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Northwest Africa 13235
Basic information Name: Northwest Africa 13235
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 13235
Observed fall: No
Year found: 2019
Country: (Northwest Africa)
Mass:help 1344 g
Classification
  history:
Recommended:  Howardite    [explanation]

This is 1 of 384 approved meteorites classified as Howardite.   [show all]
Search for other: Achondrites, HED achondrites, and Howardites
Comments: Approved 5 Apr 2020
Writeuphelp
Writeup from MB 109:

Northwest Africa 13235 (NWA 13235)

(Northwest Africa)

Purchased: 2019

Classification: HED achondrite (Howardite)

History: The meteorite was found by Muhhamad Imam in Mali and sebsequently purchased by Marcin Cimała.

Physical characteristics: Light to dark grayish rock with some larger cavities and few patches of fusion crust.

Petrography: The meteorite is an achondritic melt breccia consisting of large black-white speckled to completely black melt regions showing pronounced flow structures and whitish less intensely or entirely unmelted clasts. Melt regions are composed of exsolved pyroxene, recrystallized pyroxene displaying mottled compositional zoning, and calcic plagioclase fragments set into a recrystallized matrix of pyroxene and often fibrous feldspar. Vesicles are abundant in the matrix and the mineral fragments frequently show resorbtion features at their contact to the melt. Unmelted regions show an overall eucritic mineral assemblage with exsolved pyroxene and plagioclase fragments set into a clastic matrix. Minor phases are silica, chromite, FeS, and rare metallic iron. The meteorite contains large up to 4 mm sized diogenetic low-Ca pyroxenes some of which have olivine, augite, and/or feldspar inclusions. Due to the heterogeneity of the material it is not possible to determine the percentage of diogenetic material precisely, i.e., more or less than 10 vol.%. The unmelted precursor was, thus, either a polymict eucrite or a howardite.

Geochemistry: diogenetic pyroxene: Fs34.3±0.2Wo2.0±0.4 (Fs33.9-34.7Wo1.7-3.2, n=12, FeO/MnO=27-30); olivine: Fs49.0±0.5 (Fs48.4-49.7, n=11, FeO/MnO=46±1); eucritic low-Ca pyroxene: Fs59.8±0.3Wo1.8±0.1 (Fs59.2-60.2Wo1.7-1.9, n=11, FeO/MnO=28-32); eucritic Ca-pyroxene: Fs24.5±1.7Wo44.0±0.4 (Fs21.5-25.9Wo43.1-44.7, n=14, FeO/MnO=26-32); calcic plagioclase: An92.7±0.6 (An91.6-93.6, n=12)

Classification: Howardite-melt breccia due to presence of eucritic and diogenetic material embedded in a melt rock matrix.

Data from:
  MB109
  Table 0
  Line 0:
Place of purchase:Mali
Date:P 2019
Mass (g):1344
Pieces:1
Class:Howardite
Shock stage:high
Weathering grade:low
Fayalite (mol%):49.0
Ferrosilite (mol%):34.3; 59.8; 24.5
Wollastonite (mol%):2.0; 1.8; 44.0
Classifier:A. Greshake, MNB
Type spec mass (g):25.6
Type spec location:MNB
Main mass:Marcin Cimala
Finder:Muhhamad Imam
Comments:Submitted by Ansgar Greshake
Institutions
   and collections
MNB: Museum für Naturkunde, Invalidenstraße 43, D-10115 Berlin, Germany (institutional address; updated 24 Dec 2011)
Catalogs:
References: Published in Meteoritical Bulletin, no. 109, in preparation (2020)
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)
Marcin Cimala      
Public domain photographs:
Ansgar Greshake         
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 7385 approved meteorites from (Northwest Africa) (plus 1955 unapproved names)

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