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Northwest Africa 16595
Basic information Name: Northwest Africa 16595
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 16595
Observed fall: No
Year found: 2021
Country: (Northwest Africa)
Mass:help 99.2 g
Classification
  history:
Recommended:  Eucrite-mmict    [explanation]

This is 1 of 288 approved meteorites classified as Eucrite-mmict.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 4 Apr 2024
Writeuphelp
Writeup from MB 113:

Northwest Africa 16595 (NWA 16595)

(Northwest Africa)

Purchased: 2021

Classification: HED achondrite (Eucrite, monomict)

History: Purchased by Edwin Thompson in early 2021 from a meteorite broker in Mauritania, who said it was found in the Adrar region of Mauritania. Acquired in May 2021 by Cascadia as part of a trade.

Physical characteristics: Physical Characteristics: The single stone was covered with a dark fusion crust with shrinkage crack. Two areas where the fusion crust was missing showed a light gray interior. The cut face shows dark clasts containing white rectangular plagioclase grains set in a light- to medium-gray clastic matrix.

Petrography: (M. Hutson, A. Ruzicka, Cascadia): The sample is composed of clasts with sub-ophitic texture set in a clastic matrix. In addition to plagioclase feldspar and zoned pyroxene, the sub-ophitic clasts contain abundant silica and ilmenite, with small phosphate and sulfide grains. No chromite or metal was observed in the section. Ferrous olivine is present in veins and small single grains, as well as in symplectitic patches composed of ferrous olivine, low-Ca pyroxene, augite, ilmenite, and silica. The clastic matrix is composed of fragments of material found in the sub-ophitic clasts.

Geochemistry: Pyroxene analyses plot in four areas on a pyroxene quadrilateral: there is a concentration of analyses with Wo<5 and Fs54-65 (low-Ca pyroxene); a broad horizontal swath of analyses with Wo5-10 and Fs32-62 (pigeonite); a concentration of augite analyses with Wo>40 and Fs29-43; and 15 analyses for ferroan grains that lie along tie lines between low- and high-Ca pyroxenes. Individual pyroxene grains show normal zoning, with sharp boundaries between Mg-rich cores and more ferrous rims; in one grain the core is Fs32.2Wo5.5 and the rim is Fs61.5Wo6.1. Average pyroxene analyses: Low-Ca pyroxene Fs62.4±3.9Wo2.3±1.2, range Fs54.2-65.1Wo1.5-4.9, Fe/Mn (molar) = 28.7±0.7, N=14; pigeonite Fs47.3±10.4Wo6.9±1.5, range Fs32.2-61.7Wo5.1-9.2, Fe/Mn = 29.3±1.8, N=24; augite Fs29.2±0.4Wo43.4±0.6, range Fs28.7-29.5Wo43.0-44.3, N=4. Ferrous olivine found in veins and symplectitic intergrowths: Fa83.2±3.8, Fe/Mn = 38.0±0.9, N = 21. Plagioclase feldspar: Ab13.2±2.1An85.8±2.4Or0.9±0.4. N = 17.

Classification: HED achondrite (Eucrite, monomict) based on the mineral chemistry and texture of clasts and matrix. The meteorite overall has unequilibrated pyroxene grains.

Specimens: Cascadia holds 94.7 g in five pieces, as well as a polished thin section.

Data from:
  MB113
  Table 0
  Line 0:
Place of purchase:e-mail
Date:P 2021
Mass (g):99.2
Pieces:1
Class:Eucrite-mmict
Shock stage:M-S2
Weathering grade:low
Fayalite (mol%):83.2±3.8 (N=21)
Ferrosilite (mol%):47.3±10.4 (N=24)
Wollastonite (mol%):6.9±1.5 (N=24)
Classifier:M. Hutson, A. Morrelli, and A. Ruzicka, Cascadia
Type spec mass (g):94.7
Type spec location:Cascadia
Main mass:Cascadia
Comments:Lab number CML 1410; 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:
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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