A single stone weighing 3,250 g was purchased in Morocco. Petrographic analysis was performed at Johnson Space Center by M. Zolensky, and this meteorite was classified as a very fresh (W1) LL5 chondrite, which has been very weakly shocked to stage S2. Current studies suggest that type-5 ordinary chondrites of shock stage S2 were initially shocked to a greater degree, at least stage S3, which was followed by a period of annealing to stage S1, and finally, very weakly shocked again to stage S2 (Rubin, 2003). The type specimen of NWA 1584 is curated at the National Museum of Natural History, Smithsonian Institution.
Northwest Africa 1584 is a typical member of the low Fe, low metal chondrite group, having a high Fa (28.3) and Fs (25.2) content. This reflects the incorporation of much of the available metal into the silicates. This meteorite is comprised of large chondrules, minor FeNi-metal, and sulfide, along with mineral and lithic components, which are embedded in a very light-colored matrix. Light brown limonitic staining occurs around some metal particles. The photo above shows a 10.2 g partial slice.
