NWA 12757 (32,131 g)
Northwest Africa 12757 (NWA 12757)
Classification: HED achondrite (Eucrite)
History: The meteorite was purchased from a local meteorite dealer in Morocco.
Physical characteristics: Grayish rock with some fusion crust.
Petrography: Monomict breccia composed of up to 6 mm sized mineral fragments which are predominantly exsolved pyroxene and calcic plagioclase. Pyroxene is either augite with low-Ca exsolution lamellae or vice versa. Plagioclase shows signs of recrystallization. Minor phases include Fe-rich olivine, silica, FeS, chromite, and barite; no metallic Fe has been found. Contains shock melt.
Geochemistry: low-Ca pyroxene: Fs65.7±2.4Wo2.9±0.8 (Fs60.3-67.6Wo2.2-4.9, n=12, FeO/MnO=25-34); Ca-pyroxene: Fs29.3±2.5Wo42.5±0.7 (Fs26.4-32.6Wo40.6-43.0, n=11, FeO/MnO=29-35); olivine: Fa81.6±3.2 (Fa75.6-84.8, n=19, FeO/MnO=37±7); calcic plagioclase: An90.7±1.1 (An88.2-92.0, n=12)
Place of purchase: Morocco
Date: P 2015
Mass (g): 298
Shock stage: high
Weathering grade: low
Ferrosilite (mol%): 65.7; 29.3
Wollastonite (mol%): 2.9; 42.5
Classifier: A. Greshake, MNB
Type spec mass (g): 20.3
Type spec location: MNB
Main mass: Philippe Schmitt-Kopplin
Comments: Submitted by Ansgar Greshake