Multiple stones and fragments totaling ~823 g were purchased in Morocco by an association of meteorite collectors known by the name of Trinity Meteorites. The exterior of this eucrite is covered with black fusion crust, and the interior is light tan in color with an ultra fine-grained texture, with mineral grains of pyroxene and plagioclase measuring tens of microns in size.
Northwest Africa 999 is a brecciated eucrite, possibly monomict, composed of very fine-grained basaltic material, which represent both the host and clasts in the meteorite. Widely scattered shock-melt veins of glass are present. The very fine-grained texture of this eucrite is consistent with rapid cooling from an extruded igneous melt. Although it exhibits the typical thermal metamorphic features characteristic of other equilibrated eucrites, it does not exhibit a high degree of textural equilibration (Warren and Choe, 2009). From a preliminary analysis performed by UCLA, NWA 999 was determined to be an extremely fine-grained eucrite that is slightly Fe-rich and REE-rich. The bulk composition of this eucrite plots with the Main Group–Nuevo Laredo trend. Black mineral grains (possibly chromite) are interspersed throughout the matrix, and a rare FeNi-metal grain is present in the specimen shown above. This eucrite experienced low- to moderate-shock and is cross-cut by thin, dark-gray, shock-melt veins. The specimen of NWA 999 shown above is a 2.44 g slice.