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Northwest Africa 12688
Basic information Name: Northwest Africa 12688
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 12688
Observed fall: No
Year found: 2017
Country: (Northwest Africa)
Mass:help 140 g
Classification
  history:
Recommended:  Ureilite    [explanation]

This is 1 of 531 approved meteorites classified as Ureilite.   [show all]
Search for other: Achondrites, Ureilites
Comments: Approved 13 Jun 2020
Writeuphelp
Writeup from MB 109:

Northwest Africa 12688 (NWA 12688)

(Northwest Africa)

Purchased: 20 Apr 2017

Classification: Ureilite

History: The meteorite was purchased from Mr. Aziz Habibi in Agadir (Morocco) in April 20, 2017.

Physical characteristics: Single stone of 140 g total weight has angular shape and dark brownish surface. Fusion crust is not preserved.

Petrography: (Lorenz C. A., Vernad) The rock has coarse grained (0.5-1 cm) metamorphic texture with triple junctions of mineral grains and composes of clino and orthopyroxene and olivine. Clinopyroxene contains rare large inclusions of olivine, orthopyroxene and glass. Accessory metal Fe and sulfide form thin linear veinlets along the silicate grains borders and are mostly replaced by Fe-hydroxides. Rare rounded inclusions of intergrown metal Fe, troilite and shreibersite occur within the silicate grains. Olivine has undulatory optical extinction, irregular and planar fractures. Some olivine grains are rich in fine-grained vermicular aggregates of troilite associated with the veinlets. Graphite was not found.

Geochemistry: Mineral compositions and geochemistry: (N. N. Kononkova, EMP, Vernad) Pyroxene: Fs10.6±0.2Wo4.7±0.3 (in wt%: Al2O3 = 1.23±0.19; Cr2O3 = 1.09±0.07; Fe/Mn = 12.0±1.6; N = 18); Ca-pyroxene Fs6.4±0.3Wo38.5±2.1 (in wt%: Al2O3 = 2.59±1.66; Cr2O3 = 1.29±0.17; TiO2 = 0.4 ± 0.2; Fe/Mn = 12.0±1.6; N = 7); Glass, in wt%: SiO2 = 60.0; Al2O3 = 23.5; Na2O = 4.81; CaO = 8.78; FeO = 2.41; MgO = 2.13; metal Fe (in wt%): Ni = 1.7; P = 1.2; Si < 0.04; Ni/Co=7.7; troilite Cr = 2.0 wt%. Mineral norms from bulk analysis (T. G. Kuzmina, XRF, Vernad), in wt% Ol 54.2; Hyp 23.3; Di 18.9; Fsp 3.4; Oxygen isotopes (I. A. Franchi, OU, laser fluorination): δ17O = 3.13 δ18O = 7.78 Δ17O = -0.916; δ17O = 3.095 δ18O = 7.791 Δ17O = -0.956.

Classification: Based on a texture, mineral chemistry and oxygen isotopic composition the meteorite is classified as ureilite.

Specimens: Cutted piece and three sub-samples of 27.7 g in total, and thin polished section are on deposit in Vernad.

Data from:
  MB109
  Table 0
  Line 0:
Place of purchase:Agadir, Morocco
Date:P 20 Apr 2017
Mass (g):140
Pieces:1
Class:Ureilite
Fayalite (mol%):11.4±1.5 (N=40)
Ferrosilite (mol%):10.6±0.2 (N=18)
Wollastonite (mol%):4.7±0.3 (N=18)
Classifier:Lorenz C. A., Vernad
Type spec mass (g):27.7
Type spec location:Vernad.
Main mass:DMUH
Finder:anonymous
Comments:Analyst Kononkova N. N. (Vernad); submitted by Lorenz C.A., Vernad
Plots: O isotopes:  
Institutions
   and collections
OU: Planetary and Space Sciences Department of Physical Sciences The Open University Walton Hall Milton Keynes MK7 6AA United Kingdom, United Kingdom (institutional address; updated 8 Dec 2011)
Vernad: Vernadsky Institute of Geochemistry and Analytical Chemistry, Russia (institutional address; updated 21 Feb 2016)
DMUH: Dedovsk Museum of Universe History, Russia; Website (institutional address; updated 26 Sep 2011)
Catalogs:
References: Published in Meteoritical Bulletin, no. 109, in preparation (2020)
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 7354 approved meteorites from (Northwest Africa) (plus 1958 unapproved names)

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