Compositional heterogeneity within a dumbbell-shaped Apollo 15 green glass: Evidence for simultaneous eruption of different magmas

The Apollo 15 green glasses that occur most prominently in 15425, 15426, and 15427 consist of compositionally distinct groups. The six groups that have thus far been defined are thought to represent different batches of magma that were erupted as fire-fountains, probably at different times in lunar history; although isotopic analyses of representative glasses within some of these groups have not yet found any differences in age at the +/- 100 Ma precision. While the petrogenesis of these picritic magmas has been contentious, the discovery of a compositionally heterogeneous, dumbbell-shaped green glass raises additional questions and problems about their origin.