Bulk compositionspetrology 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 basaltsthe Luna 16 basalts contain lower TiO2 (5.1 wt %) and Ta (∼ 0.8 ppm) and higher Al2O3 (13.3 wt %) and REE (∼ 30‐70X chondrites) abundancessuggesting 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.

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We discuss the composition and chronology of clasts representing three minor lithologies in consortium breccia 67915. The lithologies studied are: sodic ferrogabbro, pristine troctolitic anorthosite (67915,26), and granulitic troctolitic anorthosite (67915,67). These lithologies were presumed to represent samples of the ancient lunar crust. The pristine troctolitic anorthosite, a typical member of the pristine anorthosite suite, contains little or no trapped liquid consistent with its two‐phase mineralogy. The plagioclase separates have 39Ar‐40Ar plateau ages of 4.10±0.06 b.y., and a final rise in the age pattern may represent a ‘memory’ of the earlier evolution. The granulitic troctolitic anorthosite, which has 13 times larger REE abundances, displays a continuous rise of the 40Ar/39Ar ratio. The last 25% of the 39Ar release data establish a minimum age of >3.5 b.y., but the 244Pu/Nd chronology suggests an age of ∼4.3 b.y. The sodic ferrogabbro samples, which appear to be members of the Mg‐gabbronorite group of pristine rocks, show large Ar losses but indicate plateaus in the low‐temperature data, suggesting a metamorphic event more recently than 260 m.y. ago, a time that is consistent with the North Ray impact event 50 m.y. ago.