NWA 15818 ( 4,550 g )
Northwest Africa 15818 (NWA 15818)
Classification: Carbonaceous chondrite (CO3)
History: The meteorite was purchased from a meteorite dealer in Mauritania.
Physical characteristics: Two large rocks weighing 5005 and 645 g, plus many small fargments, some partly covered with fusion crust.
Petrography: The meteorite shows a brownish interior and is predominantly composed of abundant small chondrules, CAIs, and mineral fragments set into a fine-grained matrix. Chondrules have a mean diameter of about 150 µm. Opaque phases are metal and troilite partly altered to iron oxides and hydroxides.
Geochemistry: Oxygen isotopic composition (J. Gattacceca, C. Sonzogni, D. Au Yang, CEREGE) from analysis of one acid-washed 2.5 mg aliquot of a powdered 104 mg bulk sample is δ17O=-4.398‰, δ18O=-1.324‰ , Δ17O=-3.710‰ (slope 0.52, analytical uncertainties 0.08‰, 0.12‰, 0.03‰, respectively)
|Place of purchase:||Mauritania|
|Fayalite (mol%):||19.7±21.0 (0.6-65.1, n=18)|
|Ferrosilite (mol%):||2.7±1.6 (1.0-5.6, n=12)|
|Wollastonite (mol%):||1.2±0.3 (0.9-1.7, n=12)|
|Classifier:||A. Greshake, MNB|
|Type spec mass (g):||29.2|
|Type spec location:||MNB|
|Main mass:||Boulaouane Taleb Ahmed|
|Comments:||Submitted by Ansgar Greshake|