristics: Physical Characteristics: Cascadia received a thin slice, which showed abundant metal and sulfide and numerous recognizable, but indistinct chondrules.

Petrography: (M. Hutson, A. Ruzicka, Cascadia): The commercially prepared thin section was poorly made; about 30% of the area of the thin section consists of pits which are dark in transmitted light. In reflected light and BSE imaging the sample appears to be only slightly weathered. There is minimum replacement of metal or sulfide by weathering product, and only a few very small oxide/hydroxide veins near some metal veins. No calcite veins are present. Chondrules are readily discerned, but have edges that grade into a heavily plucked matrix. Chondrule mesostases are crystalline and fine-grained, with most grains ~15 µm across. Very fine-grained chromite-plagioclase assemblages (chromite grains ~2.5 µm across) occur in some chondrule mesostases. Elsewhere, plagioclase feldspar grains are ~40 µm across. Numerous phosphate grains (~50 µm across), some confirmed as merrillite, are present.

Geochemistry: Olivine: Fa18.7±0.3, N=19; low-Ca pyroxene: Fs16.5±0.1Wo1.2±0.1, N=23; plagioclase feldspar Ab81.7±1.5Or4.9±0.9An13.4±1.8, N=6.

Classification: Ordinary chondrite (H5) based on mineral chemistry, texture, and feldspar size.

Specimens: Cascadia holds 32.1 g in one piece, as well as a polished thin section and material in an epoxy butt; Thompson holds the main mass.

Data from:
  MB113
  Table 0
  Line 0:
Place of purchase:Midelt, Morocco
Date:P 2006
Mass (g):725
Pieces:1
Class:H5
Weathering grade:W1
Fayalite (mol%):18.7±0.3 (N=19)
Ferrosilite (mol%):16.5±0.1 (N=23)
Wollastonite (mol%):1.2±0.1 (N=23)
Classifier:M. Hutson and A. Ruzicka, Cascadia
Type spec mass (g):34.3
Type spec location:Cascadia
Main mass:Thompson
Comments:Lab number CML 1696; submitted by Melinda Hutson
Institutions
   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)
Catalogs:
References: Published in Meteoritical Bulletin, no. 113, in preparation (2024)
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 9829 approved meteorites from (Northwest Africa) (plus 1851 unapproved names)

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