Meteoritical Bulletin, No. 108
Northwest Africa 6831
Mass: 20 g
History: The meteorite was purchased in 2009 from a local
meteorite dealer in Erfoud, Morocco.
Physical characteristics: Dark
greyish individual without fusion crust.
Greshake, MNB) The meteorite is a
relatively fine-grained fragmental breccia composed of up to 1 mm sized
lithic and mineral clasts consolidated by a vesicular vitreous groundmass.
Lithic clasts include basaltic and melt clasts; mineral clasts are
dominantly calcic plagioclase, ferroan olivine, low-Ca pyroxene, pigeonite,
and Ca-pyroxene. Minor phases include chromite, ilmenite, fayalite, and
Geochemistry: olivine: Fa40.7±5.5
(Fa31.7-50.4, n=25, FeO/MnO=82-102); low-Ca pyroxene: Fs23.7±0.2Wo3.5±0.3
(Fs23.5-24.0Wo3.2-4.0, n=5, FeO/MnO=55-66); pigeonite:
n=9, FeO/MnO=47-61); Ca-pyroxene: Fs60.7±3.6Wo24.5±2.0
(Fs54.6-67.3Wo20.1-26.9, n=9, FeO/MnO=66-75); calcic
plagioclase: An92.6±1.3 (An90.1-93.8, n=20).
Specimens: Stefan Ralew