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Northwest Africa 13991
Basic information Name: Northwest Africa 13991
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13991
Observed fall: No
Year found: 2009
Country: (Northwest Africa)
Mass:help 122 g
Classification
  history:
Recommended:  Eucrite-pmict    [explanation]

This is 1 of 358 approved meteorites classified as Eucrite-pmict.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 29 May 2021
Writeuphelp
Writeup from MB 110:

Northwest Africa 13991 (NWA 13991)

(Northwest Africa)

Purchased: 2009 Jun

Classification: HED achondrite (Eucrite, polymict)

History: Purchased from a Moroccan mineral dealer at the mineral show in Sainte-Marie-aux-Mines, France

Petrography: (K. Metzler, IfP) Polymict achondritic breccia, consisting of eucritic lithic clasts (subophitic, gabbroic, granulitic) and mineral fragments (pyroxene, plagioclase) set in a fine-grained clastic matrix of related debris. Most pyroxenes exhibit augite exsolution lamellae. Several olivine fragments were found. Accessories are silica polymorph, chromite, troilite, and Ni-bearing metal.

Geochemistry: Mineral compositions and geochemistry: Granulitic eucrite clast: low-Ca pyroxene (host) Fs60.8±0.7Wo2.6±0.3 (Fs60.2-61.9Wo2.2-3.1); mean Fe/Mn (at.): 29.3; n=6. Ca-rich pyroxene (exsolution lamellae) Fs29.1±1.3Wo40.2±1.0 (Fs28.0-30.9Wo38.9-41.3); n=6. Plagioclase An87.8±1.0Or0.1±0.2 (An86.6-89.0Or0.0-0.5); n=8. Gabbroic eucrite clast: low-Ca pyroxene (host) Fs33.9±0.3Wo2.1±0.3 (Fs33.5-34.4Wo1.8-2.4); mean Fe/Mn (at.): 27.7; n=6. Ca-rich pyroxene (exsolution lamellae) Fs12.3±0.3Wo44.4±0.3 (Fs11.9-12.6Wo44.0-44.7); n=6. Plagioclase An92.3±0.6Or0.0±0.1 (An91.5-93.1Or0.0-0.1); n=8. Olivine fragments: Fa9.1±1.4 (Fa7.5-10.8); Fe/Mn (at.): 43.8; n=5.

Classification: Polymict eucrite

Data from:
  MB110
  Table 0
  Line 0:
Place of purchase:Sainte-Marie-aux-Mines, France
Date:P 2009 Jun
Mass (g):122
Pieces:1
Class:Eucrite-pmict
Shock stage:M-S2
Weathering grade:low
Fayalite (mol%):9.1±1.4
Ferrosilite (mol%):33.9-60.8; 12.3-29.1
Wollastonite (mol%):2.1-2.6; 44.4-40.2
Classifier:K. Metzler, IfP
Type spec mass (g):20
Type spec location:IfP
Main mass:anonymous
Comments:Submitted by K. Metzler (IfP)
Institutions
   and collections
IfP: Institut für Planetologie, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany (institutional address; updated 23 Jan 2012)
Catalogs:
References: Published in Meteoritical Bulletin, no. 110, in preparation (2021)
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Public domain photographs:
Knut Metzler            
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 7937 approved meteorites from (Northwest Africa) (plus 1960 unapproved names)

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