NWA 4642 (1,240 g)
Northwest Africa 4642
History: The meteorite was found by an anonymous finder in northwest Africa and bought by the main mass holder in Erfoud, Morocco.
Physical characteristics: One fragment of 483.2 g partly covered with fusion crust was found.
Petrography: (A. Greshake, MNB) The meteorite predominantly consists of subhedral enstatite grains. Minor phases include feldspar, Fe-Cr-sulfides, and rare Fe,Ni-metal; no chondrules were found.
Geochemistry: Pyroxene, Fs0–1.2. Oxygen Isotopes (I. A. Franchi and R. C. Greenwood, OU): δ17O = 2.975‰, δ18O = 5.614‰, Δ17O = 0.056‰.
Classification: Enstatite achondrite; low degree of shock, moderate degree of weathering.
Type specimens: A total of 22.6 g and one polished thin section are on deposit at MNB. HSSH holds the main mass.
Mass (g): 483.2
Class: Enstatite achondriteFerrosilite (mol%):0-1.2
Classifier: A. Greshake, MNB
Type spec mass (g): 22.6
Type spec location: MNB
Main mass: HSSH
Comments: δ17O = 2.975‰, δ18O = 5.614‰, Δ17O = 0.056‰.