Northwest Africa 13789 (NWA 13789)
Classification: HED achondrite (Diogenite)
History: The meteorite was purchased from a dealer in Morocco.
Physical characteristics: Almost completely crusted fragment showing a grayish to orange interior.
Petrography: The meteorite is a monomict breccia predominantly composed of blocky up to 6 mm sized orthopyroxene grains and more fine-grained cataclastic regions. Minor phases include chromite, troilite, and unusually abundant metallic iron. No plagioclase has been found in the two sections studied. The meteorite is highly shocked and contains abundant shock melt veins and pockets.
Geochemistry: low-Ca pyroxene: Fs26.8±0.7Wo2.2±0.1 (Fs26.2-27.0Wo2.1-2.3, n=7, FeO/MnO=24-28; oxygen isotopes (K. Ziegler, UNM): 3 acid-washed fragments analyzed by laser fluorination gave: δ18O=3.306, 3.778, 3.046; δ17O=1.488, 1.713, 1.341; Δ17O= -0.257, -0.282, -0.267 (all per mil)