Northwest Africa 2977

Morocco or Algeria

Find: 2005 November

Achondrite (lunar, gabbro)

History: A single minimally weathered fusion-encrusted stone of 233 g was purchased from a Moroccan dealer in Tagounite, Morocco, by MFarmer in November 2005.

Petrography and Geochemistry: (J. Wittke and T. Bunch, NAU; A. Irving, UWS) The specimen consists of a single yellow-green, relatively coarse-grained rock traversed by thin, black glass-rich veins. It is an olivine-rich, two-pyroxene cumulate gabbro composed of olivine (Fa_31.7; FeO/ MnO = 96; 52 vol%), (Fs_26.6Wo_6.7; 23 vol%), augite (Fs_16.2Wo₂₉; 9 vol%), and plagioclase (An₅₆; 14 vol%) with minor amounts of Ba-K feldspar, chromite, ilmenite, and merrillite. Larger pigeonite grains commonly enclose equant olivine grains, which contain abundant melt inclusions (0.025–0.125 mm). Plagioclase is partially converted to maskelynite, and pyroxenes and olivine exhibit shock lamellae and undulatory extinction. Note: This specimen is identical in texture and mineral composition to the gabbro clasts in NWA 773 and NWA 2700 and thus appears to be paired with those breccia specimens.

Classification: Achondrite (lunar, gabbro); minimal weathering.

Specimens: A 20.1 g type specimen and one polished thin section are on deposit at NAU. A 0.5 g specimen is on deposit at WUSL. An anonymous owner holds the main mass.