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NWA 2650 Northwest Africa A 2224 g complete stone that measures 189 mm x 112 mm x 82 mm at the widest points, with fresh crust was purchased in Erfoud, Morocco, Description and classification (T. Bunch and J. Wittke, NAU): cataclastic, cumulate eucrite; coarse-grained (plagioclase up to 7 mm and pyroxenes to 5 mm); zones of intense crushing with minor recrystallization; discontinuous melt veins and pockets. Plastic deformation and offset faulting in plagioclase; minor amounts of maskelynite; undulatory extinction, shock twinning, and reduced birefringence in pyroxenes; shock level, S3-5. Extensive development of albite, Carlsbad, and complex igneous twinning in plagioclase. Exsolution lamellae of subcalcic augite (Fs52.5Wo15.9) in inverted ferrohypersthene (Fs61.1Wo3.8) and separate grains of augite (Fs25.1Wo45.7), FeO/MnO of all pyroxenes between 32.2 and 34.8. Plagioclase, An90.8 and minor amounts of ilmenite and chromite, cr# = 68-75. Low weathering grade. Specimens: type specimen, 23.1 g, NAU; main mass, D. Schultz. This is a very rare and beautiful Cumulate Eucrite! I sent this stone off to Germany for cutting on a wire saw, and the slices are great! Large complete slices, most measuring 130 mm long by 90 mm wide, by 4mm thick. These slices are fit for any museum display in the world. As you can see, there are both melted and crystallized areas in this meteorite. |
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