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El Médano 200
Basic information Name: El Médano 200
     This is an OFFICIAL meteorite name.
Abbreviation: EM 200
Observed fall: No
Year found: 2011
Country: Chile
Mass:help 2.4 g
Meteoritical Bulletin:  MB 102  (2014)  C3
Recommended:  C3    [explanation]

This is 1 of 3 approved meteorites classified as C3.   [show all]
Search for other: Carbonaceous chondrites, Carbonaceous chondrites (type 3), and Ungrouped chondrites
Comments: Approved 12 Sep 2013
Writeup from MB 102:

El Médano 200        ~24°51’S, ~70°32’W

Antofagasta, Chile

Found: 2011 Oct 29

Classification: C3

History: A single stone was found in the Atacama desert by Pierre Rochette in October 2011.

Physical characteristics: A single 2.4 g stone with fusion crust. The interior is uniformly dark and porous.

Petrography: (J. Gattacceca, CEREGE) The meteorite consists of small chondrules (mostly type I, often with a fine-grained dark rim), chondrule fragments, mineral fragments (up to one mm) in a fine-grained matrix. Modal abundances: matrix 55%, chondrules and mineral fragments 45%. Chondrule mean size is 130±80 μm (N=41). Some chondrules show Fe diffusion rims in the olivine (~2 μm thick). Presence of dusty olivine. Abundant assemblages of magnetite and sulfides (troilite) up to 100 μm. Rare metal. Based on magnetic measurements, magnetite content is estimated to ~19 wt.% under the form of fine grains in the matrix. Powder XRD pattern lacks phyllosilicate reflections. Raman spectra of the matrix (L. Bonal, IPAG) suggest minimal thermal metamorphism. IR spectra of the matrix (L. Bonal, IPAG) suggest some aqueous alteration and the presence of carbonates.

Geochemistry: Olivine Fa0.3-69.5 (mean 22.7±23.6, PMD Fa = 94%, N=39). Cr2O3 in ferroan olivine is 0.36±0.24 wt.% (N=30). Orthopyroxene Fs1.6±0.5Wo0.7±0.4 (N=7). Ca-rich pyroxene Fs1.5-17.4Wo42.3-28.1 (N=3). Three metal analyses give Fe46.5±3.5Ni53.5±2.3 indicating Ni-rich taenite or tetrataenite. Oxygen isotopic compositions: (J. Gattacceca and C. Sonzogni, CEREGE) analysis of a 1.5 mg acid-washed sample by laser fluorination gave δ17O = -5.15, δ18O = -1.74, Δ17O = -4.25 (all per mil). Mag susceptibility log χ =5.08 (χ in 10-9 m3/kg).

Classification: C3 with affinities to CO3.

Specimens: One gram and a polished section at CEREGE. Main mass with CEREGE.

Data from:
  Table 0
  Line 0:
Origin or pseudonym:deflation surface
Date:2011 Oct 29
Mass (g):2.4
Weathering grade:low
Fayalite (mol%):22.7±23.6 (N=39)
Ferrosilite (mol%):1.6±0.5 (N=7)
Wollastonite (mol%):0.7±0.4 (N=7)
Magnetic suscept.:5.08
Classifier:J. Gattacceca, B. Devouard (CEREGE), M. Gounelle (MNHNP)
Type spec mass (g):1
Type spec location:CEREGE
Main mass:CEREGE
Finder:Pierre Rochette
Comments:Submitted by J. Gattacceca
Plots: O isotopes:  
   and collections
CEREGE: CEREGE BP 80 Avenue Philibert, Europole de l'Arbois 13545 Aix-en-Provence Cedex 4 France, France (institutional address; updated 9 Mar 2016)
MNHNP: Museum National d'Histoire Naturelle, 61 Rue Buffon, LMCM-CP52, 75005 Paris, France, France; Website (institutional address; updated 8 Nov 2012)
IPAG: Institut de Planétologie et d’Astrophysique de Grenoble 414, Rue de la Piscine Domaine Universitaire 38400 St-Martin d’Hères , France (institutional address; updated 1 Aug 2013)
References: Published in Meteoritical Bulletin, no. 102, MAPS 50, 1662, September 2015
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     Recommended::   (24° 51'S, 70° 32'W)

     This is 1 of 925 approved meteorites from Antofagasta, Chile (plus 1 impact crater)
     This is 1 of 950 approved meteorites from Chile (plus 9 unapproved names) (plus 1 impact crater)
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