Bulk compositions, petrology and mineralogy of >0.5 mm Luna 16 aluminous mare basalt particles are described. The data rule out any close genetic relationships between Luna 16 and other major types of lunar mare basalts. Compared to high-Ti mare basalts, the Luna 16 basalts contain lower TiO2 (5.1 wt %) and Ta (~0.8 ppm) and higher Al2O3 (13.3 wt %) and REE (~30--70X chrondrites) abundances, suggesting that the Luna 16 source rocks crystallized later than (i.e. stratigraphically above) the ilmenite-bearing high-Ti basalt cumulate source rocks. The REE pattern for the Luna 16 basalts requires that the source material from which they were derived crystallized from a light REE enriched magma.