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Northwest Africa 11860
Basic information Name: Northwest Africa 11860
     This is an OFFICIAL meteorite name.
Abbreviation: NWA 11860
Observed fall: No
Year found: 2017
Country: (Northwest Africa)
Mass:help 520 g
Classification
  history:
Recommended:  R3-5    [explanation]

This is 1 of 14 approved meteorites classified as R3-5.   [show all]
Search for other: Rumuruti chondrites, Rumuruti chondrites (type 3)
Comments: Approved 24 Jul 2018
Writeuphelp
Writeup from MB 107:

Northwest Africa 11860 (NWA 11860)

(Northwest Africa)

Purchased: 2017

Classification: Rumuruti chondrite (R3-5)

History: A single stone weighing 520 g was found in Morocco prior to 2017. J. Donald Cline and John Sinclair acquired the sample from a meteorite dealer at the Tucson Gem and Mineral Show in February of 2017.

Physical characteristics: Sample is black in color, lacks fusion crust, has a rounded flattened shape with shallow broad regmaglypts. A small cut face shows brecciated texture composed of clasts set within abundant small chondrules, which, are visible through the patina. Sample is non-magnetic and only sulfides appear to reflect light on the surface of the cut face.

Petrography: Description and Classification (A. Love, App) Sample is a breccia composed of up to 3 cm irregularly shaped, light-orangish to brown-black unequilibrated and equilibrated clasts set within a recrystallized host containing chondrules (avg. dia. 432 μm), fragments and abundant Ni-bearing sulfides and pentlandite. Host contains 40 vol% well-defined, unequilibrated chondrules set within a recrystallized matrix. Unequilibrated clasts contain chemically-zoned, unequilibrated chondrules set within a fine-grained, opaque matrix. Equilibrated clasts contain olivine, low-Ca pyroxene within a recrystallized matrix containing isolated intergrowths of plagioclase with average size 30 μm (Berlin and Stoeffler, 2004).

Geochemistry: (A. Love, App) Host: Olivine Fa25.0±14.7 (Fa2.1-48.5), Cr2O3 in ferroan olivine=0.1±0.1, Fe/Mn=74.5 n=22, Low Ca Pyroxene: Fs13.8±9.2Wo1.1±1.0 (Fs2.1-28.1Wo0.3-3.1), N=9. Clast: Olivine Fa 41.8±0.3, Fe/Mn=94.5±2.2, n=5, low Ca Pyroxene: Fs36.0±0.2Wo2.2±0.3, N=3.

Classification: Rumuruti chondrite (R3-5, S2, wi-2). Based on Fa and Fe/Mn compositions of olivines, chondrule diameter and texture this sample is a Rumuruti chondrite breccia. Based on the coefficient of variation of olivine within unequilibrated clast, the petrologic subtype is estimated at 3.4 (Bischoff, 2000). Based on presence of low-Ca pyroxene and isolated plagioclase intergrowths within equilibrated clasts, these represent type 5 material.

Specimens: PARI holds the main mass. One endcut weighing 20.02 g and a polished thin section are on deposit at App.

Bibliography:
  • Bischoff, A. (2000) Mineralogical characterization of primitive, type-3 lithologies in Rumuruti chondrites. Meteorit. Planet. Sci. 35 699-706 (link)
Data from:
  MB107
  Table 0
  Line 0:
Place of purchase:Tucson Gem and Mineral Show
Date:P 2017
Mass (g):520
Pieces:1
Class:R3-5
Shock stage:S2
Weathering grade:W2
Fayalite (mol%):25.0±14.7; 41.8±0.3
Ferrosilite (mol%):13.8±9.2; 36.0±0.2
Wollastonite (mol%):1.1±1.0; 2.2±0.3
Classifier:A. Love, App
Type spec mass (g):20.0
Type spec location:App
Main mass:PARI
Finder:Unknown
Comments:Submitted by Anthony Love
Institutions
   and collections
App: Department of Geology, 572 Rivers St., Appalachian State University, Boone, NC 28608, United States (institutional address; updated 7 Mar 2013)
PARI: Pisgah Astronomical Research Institute 1 Pari Dr Rosman, NC 28772, United States (institutional address; updated 13 Sep 2016)
Catalogs:
References: Published in Meteoritical Bulletin, no. 107, in preparation (2018)
Find references in NASA ADS:
Find references in Google Scholar:
Geography: 
Coordinates:Unknown.

Statistics:
     This is 1 of 7005 approved meteorites from (Northwest Africa) (plus 2002 unapproved names)

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