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Northwest Africa 11761
Basic information Name: Northwest Africa 11761
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 11761
Observed fall: No
Year found: 2016
Country: (Northwest Africa)
Mass:help 2.26 kg
Meteoritical Bulletin:  MB 107  (2018)  Mesosiderite
Recommended:  Mesosiderite    [explanation]

This is 1 of 234 approved meteorites classified as Mesosiderite.   [show all]
Search for other: Mesosiderites, Metal-rich meteorites
Comments: Approved 11 May 2018
Writeup from MB 107:

Northwest Africa 11761 (NWA 11761)

(Northwest Africa)

Purchased: June 2016

Classification: Mesosiderite

History: The meteorite was purchased by an anonymous collector at St. Marie-aux-Mines, France, mineral show in June 2016 from an anonymous Moroccan dealer.

Physical characteristics: The stone of 2258 g total weight has irregular shape; the surface is reddish-brown; the fusion crust is not preserved.

Petrography: (C. A. Lorenz, Vernad) The meteorite has a brecciated texture; it is composed of lithic and mineral fragments (50 vol%) embedded into a troilite-metal-silicate melt matrix (13, 22, 15 vol% respectively). The mineral fragments are pyroxene, feldspar and silica; the rock fragments are fine-, medium- and coarse-grained pyroxene-feldspar rocks of equigranular, subophitic or gabbroic textures, fine-grained clastic and melt-matrix breccias and minor dunitic and peridothitic rocks. Coarse-grained pyroxenes contain the fine exsolution lamellae. The rock contains 11 vol% of fragments of >2 mm in size. The matrix has heterogeneous texture varying in troilite, metal and silicates composition. Matrix silicates forming intergrowths with troilite are fine-grained subhedral pyroxene, anhedral feldspar and glass. Metal-and sulfide-poor matrix surrounding large lithic fragments are fine-grained melt rock. Metal forms irregular and globular grains in the troilite matrix and is composed of kamacite with inclusions of taenite. Accessory minerals are silica and chromite.

Geochemistry: Mineral compositions and geochemistry: (Kononkova N. N., Vernad) Matrix pyroxene is En21.5-56.2Wo0.5-8.4 (Fe/Mn=16 - 30, at.), feldspar is An84.7-90.2Ab9.5-14.6; fragments pyroxene is En20.4-31.0Wo2.1-15.2 (Fe/Mn= 23 - 30, at.); feldspar is An94.5Ab5.5.

Classification: Mesosiderite of Type 4, anomalous; weathering is minimal. This mesosiderite is unusually troilite-rich and metal-poor.

Specimens: A piece and slices of 103 g total weight and thick section is on deposit in Vernad. Anonymous collector holds the main mass.

Data from:
  Table 0
  Line 0:
Place of purchase:St. Marie-aux-Mines (France)
Date:P June 2016
Mass (g):2258
Classifier:C. A. Lorenz, Vernad
Type spec mass (g):103
Type spec location:Vernad
Main mass:anonymous
Comments:Submitted by C. A. Lorenz (Vernad)
   and collections
Vernad: Vernadsky Institute of Geochemistry and Analytical Chemistry, Russia (institutional address; updated 21 Feb 2016)
References: Published in Meteoritical Bulletin, no. 107, MAPS 55, 460-462
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Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)
Cosimo Damiano Gorgoglione   
Lucian Cojocaru   

     This is 1 of 8777 approved meteorites from (Northwest Africa) (plus 1879 unapproved names)

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