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Northwest Africa 16532
Basic information Name: Northwest Africa 16532
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 16532
Observed fall: No
Year found: 2013
Country: (Northwest Africa)
Mass:help 48.2 g
Classification
  history:
Recommended:  Eucrite    [explanation]

This is 1 of 608 approved meteorites (plus 1 unapproved name) classified as Eucrite.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 5 Mar 2024
Writeuphelp
Writeup from MB 113:

Northwest Africa 16532 (NWA 16532)

(Northwest Africa)

Purchased: 2013 Oct

Classification: HED achondrite (Eucrite)

History: A 48.2 g end cut lacking the remainder of the stone was included in a lot of northwest African stones shipped to ET meteorites. Cascadia acquired this end cut on October 18, 2013.

Physical characteristics: Physical Characteristics: The exterior of the end cut is covered by light tan-orange weathering product; patches of dark-brown fusion crust are present. The cut face shows a coarse basaltic texture with white elongate feldspar grains and pale yellowish pyroxene grains. Fractures and light gray veins cut across the face.

Petrography: (M. Hutson, A. Ruzicka, Cascadia): In thin section, the sample is composed predominantly of exsolved high- and low-Ca pyroxene and calcic plagioclase feldspar grains. Plagioclase grains are clouded by inclusions and have undulose to mosaic extinction when viewed in cross-polarized light; some grains show offset twins. Textures vary from fine- to medium-grained granoblastic to coarse-grained sub-ophitic, with many fractures and faults cutting and offsetting sections of the thin section. BSE imaging shows numerous examples of pyroxene lamellae that are deformed or offset by microfaults, with apparent incipient melting adjacent to abundant thin, glassy veins. Of those veins that were analyzed, some are close to pyroxene normative, while others are feldspathic. Examples of schlieren were observed at the boundary between plagioclase glass and pyroxene grains. A silica polymorph is abundant throughout the section. Additional phases observed include ilmenite, an Al-Ti-bearing chromite, fluor-apatite, merrillite, and troilite. No olivine or metal grains were observed.

Geochemistry (M. Hutson, A. Morrelli, A. Ruzicka, Cascadia): Pyroxene and plagioclase feldspar compositions are relatively equilibrated. Low-Ca pyroxene: Fs64.4±1.0 Wo2.3±0.6 (range Fs62.6-66.1Wo1.6-3.6), molar Fe/Mn=30.5±1.0, N=21; augite (grains and lamellae): Fs28.8±0.9Wo43.1±0.9 (range Fs27.8-30.8Wo40.4-44.1), molar Fe/Mn=30.9±1.6, N=19; plagioclase feldspar: Ab10.7±0.8Or0.6±0.1An88.7±0.8 (range Ab9.3-12.1Or0.4-0.8An87.3-90.2), N=16.

Classification: HED achondrite (eucrite) based on mineralogy, texture, and pyroxene and feldspar compositions.

Specimens: Cascadia holds 42.9 g in one piece, as well as a polished thin section and material in an epoxy butt.

Data from:
  MB113
  Table 0
  Line 0:
Place of purchase:ET Meteorites/Portland, Oregon, USA
Date:P 2013 Oct
Mass (g):48.2
Pieces:1
Class:Eucrite
Shock stage:M-S3
Weathering grade:low
Ferrosilite (mol%):64.4±1.0 (N=21)
Wollastonite (mol%):2.3±0.6 (N=21)
Classifier:M. Hutson, A. Morrelli and A. Ruzicka, Cascadia
Type spec mass (g):42.9
Type spec location:Cascadia
Main mass:Cascadia
Comments:Lab number CML 0786; 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)
Catalogs:
References: Published in Meteoritical Bulletin, no. 113, in preparation (2024)
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Public domain photographs:
Melinda Hutson         
Geography: 
Coordinates:Unknown.

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

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