Basaltic vitrophyre 15597 - An undifferentiated melt sample.

The vitrophyric nature and textural appearance of the Apollo 15 sample 15597, and the unusual compositions of its pigeonite centers and chromites, as well as the extreme chemical zonation of its pyroxenes, give strong evidence that this rock arrived on the lunar surface in an entirely liquid state. It may represent a 'primitive melt,' or at least a precursor from which mare lavas were derived.